# 2001 Jetta 2.0 ECM electrical issue. Holy Crap HELP!



## barrishautomotive (Nov 11, 2011)

Sorry to cross post... I reallized after posting in the Mk IV section I should have posted here.

Ok so check this out. 2001 Jetta 2.0 GL manual trans, manual windows, AZG engine code. production date 10/00, late 2001 production model. I am by no means a newbie mechanic, nor am I new to electrical troubleshooting but this one’s insane. I’ll give you the full backstory first in order to not waste anyone’s time. I know that some of these details may seem irrelevant, but you never know so here goes…

A few weeks ago my little sister found herself in need of a car. After some looking, she and I found a super clean 2001 Jetta 2.0 stick shift with only 82,000 miles. I had a look over it and found no problems whatsoever aside from a battery in need of replacement. So she bought the car. The next day, we bought a brand new O’reilly battery and installed it in the car. The morning after that, the car decided not to start. It would crank over just fine, but it didn’t even think about trying to start. My sister called me. I went over to look at it. Sure enough, the car was cranking over but wouldn’t start. Everything else still worked fine, the lights, the stereo, the door locks, it just wouldn't start. I immediately noticed that the CEL and EPC lights were not illuminating with the key on. As I’m sure you all know, with the key on, but engine off, CEL and EPC lights should illuminate. I found this strange so I plugged my laptop into it and tried to scan it with Vag-Com. (I’m an Audi owner) No communication. Vag-Com was unaware that the car was even plugged in. I immediately figured the ECM must not be powering up. 

So I run down a checklist in my head, ignition switch, ECM fuses, ECM relay, ECM wiring, or the ECM itself. These are really the only things it could be in my mind. ECM fuses are good. Wiring all appears to be good. I was doubtful that it was the ECM. So I figured probably ignition switch. Unfortunately, at this point the car decided it was done acting up and suddenly the ECM power returned and the car started and ran fine and the ECM had not stored any fault codes.

The next morning I get the same call from my sister. I go to her house and this time I just cycle the key a couple of times and the ECM power returns and the car decides to run. Not being supremely confident in my abilities, I took the car to a VW specialist shop in town to check it out. He looked at it and said that it is almost certainly the ignition switch. So we had him replace the switch. No change. The car stalled out almost immediately after the switch was installed. Still no trouble codes. After seeing that the ignition switch was not at fault, the mechanic offered to put the old switch back in a refund our money, but we knew the switch is a common problem in these cars, so we decided to leave the new switch in. The mechanic advised us that it was probably an ECM issue and recommended we take the car to the dealership. So we did. This is where things get more fun. 

The dealership advises us that they’ve seen this car before. In February of this year the car had been brought in for a similar issue by its previous owner. The issue was diagnosed as a bad ECM. So the ECM was replaced. The car didn’t even make it a month from that time before the issue came back. The dealer then diagnosed it as a bad replacement ECM and replaced it again. They also advised me that if it turns out the ECM is bad, they will replace it for free under warranty. By this time the issue had become sporadically intermittent, so the dealer wasn’t able to consistently replicate the issue in order to troubleshoot. The dealer kept the car for several days, after which they tried to tell me it was a bad fuel pump. I called bullsh!t on that and asked them how a bad fuel pump could cause the CEL to not illuminate with the key on, engine off. I told them it sounds like a bad ECM and that they should replace the ECM. So they call me back later and tell me it’s a fuel pump relay. I told them I was doubtful, but to go ahead and replace it. 

I went to pick up the car, paid them their $180 and tried to drive away. I made it less than 2 blocks before the issue came back and the car stalled out again. I went back to the dealer and made them take the car back and refund my money. The next day I went in and talked to the dealer’s general manager and service manager. At this point they decided to go ahead and replace the ECM under warranty. So I got the car back last week with a bill of $0 thanks to the warranty and it seemed to be much better. For about 2 days.

For 2 days, it ran perfectly. Then the problem started up again. At this point though, the car won’t just stall out and refuse to start. The problem is so intermittent that the only thing it does is briefly lose electrical power to the engine while driving, at which point, the engine dies, but then power comes back and the engine re-fires and keeps right on going. All of this in the span of less than a second. It’s just enough to make the car buck momentarily, and then it’s fine. 

So now I’m figuring it must be an issue with ECM power or ground coming into the ECM. The ECM ground wire only travels about a foot from the ECM and attaches to the bulkhead near the wipers and it’s in fine shape, with no measurable resistance back to the battery. I also measured voltage at the back of the ECM harness while the car was running on both the ECM continuous power pin and the key-switched power pin. Good power at both, even when the car stumbles. 

To add to the confusion, the car did something strange just a few minutes ago. The car has been sitting in my garage since last night. Just now I went out to take another look at it. When I opened the driver’s door, the fuel pump cycled as if I had just turned the ignition on. The key wasn‘t even in the ignition. The pump just cycled on its own when I opened the door. I tried it again and now it isn’t doing it. Maybe this has nothing to do with my issues but I thought it was worth mentioning.

So what am I left with? ANOTHER bad ECM? That seems highly unlikely and I doubt the dealer would replace the ECM again under warranty given the circumstances. I’m stumped. If anybody has some real in depth experience with the electrical systems in this car and knows what might be causing this, please chime in. I don’t want to be a jerk, but if you don’t really absolutely know what you're talking about on this, please don’t. It’s not the O2 sensor, no matter what your mailman’s brother-in-law says.


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## rommeldawg (May 25, 2009)

fuel pump does cycle when you open the door, so everytime this car stumbles or fails both the epc and cel lights will not illuminate with key in position 2? is this a constant?


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## Anony00GT (Mar 6, 2002)

You need to be more specific with your voltmeter measurements. I've never in my entire life had a voltmeter say "good power" when testing a circuit. When measuring resistance between the ECU connector and battery ground (with the battery disconnected), there should still be some resistance due to the wires themselves (usually 1-2 ohms).

Can you post the full Vag-Com scan? Also, if the ECU is in fact losing power, it should clear out all the readiness monitors. When it runs, use Vag-Com to set all the monitors, and then after it dies, check the readiness status. If they're all "not ready", obviously the ECU did lose power.

Now...we do know that this is the 3rd ECU in this vehicle. We also know that a replacement ECU has fixed the problem, at least for now. So let's work on the assumption that the faulty ECU was a symptom and not a cause. Start by performing voltage drop tests (this works better than just a resistance test) on all powers and grounds from the ECU connector, see if you have any excessive voltage. Also check the wires/connections between the ignition switch and fuel pump relay.


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## barrishautomotive (Nov 11, 2011)

rommeldawg-
Ok... I wasn't sure about the fuel pump cycling. The car has done it a couple more times since yesterday so no worries there. Yes, the CEL and EPC light always fail to illuminate when the engine dies as a result of the ECM power failure. Any other time, they work fine. So in fact, as I'm driving along, the car will stumble for a moment, at which point the CEL and EPC do not illuminate, but then the ECM power returns, the engine restarts, and the lights illuminate for 2 or 3 seconds, then go out as the car restarts, just like they would if you were starting the car with the key normally.

Anony00GT-
Ok, the voltage at the back of pin 3 and pin 62 of the ECM both measured around 13.8 volts, the same as the battery with the engine running. The ECM ground wire measures 2 ohms back to the battery. 

I don't have the full version of Vag-Com (I bought the cheap Chinese cable) so I only have VCDS lite. There are severe limitations to what I can do with that program. I can tell you that the readiness monitors do return to "not ready" when this occurs.

I am glad to hear you say the ECM is probably a symptom, not the cause. I agree. The odds are just too slim that we happen to have a bad ECM for the 4th time (1 from the factory and now 3 replacements). I have already checked the wires and connection between the ignition switch and fuel pump relay. No visible issues. All the wiring looks brand new. I have not yet performed a voltage drop test on the ECM power wires. I'll start there and report back shortly.


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## barrishautomotive (Nov 11, 2011)

Ok, so I just performed a voltage drop test on the ECM power wires. With the engine running, measuring between battery + post and the back of the ECM harness, I measured 0.15 volts on pin 62, ECM constant power, and 0.017 volts on pin 3, ECM key switched power. They both seem reasonable to me. Thoughts?


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## barrishautomotive (Nov 11, 2011)

I suppose I should tell you how I know the readiness monitors show "not ready" after the issue occurs. The first mechanic I took it to was able to plug into it and see this while the car was at his shop. That's why he initially thought it was a bad ECM and referred me to the dealer. 

Also, worth mentioning. The dealer was able to pull a p0606 code (ECM processor fault) while the car was at the dealership. That is ultimately why the ECM got replaced. 

Both of those points may not be relevant, but you know...


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## Anony00GT (Mar 6, 2002)

You must be using VCDS shareware. You can register VCDS-Lite even with a Chinese cable for like $100. I believe that should give you access to basic settings, and other functionality. Just no hardware support from Ross-Tech. Anyway...

Those voltage drop numbers seem good to me. I'd do the same test on the ground(s) at the ECM (I don't have a wiring diagram in front of me, don't know offhand how many there are or exactly which pins are power/ground), and then do an old-fashioned wiggle test...grab and wiggle/shake the harness and see if there's ever any change.

There is a TSB out there that says any one of those 3 internal checksum error codes (IIRC P0604, P0605, P0606) can be caused by low power instead of a bad ECM. It instructs techs to be sure to diagnose any and all low power issues before ECM replacement. Just for kicks, do a complete electrical/charging test. Load test the battery (even though it's new), but more importantly do a complete test on the alternator, and be sure to check the diode ripple. Set the voltmeter to volts AC and see how much AC voltage you have across the battery with the engine running. I've seen alternators cause some really weird problems while still charging.


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## barrishautomotive (Nov 11, 2011)

Yeah, I'll update it at some point. I just don't want to spend the $100 right now. This isn't even my car!

I'll check the ground wires (pins 1 & 2) for voltage drop.

I've wiggled the crap out of everything trying to replicate my issue but I can't make it happen. That's the hardest part. The issue is intermittent and rare. Honestly, it's only occuring once every 20 or 30 minutes of run time. And it does it on its own. The car can be sitting in my garage idling and it will do it. Very random. Anyway, I'll wiggle the harnesses while I do the voltage drop tests just to be sure. I've read the TSB you're talking about. Battery voltage is above 12v. I can't say for certain what battery voltage was while the car was at the dealer and gave them the p0606 code. To be fair, I can't even be sure that the p0606 code happened at all. The dealer may have just told me that as a way of justifying replacing the ECM. It probably happened but I never actually saw the code myself.

Anyway... I will go ahead and check the electrical and charging systems. I have no problem running tests like these. The car has passed every test I can think of so far, so I need to track down a test it can fail. I'll run these tests at some point today, probably some time after the Broncos beat the Frogs (I am in Boise after all)

I'll let you know how it goes.


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## Anony00GT (Mar 6, 2002)

Try running wires (temporary, maybe out the hood and in the window) directly from the battery into the car so you can hook up a voltmeter and monitor voltage directly while driving. I'm still thinking it could be AC voltage spikes from the alternator wearing down and eventually killing the ECM. I could be way off base but it's a possibility that I've seen before and definitely worth checking.


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## barrishautomotive (Nov 11, 2011)

Well so much for Boise State beating TCU. Damn kickers... I guess I'll go run those tests now...


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## barrishautomotive (Nov 11, 2011)

Ok. I checked the ground wires for voltage drop and they were quite healthy, showing only .08 volts each. 

Now, somehow I'm getting strange results when I try to test for diode ripple. As soon as I set up my meter on AC and attach the probes to the battery terminals, I'm getting almost 28 volts AC. not millivots, 27.8 volts. With the engine off. Once I start the engine, I get a reading of 30.5 volts AC. Maybe I did the test wrong. Why would I be seeing readings like this?


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## barrishautomotive (Nov 11, 2011)

Ok. So my meter was just insane. I borrowed my dad's meter and rechecked. the highest reading I got was .022 volts. Seems well within spec. I also rechecked my previous measurements and they matched up with my previous findings. looks like the AC scale on my meter is junk. Good to know. So anyway...

Battery load test was good, 10.2 volts. Any other ideas?


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## fastinradford (Aug 3, 2010)

replace relay 109 and all 2 or 3 100s. and the 175.


that is your problem Im fairly sure


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## barrishautomotive (Nov 11, 2011)

fastinradford said:


> replace relay 109 and all 2 or 3 100s. and the 175.
> 
> 
> that is your problem Im fairly sure


This is what I mean by "if you don’t really absolutely know what you're talking about on this, please don’t. It’s not the O2 sensor, no matter what your mailman’s brother-in-law says." First, this car doesn't have a relay 109. AZG engine code, late 2001 model year. Second, and more importantly, all a relay does is supply power to various circuits. Since we've already established that the ECM is shutting off and that power supply is not the issue, it obviously is not a relay. A good mechanic doesn't just throw parts at a car on a whim. Again, I really don't want to be a jerk, but I'm looking for advice from someone who knows what they're talking about.


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## fastinradford (Aug 3, 2010)

never said 02 sensors, the relay 100s redistribute ignition switch signlas/voltage. ralay 109 (on 95% all ce2 and mk4 cars) controls voltage to ecu. relay 175 also has to do with voltage distribution durring starting.

but dude, I am just trying to help. there are far less knowledgeable people willing to help than me.

plus it was 2am on a sat night. lighten up man, DAMN


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## Anony00GT (Mar 6, 2002)

IIRC ECM power is supplied by the fuel pump relay on that car, and that has already been replaced.

You should technically have maximum 0.1v AC with the engine running, but i wouldnt condemn an alternator for only .2 volrs. Try the driving test I suggested earlier, see where AC voltage goes when the problem occurrs.

Use a regular 110v AC house outlet to verify the meter's AC functionality first.


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## Anony00GT (Mar 6, 2002)

Verify both meters with a known source, i just suggest a wall outlet cause its easy. Did you shut off and restart the car between tests? Is it possible you actually had ~30v the first time and then .2v the second?


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## squabeggz (Feb 20, 2009)

I am watching this thread with interest. I have also been dealing with an ECU issue. 16990 (P0606) I know it's quite different, but this thread is giving me ideas of what to check for causes. Aside from ECU replacement.

I have a 2001 jetta 2.0 AVH manual trans. 

Maybe it's Boise that ruins ECU's....I just moved away from there. CEL was on while I was still there, and I'm still chasing it..3 months later. 

Anyways, I assume you have checked ALL the grounds in the engine bay? (under the battery tray etc?) Also, there is the alternator wiring harness with its connector (right above the starter...also under the battery tray) that has been known to have issues with broken wires. The number one pin on that has a small wire that runs to the ecu. (small red wire, i believe)

I know it's not a solution, but they are quick and easy checks and could very well be the cause...or at least contributing factors.

Good luck.


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## barrishautomotive (Nov 11, 2011)

So it was quite a busy week and I haven't had a chance to post anything new in several days. Let's see...

Anony00GT - 
I verified that my orignal meter is junk, it measured pretty much the same numbers on my truck so it's going in the trash. The meter I borrowed from my dad is working fine. I did run a couple of wires back into the car and the highest AC reading I got on the drive was 0.025 volts. I think you previously said something about .2 volts not being too bad... It was actually .02 volts that I measured so it's well within spec. 

Also, the dealer supposedly replaced the fuel pump relay prior to me picking up and returning the car 2 weeks ago. After that, they replaced the ECM and gave me the car back. I made them refund my money after the replacement fuel pump relay failed to fix the problem. I'm not sure, but they may have removed the new relay and put the old one back in since in the end I didn't pay for a new relay. If it was a bad relay though, wouldn't that show up in the voltage and voltage drop tests of the ECM power supply wires? It still seems like the ECM is getting killed by some other electrical fault in the car and although I could be mistaken, I don't think a bad fuel pump relay could kill an otherwise good ECM, could it?

squabeggz - 

I appreciate the input but a visual inspection of the ground wires in question shows some good looking wires, and more importantly, a voltage drop test across the ground circuit would reveal any weaknesses in the ground wires if they existed so I don't think my problem lies there. I could be wrong though so I'll have a look over them again.


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## Anony00GT (Mar 6, 2002)

Yes 0.02 volts is fine, but what I'm looking for is what the alternator reads in AC voltage while the problem is occurring. I have seen alternators put out >30v AC when they have a rectifier problem, that's why I said to verify your meter. My thinking was that while you did that test drive the problem might rear its head.

I doubt a bad relay would kill the ECM, but it would cause it to shut down. You'd be able to see that on the meter...again, you'd have to have the meter on it when then problem happened.

The real problem here is that the issue is intermittent and can't be easily replicated, I'm assuming you never actually had a meter on anything while the problem was happening? I have to get to work...I'm gonna think about this for awhile and I'll post back later.


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## barrishautomotive (Nov 11, 2011)

Ok, let me clarify. The AC voltage test was done both at standstill and while driving. Tuesday, while driving, the car died and failed to restart, the CEL and EPC lights were not illuminated and the ECM appeared to be producing no output power. At that point, the AC voltage was zero, since the car wasn't running. When it runs, it produces .025 at most, when it stalls, zero. 

Also, I was able to confirm last week that the input voltage is still 12v or higher while the issue is occurring. Last week one of my tests was to backprobe each of the power wires at the ECM and wire them to hold a test relay open while power is being supplied, that way if the issue occurs, the relay closes and, in this case, blows a test fuse (I thought it was a pretty clever rig, actually). Eventually the car did stall but neither fuse blew, meaning that the ECM received continuous power throughout the test, otherwise the relays would have closed and popped my test fuses. I think that's pretty solid confirmation that the ECM is still getting full power at both the constant power and key-switched power sources at the moment the issue occurs.

Now, to be fair, I was never able to measure voltage drop across those wires while the issue was occurring, and I know that could still be an issue, but since there was enough voltage even during the issue to hold my relays open, I'm guessing there was enough for the ECM to stay powered on. 

That doesn't address a possible ground issue. Like I said, a voltage drop test from the ECM ground wires back to the battery show very little voltage drop while the car is running, but I was not able to complete that test at any point while the issue was occurring.

I suppose I could run my relay test on the grounds as well but I'm beginning to wonder if some other engine related component is causing my problems. I'm wondering if, for example a fuel injector could be drawing too much amperage. The injectors are grounded through the ECM, and increased operational amperage requirements could cause too much amperage to pass through the circuitry of the ECM and kill it, I would think. Really any component could do it. Maybe I'm way off, but it seems possible in my head at least.

As usually, your input is appreciated.


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## Anony00GT (Mar 6, 2002)

barrishautomotive said:


> I'm wondering if, for example a fuel injector could be drawing too much amperage. The injectors are grounded through the ECM, and increased operational amperage requirements could cause too much amperage to pass through the circuitry of the ECM and kill it, I would think. Really any component could do it. Maybe I'm way off, but it seems possible in my head at least.
> 
> As usually, your input is appreciated.


That does happen, however not in the manner of your problem, at least not that I've seen or even heard of. For example, in an A3 car, a cheap Chinese ignition coil can burn down injector drivers, and eventually kill the ECU. In some Audi (and maybe A4 cars?), shorted O2 sensor wiring can fry the ECU's throttle control logic...but in either case the ECU still powers up, and in the latter supplies throttle-related fault codes. However, AFAIK your problem is unique.

I wouldn't rule it out as a possibility though, however I don't know which component(s) to test though as I'm not familiar enough with the actual inner workings of the ECU.


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## squabeggz (Feb 20, 2009)

Anony00GT said:


> That does happen, however not in the manner of your problem, at least not that I've seen or even heard of. For example, in an A3 car, a cheap Chinese ignition coil can burn down injector drivers, and eventually kill the ECU. *In some Audi (and maybe A4 cars?), shorted O2 sensor wiring can fry the ECU's throttle control logic...but in either case the ECU still powers up, and in the latter supplies throttle-related fault codes.* However, AFAIK your problem is unique.
> 
> I wouldn't rule it out as a possibility though, however I don't know which component(s) to test though as I'm not familiar enough with the actual inner workings of the ECU.


I wonder if this is what is happening to mine? Everytime my ECU pops the 16990 (P0606), my throttle seems to reset (low speed surging etc.) Then when I clear codes, I get 17987 - Throttle Actuator (J338): Adaptation Not Started P1579 ...or... 17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting P1564. Ususally in that order. I try to run TB adaptation but it fails unless I run the engine for a couple minutes first, then run the adapt.

Battery checks out fine and I've also done the voltage drop tests mentioned earlier in the post.

Sorry to hijack...back to our original programming.


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## Anony00GT (Mar 6, 2002)

Barrishautomotive...You're going to have to run all these tests while the problem is occurring, I'm sure you're going to find something if you do. Other than that, I can't think of a way to get a definitive answer. I know it's a pain and it's gonna take some time, but I'm thinking that's the only way to figure it out.




squabeggz said:


> I wonder if this is what is happening to mine? Everytime my ECU pops the 16990 (P0606), my throttle seems to reset (low speed surging etc.) Then when I clear codes, I get 17987 - Throttle Actuator (J338): Adaptation Not Started P1579 ...or... 17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting P1564. Ususally in that order. I try to run TB adaptation but it fails unless I run the engine for a couple minutes first, then run the adapt.
> 
> Battery checks out fine and I've also done the voltage drop tests mentioned earlier in the post.
> 
> Sorry to hijack...back to our original programming.


Doubt it highly, but you can check your O2 sensor wiring visually if you want and make sure it's all intact. I think you have a power supply/ground problem.

Also check the battery with a good load tester (like a VAT40). Much better than the Midtronics junk that most people use. And a voltmeter is useless for battery testing, please don't tell me you're assuming your battery is good because your voltmeter told you it had ~12v.

If the battery and alternator are indeed confirmed good, get out the wiring diagram and find all the ground points for the throttle and ECU.


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## squabeggz (Feb 20, 2009)

I did do the multimeter test on the battery first..BUT...knowing that was far from absolute, took it to Les Schwab, Pep-Boys and AutoZone for many opinions. All 3 said battery was good, Pep and AZ also tested the alternator (on car test) and only Pep and AZ did load testing on the battery. Still, after doing some further research, I'm still not convinced that their tests were all that accurate. It's at LEAST a 4 year old NAPA battery, so I still suspect it. 

I've also checked all the grounds (under the battery tray and rain tray). I'll have to read and see where there might be some others that I've probabaly missed.


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## squabeggz (Feb 20, 2009)

Barrishautomotive...

Been doing some more reading online and found this little gem...Coolant Migration...Luckily it is not the cause of my issues. Super quick and easy to check for and rule out (hopefully). Basically, a bad design causes coolant to migrate through the wiring harness and causes all sorts of crazy electrical problems.


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## Anony00GT (Mar 6, 2002)

squabeggz said:


> Barrishautomotive...
> 
> Been doing some more reading online and found this little gem...Coolant Migration...Luckily it is not the cause of my issues. Super quick and easy to check for and rule out (hopefully). Basically, a bad design causes coolant to migrate through the wiring harness and causes all sorts of crazy electrical problems.


Ford had that same problem with brake fluid migration years ago. But to see fluid make its way all the way back to the fuel pump connector...wow.

My bet is that this is pretty rare, and I'm also willing to bet that any corroded connectors (or coolant in the connectors) would have been found by now, considering how many times everything's been disconnected...


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## squabeggz (Feb 20, 2009)

Probably won't help OP, but all my issues..including "Bad ECU" were caused by a faulty green top Coolant temp sensor. I replaced that with a new one and ALL codes went away. Passed emissions and have been CEL free for a month now. :thumbup:


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## advash (Aug 27, 2002)

squabeggz..

Can you clarify with some details of the issue you had and why you just decided to replace a temp sensor?


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## squabeggz (Feb 20, 2009)

http://forums.vwvortex.com/showthread.php?t=5480016

Basicly I determined that it was an electrical issue of some sort. Did alot of tests and checks on the electrical system...grounds, alt battery and wire harnesses etc...

Between eliminating simple things and using VCDS, the only code that was consistently showing up was the error in mapped engine cooling. Against my better judgement, I threw a part at it. (at this point, I was very frustrated. I had been dealing with this problem for awhile). It was an inexpensive part and easy to change. I swore this wasn't the problem because I had just changed it like 6 months ago. Well, it turned out it was the problem. The sensor I got before was faulty. (confirmed with tests from the bently). Essentially, I got lucky with an eventual hunch/educated guess.

Sent from my DROIDX using Tapatalk


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## nosborn94 (Feb 7, 2010)

*Thread Revival*

Did you ever solve this issue?


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## barrishautomotive (Nov 11, 2011)

Actually yes. It was in fact caused by coolant migration. The main ECM power wire was corroded and intermittently failing to supply enough power to keep the ECM powered on. After tearing down the harness and replacing that wire, the problem was solved. It was a nightmare to diagnose because it was so intermittent. If anybody reads this and is trying to diagnose a similar issue, the only recommendation I have is to open up the harness to inspect. Keep in mind though, this was a very specific issue. My ECM was losing power, which not only killed tbe engine, but the check engine light. That was the telltale sign. If your symptoms don't match mine exactly, you have more testing to do. 

Good luck!


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## nosborn94 (Feb 7, 2010)

*I found something*

So I had asked a while back about your solution. My car started having some more issues like yours. Unfortunately I panicked and took it to a mechanic in the neighborhood (bad move) because it was dying pretty frequently. Once on the freeway on ramp but as usual it would turn back on after a minute or two. The mechanic concluded that the engine was quitting on me after some compression tests. Well of course, its old but that's not the problem. $200 diagnostic fee and he found nothing. And to add to that he told me that it was fine. Come on bro, obviously its not ok if it dies on me twice in one day.

Anyways. I started to think it was more likely an ECM issue. So today I pulled off the connector and found this. Corrosion on the pins. I can only assume this is my issue. 

What do you guys think?

Are the corroded pins related to power or timing or anything of that matter?

You can see the corrosion in the pics. Pin 86, 87, and 115 have corrosion on them. 86 is the worse.


You can the corrosion on 115 better in this pic


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## Anony00GT (Mar 6, 2002)

You know what happens when you ASSuME, right? 

Clean up the corrosion on both sides of the connector and see what happens. Even if that's not your issue, it certainly can't hurt.


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## MikeTheCPA (Feb 16, 2009)

*Possible solution?*

I had similar troubles with my daughter's 2001 Jetta. See my post here:

http://forums.vwvortex.com/showthread.php?6999980-Weird-electrical-problem!

Hope it helps!

Mike


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## nosborn94 (Feb 7, 2010)

MikeTheCPA said:


> I had similar troubles with my daughter's 2001 Jetta. See my post here:
> 
> http://forums.vwvortex.com/showthread.php?6999980-Weird-electrical-problem!
> 
> ...


Thanks. Is there a way to diagnose whether the ignition switch is bad or not?

One other thing is that sometimes, when I go to open the car with the clicker the car acts as if the battery is real low and sometimes the engine won't start when it does that. But of course it will start soon after.


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## MikeTheCPA (Feb 16, 2009)

*Throwing parts at the Jetta!*



nosborn94 said:


> Thanks. Is there a way to diagnose whether the ignition switch is bad or not?
> 
> One other thing is that sometimes, when I go to open the car with the clicker the car acts as if the battery is real low and sometimes the engine won't start when it does that. But of course it will start soon after.



We had the same problem with starting. I don't know how to test the switch. I was just throwing parts at the problem based upon the mechanics tests & recommendations. The ignition switch I referred to is connected to the back of where the key goes in to start the car. You don't have to change the key or anything. Just the electrical connector. The part can be purchased for $15 here http://www.onlinewholesaleparts.com/is001.html  or at your local auto parts for around $60.

You can follow this thread to replace it... http://forums.vwvortex.com/showthread.php?2466896-**Ignition-Switch-Replacement-DIY** 

If you do this replacement, be sure to check the wiring for burnt spots or areas that may need replaced or taped.

I'm not sure if this was the part that fixed my problem or the cumulation of all the parts I paid for? The Fusible Link Box Assembly and battery cables have been replaced by a lot of owners. I feel better that they have been replaced. The alternator was probably fine on my car?

thanks,

Mike


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