# TBA Error in VCDS



## cmdshft (Oct 17, 2011)

*Throttle Adaptation Error + Idle Bounce after throttle*

Hello. This is for a MK3 1997 OBD-II Volkswagen Cabrio 2.0L 5 speed.

Recently, I replaced some important parts for my car, namely a full clutch replacement, clutch cable replacement, crank breather return and various other thing and decided to scan the ECU for fault codes. Took my car to a friend of mine that has the VCDS software and we found error DTC P1544 "Throttle Actuation Potentiometer Signal Too High." We researched the answer for it and attempted to do a proper TBA and VCDS returned an ERROR response. We followed the guide on the Ross Tech website for a proper TBA procedure. We figured it was time for me to replace the TB, so I did. I received my replacement part, which was a used TB from a junk yard, installed and VCDS is still returning an ERROR response.

About a week or so before I installed the replacement unit, 

About two days prior to the new TB install, my alternator crapped out and the car died while driving home from work and had to get towed home. I installed the new alternator the next morning and everything was fine up until after the new TB was installed.

The car drives fine otherwise, with the occasional bouncing rev when I disengage the clutch and it idles higher than I believe it should, around 1100 RPM.

[video]http://tinypic.com/r/rgz6uo/5[/video]

I've searched around for a while and I see a mix of different solutions and whatnot.

I remember that a while before having discovered this issue, I decided to actually clean the old TB and the MAF using the respective cleaners for them individually (I had a higher idle but never had a bouncing idle as shown in the video until after the new TB was installed).

Some solutions say that the ECU could be bad. I've checked the harness at where it connects to the ECU as well as where it connects by the trans. Nothing seems to be corroded or dirty. Could it really be possible that this used unit was basically as shot as my old TB was? At this point, I am willing to pay full price for a new TB, which as of late is running ~$300 (ouch).

Some also suggest to disconnect the battery terminals and connect them together for about 1 minute to "hard reboot" the ECU to default and it MIGHT reset all the idle values, which I honestly have not tried yet but I have very little faith this would work as intended either.


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## cmdshft (Oct 17, 2011)

Bump. Nobody has an idea?


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## cmdshft (Oct 17, 2011)

bump. Added a link to a video of the bouncing idle in the first post.


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## Anony00GT (Mar 6, 2002)

Post a full auto-scan please, since you have VCDS, so we can see the whole story of what's going on. Then clear all faults, perform ADP, and if field 4 again says ERROR, re-scan and post code(s).

Have you tried performing the throttle ADP with the throttle cable disconnected?


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## cmdshft (Oct 17, 2011)

I personally don't have VCDS, my friend does but I schedule with him when our free time matches up so it might be a while before I can post a scan. We did a few scans and it's only the same code that comes up that I posted above. We did not try adapting without the throttle cable attached though.

After a few days of this issue, I noticed that it only happens after the car is fully warmed up. If it's warming up or cold and I give it some gas, it continues on as normal. I don't have the hot air return installed either, so in the cold it's a little rough but never stalls, after warming up it's all good until as I said above.

However, this morning I decided to tackle the issue a bit. I took apart the air intake, disconnected the two vacuum(?) lines going from the airbox to the manifold and itself, disconnected the one from the plenum, took off the main intake tubing, disconnected (what I think is) the idle air line (the tubing which connects to the large brass fitting that dumps air into the plenum side of the TB valve, is this the EGR though?), fiddled with the butterfly valve to make sure it has some back play as I have read elsewhere and then put it all back together and made sure everything was as tightly sealed as can be.

This seemed to correct the bouncing idle issue A LOT. I took it out for a decent drive where I could really get on it, still drives fine, however, I still have a random bounce when disengaging the clutch but it's NOWHERE near as bad as it was before doing so. I did not do another scan for DTC's but I do think I am smelling the engine running a tad rich now, so I think an O2 sensor went bad.

It still idles around 1100 RPM after full warm up, though.

My plan now is to just buy a brand new throttle body, as I bought the replacement used as I said, likely I just happened to have some bad luck and received a faulty unit. Also going to replace the O2 sensors and probably even change the MAF even though I am not throwing a MAF code just to be safe.

I read something about the ignition coil being bad, I plan on replacing it with a BFI unit anyway later on but the current one looks to be okay, I don't see any cracks or anything. The wiring looks good too. No issues with cranking or starting, never stalls out.


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## Anony00GT (Mar 6, 2002)

I wouldn't recommend replacing anything until a full and proper diagnosis is performed. Throttle body failures are rare.


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## cmdshft (Oct 17, 2011)

Okay, currently trying to change the O2 sensors. There is now a weird smell, almost like rotten eggs. Can't be the cat, it's brand new, so I think a sensor or both may be shot and causing bad fuel and bad idle.

They are being a royal pain so I am about to whip out the trusty blow torch after I take a break from sweating trying to break them loose with my O2 wrench. :banghead:

EDIT: So after 3 hours, for some reason I could not convince the sensors to break loose. I don't know how my mechanic managed to change my cat if I can't even get them to come out after some wrenching with a proper O2 wrench, some PB Blaster and a butane torch... Of course, I don't have access to a lift like he did so maybe that's what I need for some serious "convincing."

However, during this time, I am more and more convinced that the issue is purely the throttle body(s). If I remember, we did not replace the TB gasket... I've seen some people get lucky and get away with it but since this idle bounce is more symptomatic of a vacuum leak, my guess is that the seal in the TB is poor enough to leak enough air to cause this idle bounce randomly as it only occurs after throttle is applied and the motor tries to rebound from the drop in RPM while returning to idle. There's not enough justification of any other vacuum leaks as this bouncing started IMMEDIATELY after installing this used unit.

Also, the weird smell is gone. Talk about a love-hate relationship, right?


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## cmdshft (Oct 17, 2011)

I was able to replace the O2 sensors to make sure I wasn't having any other trouble codes show up so I could attempt an adaptation. I bought a brand new throttle body from ECStuning, installed it and I am still having the same issue.

Checked for DTC codes and it's P1544 - Throttle Motor signal too Large.

DTCsearch shows this: http://www.dtcsearch.com/P1544/Volkswagen/

"Throttle motor position high input"

Says cause is "wiring short to positive, throttle motor position sensor."

Does this mean that I need a new ECU/engine harness/both? Should I just replace both and call it a day? Is there a way to fix this code without replacing any more parts?

I'm actually really annoyed with this... Any help would be appreciated.

Also, I checked the distributor and the coil as I saw in some other threads and so far they aren't arcing or melting. Car starts fine, drives fine, this only happens when it's idling.


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## Anony00GT (Mar 6, 2002)

You are using a proper, genuine VCDS interface or dealership tool to perform the adaptation, right?

Clear all codes, attempt adaptation again (01-04-098), then when it fails, perform an auto-scan and post the whole thing so we can see the VAG codes and other module info.


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## cmdshft (Oct 17, 2011)

Yes, we're using the cable right from ross-Tech and latest VCDS. When I can, I will get the scan info and post it.

Might toss an ECU at it and see what happens later this week.


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## Anony00GT (Mar 6, 2002)

DO NOT replace the ECU until proper diagnostics are performed. If the ECU was ruined by a short or something, you need to figure that out first, or you might smoke the new ECU. This is much more likely in MK4 cars, but still.


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## cmdshft (Oct 17, 2011)

Here is the full scan that was run (took about 10 minutes to do):

Thursday,03,April,2014,13:40:03:51368
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.2.0
Data version: 20140212


VIN: 3VWAA81E2VM806661 License Plate: 



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 1V - VW Golf Cabrio (1997 > 2002)
Scan: 01 02 03 08 15 25 35 56

-------------------------------------------------------------------------------
Address 01: Engine Labels: 037-906-259.lbl
Part No: 037 906 259 P
Component: MOTRONIC M5.9 HS V01 
Coding: 00002
Shop #: WSC 00066 
VCID: 29572CF1D3318A56EC9-4B4A

1 Fault Found:
17952 - Angle Sensor 1 for Throttle Actuator (G187) 
P1544 - 35-00 - Signal too Large
Readiness: 0110 0101

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 6N0-909-60x-VW2.lbl
Part No: 6N0 909 603 D
Component: AIRBAG VW2 V00 
Coding: 00068
Shop #: WSC 00066 
VCID: 336BCE9901FDC086565-4BB0

1 Fault Found:
00588 - Airbag Igniter; Driver Side (N95) 
32-00 - Resistance Too High

End ---------------------------------------------------------------------


Any help would be great. We went through the harness at all the common failure points and then all the other areas and we couldn't find corrosion or breaks in the wiring. I suspect it may be the ECU in this case. A actual VW tech says to simply swap an ECU out and see what happens.

My ECU part number is in the scan.

We also attempted to to a TBA with the trottle cable disconnected, still no go. Continues to display ERROR.

Also, I have a cracked evap canister. Would that be enough to cause an idle bounce? It's a pretty big hole, there is no code being thrown for the purge valve.


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## Anony00GT (Mar 6, 2002)

Remove the throttle body from the car, and remove the black plastic cover. Spray electronic parts cleaner in there and manually sweep the throttle a bunch of times, clean any crap off the pots. Then retry the ADP.

If that doesn't work, use a meter to verify all wiring between the throttle body and ECU. If it all checks out, replace the ECU and try again.


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## cmdshft (Oct 17, 2011)

Anony00GT said:


> Remove the throttle body from the car, and remove the black plastic cover. Spray electronic parts cleaner in there and manually sweep the throttle a bunch of times, clean any crap off the pots. Then retry the ADP.


This is a brand new throttle body.



Anony00GT said:


> If that doesn't work, use a meter to verify all wiring between the throttle body and ECU. If it all checks out, replace the ECU and try again.


I've a friend that works as a Service Manager at VW now, so I am just going to take it to him and see what he can do. I've about reached the limit of my patience, given that this is my only car and I cannot keep taking days off to take it somewhere. I need it diagnosed and fixed in one shot and over with.


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## Anony00GT (Mar 6, 2002)

cmdshft said:


> This is a brand new throttle body.


Is it?



cmdshft said:


> I received my replacement part, which was a *used TB from a junk yard*,



Either way, keep us updated when you get a final diagnosis :beer:


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## cmdshft (Oct 17, 2011)

Anony00GT said:


> Is it?





cmdshft said:


> I bought a brand new throttle body from ECStuning, installed it and I am still having the same issue.


So yeah. My friend is gonna take it to the dealer this week that he works for and will see if we can solve it.


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## bangin_brent (Mar 7, 2014)

Make sure your ground cable is plugged all the way in on the throttle body, and check the rest of the main grounds.

_Posted via *Topify* on Android_


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## cmdshft (Oct 17, 2011)

Tech was able to repair the wire and adapt the throttle body. All is well now.


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