# Wideband Conversion Radiator Fan Issues



## 20v master (May 7, 2009)

Back story: I did the wideband conversion last January in my 01 AMU TT225 using a VW AWP ECU. Since it was winter, I didn't notice the fan/overheating issues until the weather got warmer, ie summer. AC worked, but only the small fan would come on. Sitting in stop and go traffic would cause coolant temps to climb, so that's what notified me of an issue. I assumed fan control module and installed a known working spare, but no dice. Turns out the large fan was dead and wouldn't turn even with straight power to it, so I replaced the fan about a month ago. When AC was on, both fans spun at high speed, so I thought that took care of my issue. Well I left my wife sitting in the car while I ran into a store the other day, and being a woman, she got cold and turned the air off. We were in Florida at the time, so when I came back out 10 minutes later, the temp needle was 7/8th to pegged out. I clicked the HVAC controls to 49C and saw 111*C, with no fans running!!!!! So I switched the AC on and cranked the defrost on full heat, got the temps back down to normal, and started doing some research. Now I see several people have mentioned disabling/removing/cutting pin #61 to the ECU to address fan issues on wideband conversions. 

*Has anyone who has done a wideband conversion on an AMU 225 had to modify pin #61 in the ECU harness to get the fans functioning properly?* 

http://newbeetle.org/forums/technical-modifications/55524-aph-awd-ecu-swap-conversion.html The last post shows a guy mentioning.... "Tonight will snip ecu pin 61 to make the rad fans not constantly turn" but I don't have constantly turning fans. 

http://forums.fourtitude.com/showthread.php?6112137-gt-gt-gt-Unitronic-Wideband-ECU-Conversion-Harness-lt-lt-lt&p=83953643&viewfull=1#post83953643 The next to last post mentions moving the wire from pin #61 to pin #41 to deal with this issue. 

I don't see the issue mentioned much in the 1.8T forum since they're all using VW ECU's, so I'm wondering if something is different between the 225 ECU and the VW ECU's for fan control that I'm missing. Any insight and help is apprceciated. :beer:


*UPDATE: I removed wire/pin #41 and put it in slot #62 on the larger ECU connector, and now the fans kick on with AC off at 98*C and run until coolant reaches 96*C. :thumbup:*


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## 20v master (May 7, 2009)

Similar discussion going on HERE


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## 20v master (May 7, 2009)

I "think" I found the answer HERE with differences in pin outs between AWD and AWP ECU's. I don't have my TT Bentley handy but will have a buddy send me the wiring diagram tonight and compare to the AWP wiring diagram. If it looks like this is right, I"ll swap the wires and report back.


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## 20v GTI Guy (Aug 20, 2001)

My car runs like this right now. I bought the car with the wideband conversion already done, so I had no idea that this could even be causing this to happen. 

I'll check my pins on my ecu as well.


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## 20v master (May 7, 2009)

:thumbup:


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## hunTTsvegas (Aug 27, 2012)

Just as soon as my stuff arrives from GTS, I'll be undergoing this process as well. In for consolidated information. I've got my Bentley at home if you need any assistance as well. :beer:


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## 20v GTI Guy (Aug 20, 2001)

Well I busted out the bentley and started tracing the wires to my ecu and honestly I'm having a hard time following the wiring diagram to pinpoint what wire is what. I need a lesson on reading these schematics again. I've done this a few times and forget every single time I finish what I'm doing. 

I think I remember that the ecu itself is numbered at every pin, so I plan on pulling that and seeing what wire is going where.


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## 20v master (May 7, 2009)

Didn't get to testing wire #61 this weekend due to weather and other life obligations. Will try again this coming weekend.


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## Doooglasss (Aug 28, 2009)

20v master said:


> *Has anyone who has done a wideband conversion on an AMU 225 had to modify pin #61 in the ECU harness to get the fans functioning properly?*



I can't remember the pin number but in my mind it was 57 or 67. I'd have to look at my old build thread that was blackholed (I have a PDF). My issue before removing this wire was that the fans were stuck ON and the car couldn't get up to temperature. I believe on my ECU (out of an AWP) that pin was a power wire for the EGT probe. This is all if my memory works- I do smoke a lot of crack these days.


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## 20v master (May 7, 2009)

Doooglasss said:


> I can't remember the pin number but in my mind it was 57 or 67. I'd have to look at my old build thread that was blackholed (I have a PDF). My issue before removing this wire was that the fans were stuck ON and the car couldn't get up to temperature. I believe on my ECU (out of an AWP) that pin was a power wire for the EGT probe. This is all if my memory works- I do smoke a lot of crack these days.


The crack you're smoking must be good, because there is no EGT probe on AWP's, but there is one on BEA's.  What ECU are you using? My issue is that the fans don't kick on when temperatures climb unless the AC is on.


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## 20v master (May 7, 2009)

Update: I removed wire/pin #41 and put it in slot #62 on the larger ECU connector, and now the fans kick on with AC off at 98*C and run until coolant reaches 96*C. :thumbup:


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## formerly silveratljetta (Feb 6, 2007)

I just did a wideband conversion on an 01 Audi TT AMU and I am having the same issue of no radiator fans even with the AC turned on.

I will try swapping pin 41 into slot 62 and report back with issues.


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## 20v master (May 7, 2009)

formerly silveratljetta said:


> I just did a wideband conversion on an 01 Audi TT AMU and I am having the same issue of no radiator fans even with the AC turned on.
> 
> I will try swapping pin 41 into slot 62 and report back with issues.


Saw your posts in the 1.8T forum but never saw this. I think this is a specific difference between different ECU's, as the issue I had wasn't what Doug and yourself and others have gotten after doing the wideband conversion. I know you're looking for the AMU wiring diagrams, but my TT Bentley is 100 miles away so I can't help with that for a few weeks. My issue wasn't constantly running fans or compressor that wouldn't engage, my only problem was that the fans wouldn't run without the AC on. So if climate control was off, no fans regardless of engine temps. You're using the AEM ECU, so not technically an AWP ECU, but it's supposed to emulate the AWP ECU?


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## formerly silveratljetta (Feb 6, 2007)

20v master said:


> Saw your posts in the 1.8T forum but never saw this. I think this is a specific difference between different ECU's, as the issue I had wasn't what Doug and yourself and others have gotten after doing the wideband conversion. I know you're looking for the AMU wiring diagrams, but my TT Bentley is 100 miles away so I can't help with that for a few weeks. My issue wasn't constantly running fans or compressor that wouldn't engage, my only problem was that the fans wouldn't run without the AC on. So if climate control was off, no fans regardless of engine temps. You're using the AEM ECU, so not technically an AWP ECU, but it's supposed to emulate the AWP ECU?


Yes the AEM ecu is supposed to function just like an AWP ecu.

Max is trying to get a hold of Doug to get the Bentley manual so we can get this solved once and for all.


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## trouble4 (Jun 19, 2015)

check also part # 5K0959126 High pressure switch for A/C for AMU engine code


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## formerly silveratljetta (Feb 6, 2007)

trouble4 said:


> check also part # 5K0959126 High pressure switch for A/C for AMU engine code



I don't understand what effect that would have because the AC was working fine prior to the wideband conversion.


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## ramone23456 (Dec 29, 2009)

*AMU*

20V Master,
I have an AMU and am about to start my wideband conversion.
Would you suggest that I do this at the outset:
UPDATE: I removed wire/pin #41 and put it in slot #62 on the larger ECU connector, and now the fans kick on with AC off at 98*C and run until coolant reaches 96*C. 

Has this worked out fine for you?
Thanks.


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## formerly silveratljetta (Feb 6, 2007)

ramone23456 said:


> 20V Master,
> I have an AMU and am about to start my wideband conversion.
> Would you suggest that I do this at the outset:
> UPDATE: I removed wire/pin #41 and put it in slot #62 on the larger ECU connector, and now the fans kick on with AC off at 98*C and run until coolant reaches 96*C.
> ...


I would advise not to swap any pins until you have done the conversion. Report back with how the fans are behaving with the pins in stock positron.

If fan behavior is not good then swap 1 pin at a time and report back with results. Keep track of the stock location of each pin.


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## ramone23456 (Dec 29, 2009)

formerly silveratljetta said:


> I would advise not to swap any pins until you have done the conversion. Report back with how the fans are behaving with the pins in stock positron.
> 
> If fan behavior is not good then swap 1 pin at a time and report back with results. Keep track of the stock location of each pin.


Good point. That will be my approach.
Thanks.


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## 20v master (May 7, 2009)

ramone23456 said:


> 20V Master,
> I have an AMU and am about to start my wideband conversion.
> Would you suggest that I do this at the outset:
> UPDATE: I removed wire/pin #41 and put it in slot #62 on the larger ECU connector, and now the fans kick on with AC off at 98*C and run until coolant reaches 96*C.
> ...


It has, but like Richard said, see what it does after the conversion. He had totally different symptoms than I did. Richard, did yours start working again after removing the AEM?


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## formerly silveratljetta (Feb 6, 2007)

20v master said:


> It has, but like Richard said, see what it does after the conversion. He had totally different symptoms than I did. Richard, did yours start working again after removing the AEM?


I never tried to start the car with the stock ecu again because of the 80mm throttle body.


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## demarioii (Jul 29, 2015)

01 AMU tt 225 here.

i have pulsing fans with the wide band swap until i remove the 30amp fan fuse from the fuse box on top of the battery fuse #1 in line.

i put #41 in #62 this is not right. That just blew the engine timing 15amp fuse. this thread below said to just remove #61 which is the white pin directly next to #62. so i think #62 was written in error. I'll try tomorrow since i went back to narrowband for the night. 


http://forums.vwvortex.com/showthread.php?7098332-Unitronic-wideband-ecu-harness-in-TT


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## 20v master (May 7, 2009)

I"ll pull back my harness tonight and confirm, because other's have gotten different results than mine and now yours as well.


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## formerly silveratljetta (Feb 6, 2007)

demarioii said:


> 01 AMU tt 225 here.
> 
> i have pulsing fans with the wide band swap until i remove the 30amp fan fuse from the fuse box on top of the battery fuse #1 in line.
> 
> ...


Pin 62 has nothing to do with the fans.

Put everything back to normal and start by disconnecting pin 61 ONLY.

Let the car warm up and see if the fans kick on once the car is idling at operating temp.


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## demarioii (Jul 29, 2015)

formerly silveratljetta said:


> Pin 62 has nothing to do with the fans.
> 
> Put everything back to normal and start by disconnecting pin 61 ONLY.
> 
> Let the car warm up and see if the fans kick on once the car is idling at operating temp.


I found that out quickly. I'll try this tonight and update.


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## demarioii (Jul 29, 2015)

Wideband swapped again and pulled pin 61. Everything is working as it should.


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## racin2redline (Sep 25, 2008)

demarioii said:


> Wideband swapped again and pulled pin 61. Everything is working as it should.


what does pin 61 actually do? 

right now there seems to be a bit of confusion and conflicting info with the swap with the amu. 
i still dont have my ecu back so no nay to know how my car will react. 



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## demarioii (Jul 29, 2015)

racin2redline said:


> what does pin 61 actually do?
> 
> right now there seems to be a bit of confusion and conflicting info with the swap with the amu.
> i still dont have my ecu back so no nay to know how my car will react.
> ...


I'm not entirely sure since i've searched for days with no luck of finding a pin out on any Bosche 7.5 ME ECU, let alone one specifically for the AMU early narrowband TT's. What i do know is, #62 is 12v power and has nothing todo with the rad fans. i believe that one thread where the guy said he fixed his problem by swapping or pulling that pin is false or a different layout ecu. The only other case i saw with someone saying they had fan issues with the AMU swap was in the conflicting thread where he said he just pulled 61. That is what i did and my fans work as they should now. Maybe this pin sent conflicting voltage to the fan circuit using the wideband ecu?


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## racin2redline (Sep 25, 2008)

did you have power at pin 21? 

just got my wideband ecu for my swap back, tried to start the car, after 1st attempt ecu lost connection (no cel on the dash). the ecu only connects to vcds after i unplug it and plug it back in
tuner said check to make sure pin 21/has power


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## BeasTToftheEast (Sep 20, 2007)

I'm not having fan issues as well. The fan control module is making noise and the fan won't come on. Any input would be great as this is the last thing needed to be addressed before I can break the motor in.


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## racin2redline (Sep 25, 2008)

idk I didn't change any pins around . my fans work like stock 
maybe it's something needs to be done on the ecu flash? 

my ecu loosing connection was also an ecu flash error that was corrected 

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## racin2redline (Sep 25, 2008)

having a similar issue now out of nowhere . what is bugging me is I know for a fact the fans were all working .. one day during August .. no more fans. 

the secondary water pump doesn't even kick on with the car off. 

replaced the fan control module with no change..

I guess I'll pull the ecu and test power to the pin.. any other ideas ? 

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## lite1979 (Sep 9, 2005)

How does the fuse tray on top of the battery look? If the contacts get corroded or start to melt, the fuse won't make contact and you'll have no fans at all...


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## racin2redline (Sep 25, 2008)

lite1979 said:


> How does the fuse tray on top of the battery look? If the contacts get corroded or start to melt, the fuse won't make contact and you'll have no fans at all...


fuse looks fine , checked it multiple times.
have no fans at all. none with a/c either , no after run pump 

idk why everything would work then stop working, without blowing a fuse or melting a wire or something? 

possibly the temp sensor on the radiator is bad? CTS throws a code most of the time. its a green top sensor.. I guess I can try replacing that . 

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## lite1979 (Sep 9, 2005)

The radiator fan switch is for low-speed and A/C afaik. Mine's dead right now and I still have high speed fans and the after-run coolant pump operating correctly, but no fans with A/C on and no A/C unless I jumper pins 1&2 on that switch's connector...

Edit: Looks like just the low temp part of mine is hosed; the radiator fan switch does both:

http://www.germanautoparts.com/productdisplay/108161


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## racin2redline (Sep 25, 2008)

lite1979 said:


> The radiator fan switch is for low-speed and A/C afaik. Mine's dead right now and I still have high speed fans and the after-run coolant pump operating correctly, but no fans with A/C on and no A/C unless I jumper pins 1&2 on that switch's connector...
> 
> Edit: Looks like just the low temp part of mine is hosed; the radiator fan switch does both:
> 
> http://www.germanautoparts.com/productdisplay/108161


so if this were dead it looks like the fans might not turn on without a coolant temp signal 

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## racin2redline (Sep 25, 2008)

anyone 

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## lite1979 (Sep 9, 2005)

I'll be replacing mine Tuesday...

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## racin2redline (Sep 25, 2008)

Getting frustrated with this 

Just pulled pin 62 after reading that quick .

That's just 12v ecu doesn't even get power without that. 

Pulled pin 42 . Not sure what that did but still no fans 


Will try putting it all back to the way it was and just pull 61 and see what happenes


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## racin2redline (Sep 25, 2008)

Just pulled pin #61 white wire and pulled the fuses on top of the battery and the FANS WORK  




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## ImOldGreggg (Feb 3, 2017)

I just swapped my 02 AMU to a AWP ECU from another TT for my wideband conversion and I dont have any low speed fans. I made sure to get it up to operating temp and they still dont with climate control on. They did work prior to the ECU swap, I also was going to checkout the #61 pin everyone removes and found out I dont even have that pin!


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