Throttle Body Wiring

[sirminder]

Hey Guys,

I am trying to figure out if I have a bad ECU or problem with the wiring harness to the Throttle Body.

The image below indicates to test for 5v across 2+Ground and 5v across 2+6.



My results are 3.8v across 2+Ground and 3.8v across 2+6.

If checking for continuity, what should I get across 2+Ground and 2+6? (none correct? 2 carries the "+" and 6 the "-")
When I check across 2+Ground I get 20ohms and 2+6 is also 20ohms. But, 6+Ground I get about 3ohms.

Please, can someone verify this with and let me know? I do not have a Bently manual to follow to the next troubleshooting step listed on the image. All I have is a cheap Chilton manual and a friends Vag-Com. I will be disconnecting the ECU to check end to end continuity on the wiring harness and confirm if the same ohm readings listed above are at the ECU.

This whole mess is from 3 different TB's not wanting to do an adaption. I get a high pitch sound and a bit of crackle just like in this thread. Voltage from new battery is 12.20 with ignition on, so I know its not that. I've cycled the ignition many times and disconnected battery cables to reset everything by:

1) Remove both the Positive and the Negative battery terminals from the battery.

2) Wait 15 seconds then touch the 2 battery leads together for 10 seconds then separate (this imitates the same capacitor discharge that is involved with the Vagcom reset)

3) Re-attach the terminals to the battery.

4) Stick key in ignition and turn to ON (DO NOT START THE CAR) and leave in this position for 30 seconds to allow the newly reset computer to re-learn the parts of your vehicle.

I'll post the DTCs shortly. But, at some point, I would get the same codes (3 of them) with or without the TB being connected.

I am no expert, but this leads me to believe I have an ECU or Wiring issue.

Please, feel free to chime in with your expertise and thanks in advance!

[a4darkness]

Been dealing with this same issue for a while now.

TB hard code [17987 - Throttle Actuator (J338) P1579 - 001 - Adaptation Not Started] which will not clear.
Swapped in a new TB, no change. Reset, rebooted, retested everything, no change. Swapped in another (immobilized) ECU, still no change and the code was still there.
At this point, all tests run thus far point to wiring between the TB and ECU as the issue.

As diagnosing electric issues is not my strong suit, Tim/tchuck was cool enough to provide the following marked up schematics to test the wiring. Was planning on taking a crack at this on Saturday, hopefully these will help you out as well.

[a4darkness]

And here's the ME7 ECU Pinout as well.

[tchuck]

Not sure if I mentioned this but you aren't likely going to see zero ohms like I drew on the cartoon meters. It should be really low, but the real value of the impedance test is finding an infinite or really high resistance (no/bad continuity) that would indicate a break in the wire.

[sirminder]

Wow, many thanks!! This really helps in trying to track down where the issue is.

The other ECU you swapped in, where did you source that from? I do not have a spare and need to look for options if I need a new ECU. Ecurepairnow quoted me $350 to test, repair my bad ecu. Or, $100 to re-code a used ECU, but I need to find a good working ECU first. They also offered to only test my ECU for a small fee.

Hopefully, you will be able to narrow down your problem soon too!

[a4darkness]

I'm glad you started a thread about this, wanted to do so myself after I figured out WTF the problem is.

We're certainly not the 1st people to have had this issue. It's somewhat common and often times there are no solutions to the underlying issues in the threads. Pretty frustrating. Yeah, usually it's due to a bad TB and sometimes it can be wiring or even the ECU but there's rarely any details about it. I've spent hours and hours searching online for answers but haven't come up with much. K-line stuff usually comes up, which I initially suspected / investigated as well but that wasn't it either. This has been a long diagnosis.

This is the only thread I found detailing problems of a similar character which resulted in success by replacing the ECU.
http://www.passatworld.com/forums/b5...ody-error.html

As for the ECU I used, that came from a close friend back in NorCal. It's an APR I flashed ECU but wasn't de-immobilized so obviously the car wouldn't start. However, after cycling it in and attempting to clear codes, the [17987 - Throttle Actuator (J338) P1579 - 001 - Adaptation Not Started] appeared as well which lead us to believe that the issue was not ECU related but actually the wiring to <-> from the TB to the ECU. (Prior to this, we pulled the TB out of my car, plugged it into another B6 and the adaption ran just fine.)

So right now it's looking like wiring or possibly a connection issue. Cleaned the TB plug contacts with contact cleaner spray as well... no luck there either. Prior to all this mess, I'd only pulled the ECU cover one time to install a Podi. We also inspected / swapped the relays and wiring in the box as well, all of which is fine. Figured I'd mention all this for you OP / anyone else looking to thoroughly troubleshoot this issue.

[sirminder]

Yes, frustrating indeed to say the least. After weeks of trying to figure what is going on, I gave the reset procedure another try. This time, I unplugged the accelerator pedal and left the key in the ignition on position. Upon connecting the battery back, the throttle body began doing its adaptation process, but the crackling was still there. Plugged the accelerator cable back in and gave it a try. Weird enough, it fired right up and idled normally. However, the EPC and traction control lights where on, but no engine light. I let it idle for 5 minutes and turned the engine off/on and went for a short spin. Shortly after, both of the EPC and traction lights went away. YES, great success! like borat, I thought. Went back home and left it at that. Next day, no luck. I couldn't even get the engine to stay on and was misfiring like no tomorrow.

I gave up and had a mechanic take a look. A week passed and he kept getting codes related to the accelerator and suggested I try a new one. It kind of made sense to me, since I did have a bit of success when I unplugged it and plugged it back in. However, the new pedal did not make a change to the car, but only to my wallet. Took the car back home, closed the garage and had a drink.

Finally, I had a bit of time and decided it was time to pull the ecu. Once I reached the connections, I noticed some sort of liquid substance on the harness and below the relays. But how could this be? I thought. This car hasn't been touched by water or rain in months.



Took a closer look and it was definitely coming from the ECU.




This is good! I think I have found the culprit! Knowing is half the battle and I think I am going to win this one. Please tell me this isn't normal. I will open the ecu up tomorrow to determine exactly what went on inside. Perhaps some capacitors blew and leaked who knows what I'll find. I'll be sure to post some pictures.

The next step is to determine whether this can be fixed or just re-code another ecu. I also need to clean up the harness connectors since they got a bit messy.

Any suggestions?



Anyone know of a cheap place for used ecu's and re-coding?

Thomas, I'm not sure if you've made any progress, but I would really recommend checking out your ecu from the inside. Hopefully, this helps you and other that come across this thread.

To be continued...

[sirminder]

Here are some pictures of inside the ECU.






Nothing appears to be bad. Only two capacitors located inside and they are not blown or leaking. All other smt components appear to be OK.

The only bad part I found was on the bottom side of the board. It looks like the mystery fluid made its way down and affected some of the contacts. I will have to check each pin from the male connector to the bottom of the board one-by-one for continuity.



Is there any way coolant, power steering fluid, brake fluid, etc. could have gotten in? I know there is a chance water can get through the ecu compartment box. This stuff has about the same consistency of motor oil.

I will have a closer look and see if I can trace where this came from. Hopefully, electric contact cleaner will help in cleaning up the corrosion. I don't have the pin removal tool, so I'll hope for the best.

[sirminder]

Success!

Pin contacts # 86, 115 and 116 had some corrosion as shown in the pictures above. Once that was removed, I plugged the ECU in and did the reset procedure again. I let the throttle body do an adaptation on its own with the key in the ON position. The high pitch sound and clicking from the throttle body sounded a bit cleaner. Turned the engine on and let it idle for a good while. The only light that was on, was the traction control light. Once I went for a short drive, the light went away.

I am still not sure where that clear substance came from or what it is. There is some located underneath the relays in the ECU compartment, but I am sure it came from where the harness connects to the ECU. The ECU sits above the relays and there are a few drops of that substance directly below the harness connectors. The black cloth-like tape that is wrapped around the cables was a bit 'gooey'-like. I couldn't find a way to remove the outer back cover on the harness connector to have a closer look.

I haven't checked what codes are now present because I think the cable I have might be defective (cheap ebay cable). I'll wait a few days and see how it goes.

Feels good to drive my car again after nearly 2 months of this headache!

[sirminder]

Forgot to ask:

Anyone know what pin #s 86,115 and 116 do? And, how they could be related to the throttle body?

The diagrams posted by a4darkness show that J338 uses pins 83,84,91,92,117 & 118. However, those pins did not appear to have any corrosion on them.

Thanks!

[KHARDa4]

Forgot to ask:

Anyone know what pin #s 86,115 and 116 do? And, how they could be related to the throttle body?

The diagrams posted by a4darkness show that J338 uses pins 83,84,91,92,117 & 118. However, those pins did not appear to have any corrosion on them.

Thanks!

Necro bump. I am having similar issues. Can anyone identify pins 115 and 116 at the ECM connector?

Sent from my SM-G955U using Tapatalk

[a4darkness]

Old Guy to the rescue...

As I never posted the solution here... it was the female connector of the wiring that connects to the throttle body. Even after everything passed electrical tests it was some kind of breakdown in the connector itself. Found one at the junkyard, cut the old one off, grafted the new one on and all the problems went away. Case in point, the wiring and connector itself can test fine but still not work. Credit to a buddy at a shop who had the same weird issue on a newer S6. Turns out it's not an entirely uncommon issue.

[Mike Tries]

Old Guy to the rescue...


As I never posted the solution here... it was the female connector of the wiring that connects to the throttle body. Even after everything passed electrical tests it was some kind of breakdown in the connector itself. Found one at the junkyard, cut the old one off, grafted the new one on and all the problems went away. Case in point, the wiring and connector itself can test fine but still not work. Credit to a buddy at a shop who had the same weird issue on a newer S6. Turns out it's not an entirely uncommon issue.

Wow, thank you! I thank you and Old Guy (for originally posting this image?). Pins 117 and 118 there? Yeah. They fell out the back of my harness plug when I had it apart. But I wouldn't have known to look at them if it weren't for your post here. You saved the day!