Anyone have the throttle body pin-out description?

**RPMtech147** · 12-05-2022 11:53 AM

Fighting an issue with TPS faults on a 2012 A4 CAEB Quattro.

All the wiring seems to have good continuity to the ECU but I need to know what I'm suppose to have on each wire. It looks like it may have lost the 5Vref.

I need to know what should be on pins 1, 2, 4, and 6.

**Smac770** · 12-05-2022 02:35 PM

If you have the workshop manual set, the Generic Scan Tool for CAEB one has testing process for the J338, pages 198-201.

6-pin plug:
ignition off, pin 3 to pin 5 on the J338 should measure 1.0-5.0 Ω. (this is testing the motor)
ignition on, pin 2 to pin 6 on the harness plug should measure at least 4.5 V.

It does not explain if pin 2 or pin 6 is the ground or the 5V, but that's easy enough to confirm. Pin 1 and 4 should vary as a fraction of 5V proportional to the amount the throttle plate is moved. Based on SSP 210 page 20, it appears G187 (pin 1) is an increasing voltage with increasing plate angle, and G188 (pin 4) is a decreasing voltage with increasing plate angle.

**RPMtech147** · 12-05-2022 05:35 PM

You're the man, Smac. I think we're looking at a faulty ECU. No 5v on 2 or 6 at the connector unplugged.

**RPMtech147** · 01-23-2023 09:20 AM

Just an update to this one because it kicked my ass.

All symptoms pointed to bad DME. DME replaced, no change. (luckily used so not a big loss). Load tested all wires associated to the throttle body (Take a car battery and hi wattage halogen bulb and load test each circuit) passed with flying colors. Replaced the TB connector and made an overlay to the DME/ECU anyway. No change. Swapped throttle bodies, same damn issues. I went around in circles for hours. Checking my pin-fit at the DME connector (which I did early on, but starting over because I'm out of ideas) I was getting questionable drag with my pin-test gauge.

The only thing left could be pin fit.

I pulled the DME harness apart and 1 by 1 on the wires in question, slightly crimped each female harness pin down ever so slightly until it had good solid drag on the DME pin. Reassembled, fixed. First time I've seen a pin fit issue at the DME connector.

**Smac770** · 01-23-2023 10:03 AM

Always someone wanting to be that special unique. :-D

That's curious that the pin had "come loose"? And didn't start out that way, developed over time. Congrats on finally discovering it.

**RPMtech147** · 01-23-2023 06:24 PM

Originally Posted by Smac770

Always someone wanting to be that special unique. :-D

That's curious that the pin had "come loose"? And didn't start out that way, developed over time. Congrats on finally discovering it.

from my understanding, the client has had the car for years, and this has been an issue on and off since they owned it. It would fault, they'd shut the car off, then back on, and it would drive fine. it would be OK for a few weeks, rinse repeat. They had it at two other shops over the last 6 months once it had a hard fault, EPC/check engine light, and no throttle.