There are 4 wires. Look in the swap faq for details on how to track down the correct wires needed (see sig).
I have just recently transplanted an AEB from a '99 into my 1987 Audi 4kq. I'm using the factory harness and ecu from the A4 and I've got everything to work with the 4k cluster except a working check engine light. Has anyone here with an AEB swap managed to figure out a way to have a functioning MIL lamp?
Thanks, I'll look again. Your site has been helpful through this build. I have a working diagnostics port but I've been looking for one wire to run to a bulb for a check engine light. I've tried two wires that run from the ecu to the cluster. One is the "Trailer Operation Indicator Light" the other is a black and purple wire that has no obvious task. None of my wiring diagrams have a check engine light called out in them. I also tried tapping into the green (K-diagnostics) wire at the diagnostics port to see if I could get a signal that would operate a check engine light with no luck. I have not tried the white and black wire (ecu pin 43/ diag. port 13. I did not see any other possibilities in the various wiring diagrams. I hope I'm on the right track. If you or anyone else can add anything that I might of missed let me know.
Sorry to drag up such an old thread, but I'm pulling my hair out trying to find the correct wires for the cel/mil for my '98 AEB swap and it's making me feel like an idiot. I have been through every thread that could find, every FAQ that I could find and all through the Bentley and I still haven't come up with an answer. If anyone can help, I would really appreciate it.
Okay, so I looked all through the Bentley wiring schematics looking for the 1998 AEB MIL lamp wiring, and this what I have found:
The 1997 schematic shows the MIL (K83) wiring coming from pin #17 on ECM. This wire is a ground wire to activate the MIL lamp.
The 1998 AEB schematic shows ECM Pin #17 as the Trailer Operation Indicator Light (K18) which appears to be a power wire to activate the lamp (obviously this has nothing to do with the 1998 MIL, but I simply made the connection to show that the 1997 ECM wiring appears to be very different than the 1998/early 1999 wiring).
I could not find a MIL (K83) wire in the 1998 schematic. The early 1999 schematic is the same as the 1998.
The late 1999 schematic has K149 lamp labeled a "Warning Light for Motor Electronic" (I don't know what that is exactly). However, this wiring track goes nowhere. I does connect to connector T32/13, but that's as far as the information leads. Pin #17 on the ECM for this schematic also goes to the Trailer Operation Indicator Light (K18), so it appears similar to the 1998 wiring.
For 2000, the schematic shows the MIL (K83) lamp as ground activated from ECM pin #47. This appears to be a similar layout as the late 1999 described above, but the connector T32/13 is shown to connect up to the "Fault Light for Power Accelerator Activation". The MIL (K83) lamp is shown to be connected via T32a/14, which is the Fault Light for Power Accelerator Activation lamp connection in 1999. (pin #17, which is used for the Trailer Operation Indicator Light mentioned above, does not appear to be in use with the 2000 wiring, indication that the 2000 wiring is very different than the others).
(Just to be clear, I only mention the ECM Pin#17 and the Trailer Operation Indicator Light as a comparison between the 1997 ECM wiring (which shows ECM pin #17 as the MIL K83) and the other years)
So what happened in 1998 and 1999? Does the ECM in those years follow the 1997 (it appears not, but...) or 2000 format or neither? I'm really at a loss here, so if anyone can help, I would REALLY appreciate it.
For anyone who may be watching this or who happens to look up this information in the future, the answer is that Pin #17 (green/brown wire) from the ECU is what triggers the CEL. If you trace this wire through the Bentley, it shows to connect in the instrument cluster at connector T32/16 (32 pin green connector) which is labeled as K18 (Trailer Operation Indicator Light).
good info, i didn't always have codes, i would do this, but such is having a MKI BT20v wideband swap.
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