Audi S8 32V (AHC) Engine Wiring Diagrams

[Nollywood]

Hello guys!

Just wondered if anyone here can help.

I'm after a wiring diagram, for the Audi S8 32V (AHC). I just need the engine management / engine bay diagrams, and possibly the fusebox wiring (it may well be on the same sheets as the engine management).

Also, for those with 32V S8, does the 32V motor have engine speed sender, crank position sensor, or both? This is a 1998 S8.

I'm quite happy to pay for the diagrams, can be either by post or email. nollywood1966@hotmail.co.uk

Thanks in advance.

[ainarssems]

I suggest you get a copy of ElsaWin. Most of the wiring diagrams are in there but they are very fragmented. There is not like single engine wiring diagram with everything on it. If you need something specific I can try to find it and export to pdf.

I believe it has crank position sender and the same signal is used also to determine speed.

Are you going to run stock ECU or aftermarket solution?

[Nollywood]

Thanks CTL, you're a legend.

Does any 32V user know if the 32V motor employs an engine speed sender, crankshaft position sensor or both?

Engine was delivered Tuesday night, on the engine harness I've found a three-pin grey connector (D-shaped for late PF) which is obviously the crank position sensor. Then there's a fairly long black cable / coaxial terminating in a two-pin black connector. Wiring diagram suggests engine speed sender.

I know the CPS sits in a hole on the transmission bellhousing, and reads the 60-2 trigger on the flywheel. Engine speed sender would suggest it reads the 135 flywheel teeth (ring gear). I'm just not sure where it sits.

Any help here would be much appreciated.

[Nollywood]

Originally Posted by ainarssems

I suggest you get a copy of ElsaWin. Most of the wiring diagrams are in there but they are very fragmented. There is not like single engine wiring diagram with everything on it. If you need something specific I can try to find it and export to pdf.

I believe it has crank position sender and the same signal is used also to determine speed.

Are you going to run stock ECU or aftermarket solution?

I've got the diagrams, thanks.

From the engine harness, it looks like there were two sensors - the familiar three-pin grey one, as well as a two-pin black. The two-pin black connector has one heck of a long cable too, unless it was somewhere further back on the trans?

The grey one is in the usual location on the harness, on the left of the harness, where the crank sensor would normally be. Are you suggesting this sensor is positioned in a manner it can read the 60-2 trigger, as well as the 135 teeth on the flywheel? If that's the case, I have no idea what the long cable terminating in a two-pin black plug is.

I'm running the stock Bosch Motronic ECU.

[ainarssems]

I think there is only one sensor the grey one and it only reads position but ECU calculates speed from the same signal just uses different algorithm.

The black plug on long cable could be vehicle speed sensor from transmission output.

I will have a look through ETKA and ElsaWin to see if I can find out more.

Have you found out if you can pair A4 immobiliser to ECU or are you changing ECU software so that it does not need immobiliser? The thing with these old ECU's is that they cannot be flashed through OBD, not sure if it can be done on bench but I think you need to de-solder memory chip and use external reader/programmer for removal of immobiliser/mapping.

[Nollywood]

Originally Posted by ainarssems

I think there is only one sensor the grey one and it only reads position but ECU calculates speed from the same signal just uses different algorithm.

The black plug on long cable could be vehicle speed sensor from transmission output.

I will have a look through ETKA and ElsaWin to see if I can find out more.

Have you found out if you can pair A4 immobiliser to ECU or are you changing ECU software so that it does not need immobiliser? The thing with these old ECU's is that they cannot be flashed through OBD, not sure if it can be done on bench but I think you need to de-solder memory chip and use external reader/programmer for removal of immobiliser/mapping.

Thanks bud. The long black cable is indeed the VSS from transmission output, on the driver's side (not to be confused with VSS for road speed).

I've got the original transpondered key, the ECU and the little immobiliser interface box under the steering column, so no issues there. Otherwise I'd have to remove the immo chip (8-pin) from the A4 ECU and substitute the S8's chip.

So all looking good.

[ainarssems]

Looking through ETKA there are both engine speed sensor and ignition time sensor listed for older V6 12V engines(AAH and AEJ). Newer 30V V6 have only 1 listed as impulse sender and all 32V V8 engines only have one called either impulse sender or inductive sensor depending on chassis number.

ElsaWin only mentions G28 engine speed sensor for 32V V8.

I am quite sure that with unplugged camshaft position sensor car does not start but if you unplug it when engine is already running it keeps running. This would suggest that there is crank position sensor otherwise it would not know ignition timing. I will check on car tomorrow maybe I am mistaking with another engine/car.

[ainarssems]

I can confirm that pulling plug from camshaft position sensor while engine working does not stop it.

To me this means that there is other way of determining position for ignition and because there is no separate engine speed and crank position sensors then the same sensor must be used for both position and speed.

[Nollywood]

Originally Posted by ainarssems

I can confirm that pulling plug from camshaft position sensor while engine working does not stop it.

To me this means that there is other way of determining position for ignition and because there is no separate engine speed and crank position sensors then the same sensor must be used for both position and speed.

Brilliant! Thanks for checking things out for me. Will be getting to work on this project pretty soon.