AAN wiring or sensor problem, 8 fault codes!!!

[Sleeper_Avant]

my A4/(2.2 20vt AAN URS4 engine) has always been a bit sluggish low down the revs and if ticking over for a while, like 5 mins ish seems a bit choked up like its over fueling a bit, never bothered me and is fine on full chat/WOT.

ive been playing with my new toy, Bosch KTS670 and decided to pin out the obd plugs and have a look at the live readings and any fault codes etc.

i was a bit shocked!

8 fault codes!!

but some of the live readings were also very very odd,

engine coolant temp is 68degrees c from cold right upto 98degrees when my fans actuate.

inlet temperature 39degrees c again from cold right to 98degrees

throttle position is 105.7degrees and doesnt move at all

Codes:
020B air temp sensor open circuit/positive short
020A engine coolant temp sensor open circuit/positive short
0206 throttle valve position faulty
04EE N75 valve short to earth
0206 battery voltage too low
0210 altitude sensor too low
0203 cylnder identification faulty
021c knock sensor 2 no signal
0119 vehicle speed sensor no signal

I was thinking wiring, but to be fair i dont know as this was done by a "mate" for me while i built a motor for his cosworth as a favour,

im just starting to look up posibilities and wiring diagrams i have on my bosch for common wiring earths, 5v lives and fuses etc.

i havent yet checked power at the various sensors as ive ran out of time today but will do so tomorow after work.

Cheers, Sean.

any of you clued up lads got an incling?

dont fancy pulling the harness out and re-wiring it but if needs must............

[UrS4boy]

AAN ECU T55 Pin-out with hyperlinks to devices

Lots of issues. Ignore the engine speed code (always comes up when codes are pulled with the engine off). Could be a G62 engine coolant sensor.

Info on all the inputs to the AAN ECU here (click on the labels)

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

AAN ECU pin-outs with hyperlinks to devices:

http://forums.quattroworld.com/s4s6/msgs/21009.phtml

[Sleeper_Avant]

Cheers bud, looked for these but couldnt find em :cheers:

[Sleeper_Avant]

i also dont run a MFTS so wiring isnt plugged in to anything, is this an issue maby?

i know on AAN it shouldnt cause any running probs IIRC?

Ta.

[UrS4boy]

i also dont run a MFTS so wiring isnt plugged in to anything, is this an issue maby? i know on AAN it shouldnt cause any running probs IIRC? Ta.

Click on the G62 and MFTS labels in the Engine Bay Device Map to confirm your thoughts.

[johne]

The MFTS doesn't feed the ECU, there's a seperate temperature sensor at the back of the block for that which it looks as it needs replacing.

John

[Sleeper_Avant]

yep, as thaught :cheers:

early finish for me tomorow then out with the `scope and `meter D:

Sean

[Sleeper_Avant]

Right, gathered all the intel i need, tidy up some wiring and *HOPING* theres a problem with pin 30 wiring as this is the earth for most of the sensors mentioned above........

wish me luck, will post back

[Sleeper_Avant]

Right, pin 30 should be ground but it is dead, this is the common ground for the sensors that are showing faults,

does the ECU give or take the ground feed along with the sensors?

[Sleeper_Avant]

Which plug is the T6 in bottom right corner of the above diagram?

this may have been lobbed off and this could be the problem,

i do have 5 or 6 different colour multiplugs

just asking before i slash the harness ipen again lol

[UrS4boy]

Which plug is the T6 in bottom right corner of the above diagram? this may have been lobbed off and this could be the problem.

Since you started the thread, I have redone the Motronic Diagram in my Motronic pinout post to make some corrections and additions (e.g. the original lacked info about all 4 fuses above the ECU) . The T6m connector you ask about is for the trip computer coding card. Shouldn't be an issue for you in my opinion. However, you are right about Pin 30/T55 being the common denominator for your issues. The ECU takes those signals TO ground via Pin 30 (probably out Pin 19/T55).

Revised AAN ECU pinout: http://forums.quattroworld.com/s4s6/msgs/21009.phtml

[Sleeper_Avant]

Right its fixed, ive put a ground wire from the body to Pin 30, green/black wire feed comes from the black plug here (i havent used this)


all readings are now live and as they should be, and not 105degrees throttle position!

before............



after!



The mess i created after removing the protective tape and conduit then begin ripping the harness out





its also fixed my hot starting problem

Thanks for your help Dave, top man.

[Sleeper_Avant]

the car feels slower, and theres no flames or bangs when changing gear after a thrashing

but drives so timid and placid now, maby get the fuel economy back

[UrS4boy]

You're welcome. Glad that I could help. I am surprised that you aren't getting better performance now that the ECU is getting the G61 knock sensor signal (without it, it would have dialed everything back). If you haven't already, kill the power to the ECU for 10 minutes, e.g. the power that goes into the ECU at Pin 18 (normally the red fuse holder above the AAN ECU - but where you have that, I am not sure). That will reset the ECU back to OE settings, and clear any codes. It might still be working off the adaptive maps that it created for itself with the G61 knock sensor out of commission (or so it thought).

[Sleeper_Avant]

it was lethargic off boost, as if it was over fueling but WOT was like a scolded cat.

just a quick drive today and i think its got 2 month old crap fuel in it, will throw some 99 octane in tomorow and give it a thrashing

Cheers again Dave.