mnewbolds

UPDATE--- Just had the car scanned again at a shop that deals alot with audi's and vw's. While idling, the ecm voltage showed 0.00v.
ECT=-74F
Speed sensor= 85mph
Engine speed= 100/min
The tech there said it can cause the no drive issue. Any good sources for these ecm's or any good tips on what to look for and where? Thanks again

Rusty Spokes

I think if the ECM voltage is zero..then the power supply to the ECM on pin 26 is corroded or broken. The ECM should have constant 12v power there..even with the key removed. It is a red wire that comes off the 12v junction block under the dash on the driver's side. It is battery 12v all the time. (30)

I don't think you have a bad ECM..it just is not getting reliable power 12v.

My two cents worth.

mnewbolds

Ok. So what I am looking at is the gold box under the passenger floor. I have 5 separate plugs going to the module marked E,A,B,C,D. A,B,C have 24 pins each and E,D have 13 each. Also where under the driver dash is the junction you referred to? Thanks

Rusty Spokes

The ECM that is easy (sort of) to get to under the passenger side floor-board..the big one..is the engine control unit..there is another behind it and above..smaller..harder to get to. I'm pretty sure that is the ECM for the transmission..

If you take off the trim panel above the driver's feet..there is a relay box and lots of wires. Look and see a junction block with several connections. There is a 12v (30) block there that feeds several items..including the transmission.

I will check the part numbers for the ECM to be sure.

Rusty Spokes

See if your part number is 4A0927156AL..that is the transmission control ECU for most A6 quattros. On the Bay..about $70..if yours is defective.

Rusty Spokes

And check pins #50 #55..black wire on the transmission ECU..it should be 12v with the ignition key on.

See page 4 on the link:

http://12v.org/urs/1997_Audi_A6_Syst...g_Diagrams.pdf

mnewbolds

Checked #50 and #55. It will spike to @11v then immediately drop off to 0. Same with the red wire going to the engine control module. Hmmmm....

mnewbolds

Ok. So I followed the diagram to the servotronic relay under the hood and the relay was hot to the touch. Just from sitting with the key in the on position. Normal? Maybe relay Is stuck?

Rusty Spokes

You checking the pins on the transmission ECU?...and the constant 12v on pin #26 and switched 12v power on #50 and #55? Voltage drops off on pins #50 and #55 to zero?

If so..your ignition switch may be defective..very common problem and an easier repair to do. But grounds can fool you.

Pin#26 should be powered up 12v all the time..the 12v comes straight from the battery..look for the connection block under the drivers side kick panel..there is a block of connectors there..see if you have 12v constant on the terminal marked 30 with a paper label..Check your battery ground cable and replace it if any doubts..you should always have 12v at pin #26. That problem should be easier to find.

Check your ignition switch..battery connections..and grounds.

Rusty Spokes

Looking at the wiring diagram..there is no relay for pins #26, #50 or #55...they should power 12v (#26) or be powered up..not saying you don't have a bad relay..but the voltage drop is not on a relay.