Help With Wiring Harness

[UrS4boy]

OK if you have power at S24 then I believe the fault must be downstream of the fuse board. You now need to check you have continuity between S24 and N71 pin 1, N75 pin 1 and N 80 pin 2. Then check continuity between N71 pin 2 and ECU pin 4, N75 pin 2 and ECU pin 33 and N80 pin 1 and ECU pin 5.

Agree. These photos are for the AAN harness and are intended to show the that pin numbering is imbedded in the connector. (Photos are from an AAN post that I did to document that it is possible with an AAN to physically cross-connect at least 2 of 4 two pin connectors at are on the intake manifold side of the engine: http://forums.quattroworld.com/s4s6/msgs/252056.phtml - not sure if this is possible with a 3B/ABY/ADU)

N71:


N80:

[bilko0795]

You spent £258 on an ISV?

Yep good old TPS and that was with 10% discount.

[bilko0795]

Also check the 2 pin connector for the N75 is not shorting out.

You should have continuity for all of the above connections [/QUOTE]

Alex

How do I check the two pin connection for the N75 is shorting out.

[Error404]

see if you have continuity between the two pins

[UrS4boy]

How do I check the two pin connection for the N75 is shorting out.

I don't know why it would be "shorting out". (But it might be). Normally, power to the N75 on an ABY comes from the S24 fuse that is energized by the J17 FP relay which in turn is energized by the ECU when it gets a good G28 engine speed signal (> 13 RPM). With the engine running, there should be 12V power in the N75 connector on the pin connected to the blue wire with the red stripe (Ground the other DMM probe to the cam cover). In operation, the ECU grounds the N75 through the ECU pin T55/33 via a green wire with a yellow stripe. Normally during a N75 voltage test at idle, probing both N75 connector pins with DMM probes (plus in the blue/red pin, negative in the green/yellow pin) should get you zero nada zilch Volts because the ECU won't have opened the path to ground. If you do get 12V in this two pin test, then your ECU is FUBAR'd.

[bilko0795]

see if you have continuity between the two pins

Nothing showing on the N75 pins also nothing with the engine running even tried a different ECU

[UrS4boy]

Nothing showing on the N75 pins also nothing with the engine running even tried a different ECU

BUT did you try the DMM set to 20 VDC with the (+) probe in the N75 pin with the blue/red wire and the (-) probe touching the cam cover, with the engine running? You should have 12V (well actually more like 13.7V)

[Error404]

Nothing showing on the N75 pins also nothing with the engine running even tried a different ECU

That's good.

What about between S24 and the N75, N71 & N80 pins as described above?

[bilko0795]

BUT did you try the DMM set to 20 VDC with the (+) probe in the N75 pin with the blue/red wire and the (-) probe touching the cam cover, with the engine running? You should have 12V (well actually more like 13.7V)

Yes showing no power to the pin I'm waiting for a sparky to come up not to confident he will turn up though didn't sound to confident on the phone after asking me some questions about the problem.

[bilko0795]

That's good.

What about between S24 and the N75, N71 & N80 pins as described above?

Alex
as said no power to the any of the pins I was getting 0.05v but now zilch can't reach the plugs to test with the pins on the ECU as you mentioned leads to short on the MM.