AAN no fuel or spark???

[Alan]

Just checked fuel pump, working fine.
Going to remove ecu and check the cam sensor from there...

[Alan]

Whilst removing the ECU, I checked the fuses located just above it and the one on the right (yellow connector block) was blown.
I replaced the fuse and cranked the engine, and the fuse blew instantly.
Any ideas what this is connected to?

[S2central.net]

Sorry - will need a photo to work out what fuse you mean. There are some good pics on www.sjmautotechnik.com of the ECU and fuses for AAN. Try plugging in the fuse with the ECU disconnected to see if it blows. Then plug in ECU and check again... then turn ignition on and check one more time.

Either way it sounds like some frayed / shorting wires in the loom - could take some time to find.

[Alan]

Yes, a picture might help:
The fuse is 15 Amp so something fairly hefty is shorting.
Anything to do with the alternator?

[UrS4boy]

Yes, a picture might help:
The fuse is 15 Amp so something fairly hefty is shorting.
Anything to do with the alternator?

Nothing to do with the alternator except that with it blown, the engine won't start and therefore the alternator won't turn.

I am guessing tht you have some frayed coil wires on your coil pack that are shorting out to the cam cover, causing that fuse to blow. Remove the coil pack (the 20v Turbo plate), with all the coils intact. Look for broken insulation, especially where the wires enter the 20v Turbo plate at the fire wall end. Short term solution is to wrap them with electricians tape. Long term solution is to replace the wires and/or the coils. This is a fairly common AAN problem as the cars age so I presume it applies to the ABY and ADU as well.

Good luck.

[S2central.net]

- wot he said

[Alan]

I fitted the 1.8T coils about a year ago, and went through the wiring in case there was a short somewhere.
Possible as the fuse is not blowing now and the fuel pump is engaging.
I guess the cam sensor is OK if the pump is running.
Still no spark though...

[S2central.net]

Cam sensor is the gate to sparks.

RPM sensor is the gate to fuel... must be cranking over a minimum speed before ECU turns on fuel - handy in a big shunt - also handy to not be pishing in loads of fuel into an engine that has faulty sensors.

[audiman]

My suggestion would be to buy yourself or borrow, or even pay somebody else to code read the car.

You are spending hours of time for something that could possibly be diagnosed easily in about 10 mins.

[Alan]

According to one of the forums:
"The ECU controls the fuel pump (FP) relay (J17)(PN 4D0 951 253) (located under the driver's side (LHD) knee bolster, right end of relay panel). The ECU will not engage the J17 until it has a signal from the cam position sensor (G40) during start-up and then the engine speed sensor (G28) during running."

The problem I have with this is that the fuel pump is engaging during cranking.

I again scanned using VagCom and now I am getting a hall sender fault,
however. it IS pulsing to zero on the scope while cranking
I ordered the sender today as it so cheap (not!!), I may not need one at all.

Stumped.

[Alan]

Just changed the cam position sensor and still nothing
Fuel pump is coming on as before.
Vag com not detecting any fault on the cam sensor now but instead the G4 engine speed sensor is showing a fault!!!
Semtex now on the shopping list...

[pixsaudisex2]

HA HA HA
Just spent four hours plus on a vehicle like this and took a while to find the fuses under carpet blown as you say. and i can only say on this vehicle im hoping its a coil pack gone down. shorting it put although on me s2 i have had coil packs pack up and the most knakered wires you could imagine and it never popped no fuse.

[20vQC]

Maybe was better to test the sensors before!! Try to test the crank angle sensors before buying the new ones!!

[pixsaudisex2]

Well it was a coilpack on the one im looking at. changed it and all is good.