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Billy
Billy, Trainer/ Master Technician
Category: Audi
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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Audi TT: 2002 Audi TT 1.8 liter 5 speed manual. Non Quattro.

Customer Question

2002 Audi TT 1.8 liter 5 speed manual. Non Quattro. Came out of the grocery store and it wouldn't turn over. No crank, just dead. Console says press clutch to start. Battery 12.35v. All fuses in tact. Disconnected both clutch safety switches. Tried jumpering each, no luck. What am I missing.
Submitted: 1 year ago.
Category: Audi
Expert:  Billy replied 1 year ago.
Hello and Welcome! I'm Billy and i will assist you with your inquiry. Feel free to ask if any further info is needed.
My apologies for the delay, thank you for your patience.
Did you try removing only the upper switch (as this should be the one for the starting)? and did you try removing its connector without jumpering it? (as some variants it cuts the line when the pedal is depressed)?
Customer: replied 1 year ago.
Tried that. Didn't work
Expert:  Billy replied 1 year ago.
ok. Do you have a led test or multimeter so we can do some checks?
Customer: replied 1 year ago.
Have a multimeter, checked resistance on both switches. They were good
Expert:  Billy replied 1 year ago.
Hello again,
Let's concentrate on the upper switch (as the one below it is used for the cruise control and should not affect the starting).
On the upper switch you have a connector. disconnect, and turn ignition on, put one lead of the multimeter on the first pin (connector side), and the other lead on to a known good ground. You should get 12V, with ignition on. Are you?
Expert:  Billy replied 1 year ago.
If you are having 12 volts, i would try supplying the engine control module, with positive 12 volts, on the pin 39. This should erase the message on dash. And you will be able to start the engine. And this would mean that the wiring between the switch and the engine control module is broken somewhere. The easiest way would be having a new wire from pin 2 on the switch, to pin 39 on the engine control module.
If you don't have 12 volts however, you would need to double check the fuses, (fuse number five), and its connection to pin 1 on the switch.
Kindly get back to me with your findings, or if further info is needed.
Regards,
Billy
Customer: replied 1 year ago.
I will check when I get jome
Expert:  Billy replied 1 year ago.
Take your time. Best of luck for now!
Customer: replied 1 year ago.
No 12v at the switch. Fuses are all ok.
Expert:  Billy replied 1 year ago.
No 12volts at both pins of the switch? (and fuses are good)?
Can you check or swap the fuel pump relay (behind the storage on driver's side (it is relay number 4 from left to right). As this switch is powered by the relay through the fuse number 5 and sends positive supply to pin 39 on the ECM, so the ECM confirms that the clutch pedal is depressed.
Customer: replied 1 year ago.
So I had a chance to do a little more testing. I not getting 12v at the 87f/diesel contact under the fuel pump relay. I don't have a spare relay to swap out and see if that is it. Should I test a certain contact within the relay? Should I jumper something to test it? At this point I have ordered a new clutch switch(even though I don't think that is the problem). I also replaced the ignition switch.
Expert:  Billy replied 1 year ago.
You can jumper from 30 to 87 or 87f (as that's what the relay does).
With relay removed.
Kindly get back to me with your findings..
Customer: replied 1 year ago.
Jumped 30 to 87 with the relay removed. I could hear the fuel pump start running, but still not cranking.
Expert:  Billy replied 1 year ago.
Did you check if getting positive 12 volts on the pin 39 of the ECM?
Customer: replied 1 year ago.
It just started raining, I will check it when it stops.
Expert:  Billy replied 1 year ago.
Take your time... Good luck!
Customer: replied 1 year ago.
Just had a chance to access the ecm. I have everything unplugged, but can't find s good schematic to find which is pin 39
Customer: replied 1 year ago.
Think I found pin 39. No 12v with key on.
Expert:  Billy replied 1 year ago.
Hello,
Is this the same wire (from color and gauge) from pin 2 on the clutch switch (upper switch)?
and can you get me the engine code (three letter code, so we confirm the variant, and confirm the problem)?
PS: you need to check with connector plugged on the ECM, back probe the pin 39, and the other end of the multimeter on to a good ground.
Customer: replied 1 year ago.
Ok, finally have a chance to work on it again. It looks like the wire colors are the same. I'm not sure where to find the engine code. The vin is trusc28n221005523
Expert:  Billy replied 1 year ago.
Hello,
The engine code would be stamped on the block. towards the pulleys. It should be a three letter code such as AWP. In fact that most likely is your engine.
Having the same wire (same color), you can double check (continuity check on that wire). And with the ECM connector on, you can supply 12V to this pin (at the back of the connector) and the ECM should get the clutch signal, and enable the engine to start.
If that is confirmed, all you need to do would be fixing that wire, or get a new wire from the pin2 at the switch to the ecm.
Kindly get back to me if further assistance is needed.
Regards,
Billy