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Won't Start

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'05 Turbo S Cabriolet won't engage starter. Bump starts fine.

Checked battery voltage and attempted to jumper cable start. Drove for 2 hours with voltmeter showing 13.5-14 volts to charge battery.

Still wouldn't engage starter once shutdown.

Checked Clutch Interlock for continuity when limit switch engaged - OK.

Pulled ignition switch - Audi Part # 4B0 905 849 - and checked terminal contiuity when turned to start detent - can't remember which terminals but got continuity between one of the center posts and an outside terminal. Anyone have the Terminal Pinout?

I suspect Theft Control Unit but don't want to surrender to dealer just yet.

How can I isolate Theft Control Unit as culprit?

BTW - Don't know if it is related but have intemittent Failure of Oil Pressure Indicator without Red Oil Pressure light comming on - suspect damaged lead grounding to Indicator Pressure Sensor.



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  • Admin

Since you have a Cab is there any chance the alarm/central locking unit under the drivers seat got wet? Have you felt the carpet for moisture?

Chances are you could save a lot of time igf you can find someone with the Durametric software, a PST2 or PIWIS tester and have them run a diagnostic.

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  • Admin

If you can jump start the car then the alarm/drive is not likely the problem.

If the car continues to run (even if you wiggle the ignition switch) then you can likely rule it out too.

Now you are down to a bad battery, clutch microswitch, and bad ground /wiring connections at and near the starter.

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Car can be "bump" started in 2nd gear down my driveway.

Will not start using starter, even with jumper cables from another car.

Durametric "Actual values" shows "Clutch switch" cycle open and closed with movement of clutch pedal.

Wiggling Key does not cause engine to die.

I'm willing to get new battery but find it unlikely to be the cause if starter won't engage with jumper cables attached.

I'll check the leads to the starter, ground and +12v.


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"Actual Values" "Immobilizer" shows "Closed" once running by bump starting

Shows "Open" after shutting off engine and won't go back to "Closed" by turning the key.

Have I just isolated the "Theft Control Unit" as failed?

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  • 2 weeks later...


After leaving the car sit for several days, I went out and it fired up immediately. After leaving it running for a couple minutes I shut it down and attempted to restart with the same symptom of not cranking.

I then checked the starter motor/solenoid cables and found that measuring voltage at the Starter Trigger terminal on the soleniod reads +12V when placing the key in the start position without the solenoid cycling.

Do I have a bad solenoid?

Can I buy just the solenoid? Item 10 in parts picture vice 11 for the starter/solenoid assembly.

Thanks Steve

Edited by invicto
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