Audi S5- No Crank ?

Bill Owner/Technician Jackson, Michigan Posted   Latest   Edited  
2009 Audi S5 4.2L 6-spd
No Crank / No Start

Vehicle towed in for no start condition. No related faults stored scanned with ODIS. I have been able to confirm clutch switch input, start button signal, Authentication key status changes to yes when the fob is inserted into the hole. I find the ECM is not grounding the starter relays but why? If I jump B+ to starter relay terminal the vehicle will start. What am I missing or what else is the ECM looking for to allow starting? 

Chad Technician
Winter park, Florida
Chad Default

I don’t have a diagram. So broken wire? Maybe it is grounding but it’s just not reaching

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Julio Owner/Technician
Laurel, Maryland
Julio Default

Any fault codes present when the full vehicle scan was done?

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Michael Mobile Technician
Clinton, Utah
Michael Default

Were you able to remove the relay and check all the contacts? It looks like there is a 5 Amp fuse (fuse 3) in the left plenum E-Box. (Whatever they mean by that) If it were burned it would prevent the vehicle from starting.

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Sisco Owner/Technician
Mendon, Vermont
Sisco Default

Sealed box where the DME is located-underneath the cowl panel between engine compartment and glass, by wipers (just was there on a Q5, same gig, kinda). Pull panel cover, remove fill for washer fluid and a few screws.

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Bill Owner/Technician
Jackson, Michigan
Bill Default

Yes the 5 amp fuse is good - I have pinned out both start relays ( in the Ebox) just missing the control signal from the ECM. No water intrusion inside the box either. I will look to further test the clutch switch today per Roberts advise - reading data with ODIS the switch input appears correct? Thanks !

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Nicholas Diagnostician
Brooklyn, New York
Nicholas Default

Hi, the only think I am not understanding is you said you are not getting ground at the relays but when you jump B+ to starter relay it starts. Have you checked all the wiring at the relays? Or are you just jumping the wiring at the starter? If you provide a ground to both relays does it start? The reason I ask is the last time I had a no crank on a Audi the ebox was full of water and I was able

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Robert Owner/Technician
Scunthorpe, United Kingdom
Robert Default

I had a S/S Tiguan in around 3 years ago just before I got ODIS, this one was intermittent non start, no FC's with Autologic, clutch switch is a full travel hall sensor reads in binary in live data (which it was changing status) Similar issue though to yours when non start the PCM wasn't grounding one of the start relays, I couldn't be sure on cause so trader uplifted it and sent it to the main

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Bill Owner/Technician
Jackson, Michigan
Bill Update

The clutch switch on this vehicle is actually 2 switches in 1... Clutch switch / Interlock Switch = G476 it is located under the brake booster on the clutch master cylinder (NOT the pedal) - Looking at scan data yesterday i made a mistake i was assuming the interlock pid was for auto trans and clutch switch was for manual - so when i press the clutch pedal and seen clutch switch status changing

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