Audi Q5 3.2 No Start / No Crank

Michael Owner/Technician Quebec Posted   Latest  
Resolved
Electrical
2010 Audi Q5 3.2L (CALB) 6-spd (0B6) — WA1LKCFP3AA015224
No Crank / No Start

Hi Guys,

I have a 2010 Q5 3.2l at the shop that came in with a no crank not start situation. i have no power going to my starter on my command wire. at the relays i have all my powers and 1 good ground going to starter relay 1 but my starter relay 2 is not getting its ground from the pcm on blk/green wire pin 22. if i ground that wire wile cranking it fires right up no problem. Now my issue is do i have something wrong with my pcm or is it seeing something it doesn't like and purposely not starting... i was able to retrieve these codes when i scanned it... wondering if anybody has any insight on this or maybe has seen this before?

Thanks 

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Mark Diagnostician
California
Mark Default
 

Looks like to you need to check for shorts to ground, shorts to power, or open on the starter relay control wire. Maybe try operating the relay from the PCM connector. The codes indicate an issue on the circuit, but probably an issue with the PCM driver in my experience.

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Steve Instructor
California
Steve Default
   

It is possible the load reduction relay is not working. Best to replace them both if one proves to be defective

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Brian Technician
Pennsylvania
Brian Default
 

Maybe just run an overlay,, from the relay to pcm.

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Nicholas Diagnostician
New York
Nicholas Default
   

It doesn't make sense that the ECU would ground starter relay 1 If there was a reason to block starter operation. Based on that if all the wiring is good, I would think the problem would be in the ECU. What happens if you ground it at pin #8 at the ECU? I would also test all of the grounds going into the ECU.

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Helpful
Michael Owner/Technician
Quebec
Michael Default
 

Yea I think your probably right

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Gerald Owner/Technician
Missouri
Gerald Default
 

Is this starter actually activated by a 5A fuse, or am I looking at these wiring diagrams wrong. Or is this a totally different type solenoid on the starter? Couldnt imagine 5A being enough current to power the solenoid without burning up and couldnt imagine the pcm actually helping to power it. Would imagine the pcm is just watching the circuit for cranking operation

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Chris Diagnostician
New York
Chris Default
 

The codes are telling the story here. "return message short to ground or open circuit" You nee to check the return wire, marked here The computer thinks it is seeing open circuit or short to ground, so you are looking for 0v or something like that. You should be seeing 12v while cranking. Now here is the rub: The ECM uses this circuit to confirm starter operation and also check for ground…

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Agree
Michael Owner/Technician
Quebec
Michael Resolution
 

hey so just a little update. triple checked all my data and looks like the computer was seeing all it needs to start. took the PCM to a local module repair guy and he said he traced the wiring back to a transistor in the computer that he saw nothing wrong with but for 100 he would change it so i said go ahead. He replaced it and i plugged it back in and started first shot. I then replaced both…

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