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Discussion Starter #1
Hello:

We are an auto electrical repair shop. We're working on a 2006 CTS 2.8L with console shift. The key won't come out and all or most all of the 17 modules are setting U1000 codes. The car runs fine and we can communicate with all the modules. Using a test light to look at the circuit for the Ignition Lock Cylinder Control Actuator shows that the Dash Integration Module is not providing ground. Using a Tech II to command the DIM to turn the Park Key Lock Switch on works. The Tech II doesn't have a data line that tells me whether the DIM knows if it's in park or not. Both Alldata and ProDemand don't have any additional help. The vehicle doesn't have a PRNDL indicator, just the letters beside the shifter with one light for all the letters. The TCM knows when we shift thru the gears. Questions: Is this vehicle like others where the TCM sends the tranny position to the ECM which then tells the DIM? If so, how can I tell if I have a bad TCM or ECM or DIM? Also, we've repaired over a hundred communication problems, but we've never seen one where every module sets the U1000 code with no other codes or additional diagnostic help. Any similar experiences out there?
 

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06 CTS Sport/Luxury package
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When I had my head on crash several years ago. It jumped the set screw that is attached to the shifter. You'll have to put the car in the air with someone inside to make adjustments.

Have then cycle through the gears and someone under it to set it correctly.

The set screw, nut actually, is located on the passenger side of the transmission.

When I had this issue, I was still able to push the shifter more forward to turn and remove the key. I only did that a few days until I could lift the car.

That could be one issue, but it looks like you've already tackled the electrical issues. The only other thing would be the ECM itself. But I personally haven't heard of this problem on an 06. And again, you've probed it out.

KOT
 

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The fix: Took an experienced guess and went to the PCM first. Cut the wire for Class 2 data bus and checked both ends with a test light. The end to the rest of the car had the typical morse code flashing, but the end to the PCM was dead. Plugged in new PCM and rechecked the wire. Now the PCM end of the data bus wire had regular "state of health" pulses. Programmed PCM fixed all problems and codes.

Complicated!

No good reference or diagnostic help out there?

Thanks all.
 
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