No start after pulling engine for timing chain replacement?

2008 GMC ACADIA

183,000 MILES • 3.6L • AUTOMATIC

CKRAMLICH

MEMBER
1 POST

I recently purchased this car as a mechanic special due to a loose timing chain causing the cams to go out of time. After pulling the engine and doing the timing chain job (triple checking the engine was properly in time) I reinstalled everything and when it came time to turn the key, no crank at all. All other electronics are working properly, battery tested good and is charged, all grounds secured properly, and I replaced the starter. The only thing I'm getting is the PWR/TRN relay clicking rapidly with the ignition in the on position, and clicking faster and louder in the start position. I'm assuming the PCM somehow got fried but I'm curious if there's anything simpler I could check or try before attempting to program a new ECU/PCM to the car

Apr 27, 2026 at 4:37 PM

JACOBANDNICKOLAS

✓Experienced Mechanic
110,236 POSTS

Hi:

Have you tried replacing the relay? Unless there was a problem prior to the chain, the PCM should be fine.

As far as the no-start, have you checked to see if there is power going to the starter trigger wire? It will be the smaller wire and purple in color. It should get 12v from the relay only when the key is in the start position. Let me know if you checked that as well.

I attached the wiring schematic below for you. I don't know if you need it, but I thought it may be helpful if you don't.

Let me know.

Joe

See pics below. Note: I had to cut the pic in half to make it readable. I did overlap the two so you can follow.

Images (Click to enlarge)

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Aug 6, 2026 at 7:54 PM

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