ECM replaced, now instrument cluster not working, misfires and tries to stall

Good morning.

did the dash respond with the old PCM?

Did you have the replacement flashed to your car?

New or used PCM?

Are there any codes stored?

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Roy

Okay, the PCM does provide power to the relay, You need to test for power at the relay in the start position.

I attached a diagram for you.

Roy

With the misfires, it will lose power. You need to check the items I listed.

Was the dash working before the PCM replacement?

Roy

Okay, that is pointing to the PCM.

Where did you get the PCM?

Roy

That's no good. That's the issue. You need a rebuilt or new one especially since you had it programmed.

Roy

Okay, rock auto is the best deal. You will have to have it programmed to your car.

Roy

Yes, no core.

Roy

You are welcome.

Always glad to help.

Roy

OK, What does not function in the system?

Did you get everything else fixed yet?

Roy

Diagnostic Aids

* A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code.
* Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
* Communication may be available between the BCM and the scan tool with either the low or high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the low and high speed GMLAN systems.
* Use Data Link References (See: Information Bus > Initial Inspection and Diagnostic Overview > Data Link References) to determine if the module uses high or low speed GMLAN serial data communications.
* Some control modules may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the control module.
* This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to, providing the vehicle is equipped with the control module.