2005 Silverado, did a 4.3L to a 6.0L -- swapped over all wiring and PCM from the 6.0L

Everything runs perfectly fine, the only code it is giving is P0650 which is a malfunction indicator light code. I removed that code from the tune, to see if it would make the light turn off, but the check engine light is still illuminated.

So, thinking it was a problem with the PCM, I went and cut the brown/white wire at pin 46 at the PCM - in theory (I think) this should have turned off the check engine light on the dash, but the dash light stayed illuminated!

I also hooked up a volt meter to the PCM side of pin 46, and the PCM is providing a ground, as if the PCM wants the checking light to be on even though there are no codes present.

Has anyone seen this? It is almost like there are two issues - a ground somewhere on the truck side causing the light to stay on and then an issue with the PCM that is grounding pin 46 when it shouldn't.

Though - Maybe if the truck isn't getting a resistance (or something) from PIN 46 of the PCM it automatically sets off the engine light?????????

Any guidance would be a big help.

 

Also, I forced the check engine light OFF using HP Tuners scanning software, the PCM still provided a ground to illuminate the check engine light (verified using the volt meter)

 

I wonder if there is an issue with the calibration you're using being corrupt? or possible the PCM is the issue?

 

Sounds like the driver for the cel is grounded permanently in the pcm..was it doing it before the swap, if not try the 4.8 pcm and see what it does

 

This is what I'm thinking also, but do you know why the check engine light would be on even when the signal wire is cut from the pcm?

 

Probably another way around that through instrument panel or something, would need to look into that..... I would swap pcms and see if it fixes it..... What year truck and what year engine???

 

2005 truck, 2004 engine/PCM

I'll prob tune the original PCM that came with the truck instead of the PCM that came w/ the engine -- plug that in and see what the light does, then move onto the instrument panel and bypass whatever is between the panel and the PCM (run wire straight to PCM)

 

Do you have a scanner than shows ipc codes, its possibly you have a vin mismatch or sonething that could throw an engine light

 

Could a vin mismatch cause this? The VIN in the PCM definitely does not match the truck. I disabled VATS to allow the truck to start

I've never heard of IPC codes, I have hptuners scanner and a normal OBD 2 reader, I don't think either read IPC

 

I do not know if it was doing this before the swap - as the engine/pcm was bought out of the vehicle.

The original PCM is from the V6 4.3L. If I hook that up, but do not start the engine - will I damage anything? I would just turn the key to "on" and see if HP Tuners scanner can toggle on/off the check engine light