P0650 code 2006 Silverado 4.8 manual to 4l80e swap COS3

[megadeus]

Before I go down the rabbit hole chasing this code.

Is P0650 a code set by running a COS3 setup?

I have always had the code set since I had the truck but I need to start setting up my truck to pass emissions shortly. ( I have that effort on lock but this code CEL light operation is unrelated to emissions equipment.)

I understand the PCM grounds pin 46 on C2 to control the light. So far the symptom is pointing to a wiring fault.

The CEL doesn't turn on when I turn the key on engine off, BUT it does turn on once I start the engine and stays on constant as long as the engine is running. WTF over.

I cannot command the CEL on/off with the FS2 or any other scanner. Is there an EFIlive COS default I am missing?

[Chevy366]

First thing to check is whether the bulb comes on when it's supposed to. It's supposed to come on for a few seconds when the ignition is turned on. If the light turns on for a few seconds and then goes off, you know the bulb/LED is good. If the lamp turns on and stays on you also know the bulb/LED is good. If the MIL does not come on at all, you need to diagnose where the problem lies. If you have access to an advanced scan tool, you can use it to command the MIL on and off. Verify operation that way. Physically check if the bulb is burned out. Replace if it is. Also, inspect to make sure the bulb is seated properly and making a good electrical connection. Visually inspect all the wiring & connectors leading from the M.I. lamp to the PCM. Inspect the wires for chafed insulation, etc. Separate all connectors as required to inspect for bent pins, corrosion, broken terminals, etc. Clean or repair as required. You will need access to a vehicle specific repair manual to identify the correct wires and harnesses. Check if other things in the instrument cluster are working properly. Other warning lamps, gauges, etc. Note that you may need to remove the cluster during the diagnostic steps. If your vehicle is equipped with a PCM or MIL fuse, check it, replace as necessary. If everything thus far checks out, you should use a digital volt ohm meter (DVOM) to probe the appropriate wires in the circuit at the lamp end and the PCM end, verify proper operation. Check for shorts to ground, or an open circuit. If everything checks out against manufacturers specifications, replace the PCM, it could be an internal fault. Replacing the PCM is the last resort and requires the use of specialized equipment to program it, consult a qualified technician to assist.

Yep, sounds like a shorted wire.

[megadeus]

I'm hardcore good on the wiring diag side of things. I just want to make sure that there is not a parameter of normally running a COS that will set this condition.

After that basic diag has been run through, I will probably end up overlaying a new wire from the PCM to the IPC pin to pin to eliminate the short. I really want to make sure the grounding switch in the PCM is not FUBAR'ed.

[joecar]

There's nothing in the COS to affect the basic functioning of the MIL.

[Chevy366]

In the COS when you disable the MAF sensor for speed density it will do a MIL (MAF failed) but in the COS set up it explains how to remove the MIL lamp illumination, other than that a COS should not cause a MIL light malfunction or illumination as joecar said.

[Taz]

...The CEL doesn't turn on when I turn the key on engine off, BUT it does turn on once I start the engine and stays on constant as long as the engine is running. WTF over.

I cannot command the CEL on/off with the FS2 or any other scanner. Is there an EFIlive COS default I am missing? ...

The CEL not coming on when you initially turn the key on, with the engine off, followed by the CEL staying on constantly after the engine is running - is a condition documented in the GM Service Manual.

First confirm continuity of the wiring between the PCM and the IPC (Instrument Panel Cluster). Then recheck this wiring for a short to ground, or short to 12 volts.

If these tests check out correctly, then it is either a defective PCM or a defective IPC.

I would recommend accessing a quality service manual for support if you are going to try and diagnose this yourself, or perhaps taking the vehicle to your local GM dealer just for an assessment / diagnostic of the at fault component.


Best regards,
Taz

[megadeus]

Thank you for the concise and intelligent responses. My wiring was damaged/shorted under the dash.