Driving without wiring harness/transmission solenoid

Acej24 said:

Couple of weeks ago got a check engine light regarding the transmission. Took it to my mechanic and they said the solenoid and wiring harness need to be replaced. Solenoid was available but unfortunately the wiring harness is backordered with no timeline. Multiple dealerships told me the same thing that basically they order the part and GM puts out a search for it to see when it will arrive. Mechanic said ca

Acej24 said:

Couple of weeks ago got a check engine light regarding the transmission. Took it to my mechanic and they said the solenoid and wiring harness need to be replaced. Solenoid was available but unfortunately the wiring harness is backordered with no timeline. Multiple dealerships told me the same thing that basically they order the part and GM puts out a search for it to see when it will arrive. Mechanic said car can be driven but the light will stay on. Of course I’m not feeling too confident of driving in ICE mode so I’ve tried to keep the car charged as it seems perfectly find in EV mode. The past week though even though the battery is fully charged the engine will start and sometimes after a few minutes will turn off and go back to EV mode. When this step takes too long I’ll try to drive the car but the propulsion doesn’t seem right. I couldn’t even reverse the car up a minor driveway slope when the engine was running. I found a “hack” where I open the hood, start the car, the engine will run because the hood is open, then close the hood. The engine will turn off after a bit and go back to EV mode. I’m hoping this is only because of the wiring harness but I’m not so sure anymore. Any one experience this or know what is happening?

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r can be driven but the light will stay on. Of course I’m not feeling too confident of driving in ICE mode so I’ve tried to keep the car charged as it seems perfectly find in EV mode. The past week though even though the battery is fully charged the engine will start and sometimes after a few minutes will turn off and go back to EV mode. When this step takes too long I’ll try to drive the car but the propulsion doesn’t seem right. I couldn’t even reverse the car up a minor driveway slope when the engine was running. I found a “hack” where I open the hood, start the car, the engine will run because the hood is open, then close the hood. The engine will turn off after a bit and go back to EV mode. I’m hoping this is only because of the wiring harness but I’m not so sure anymore. Any one experience this or know what is happening?

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Turboman92 said:

I'd be curious to know why they are recommending BOTH the solenoid and the harness need to be replaced. I'd ask if they could test your current solenoid and if its bad, replace it. A harness issue should be pretty obvious.


From the Manual:

Diagnostic Fault Information

Circuit/System Description

The hybrid/EV powertrain control module 1 supplies 12 volts to the clutch pressure control solenoid valve. The hybrid/EV powertrain control module 1 controls the pressure control solenoids through the clutch pressure control solenoid valve control circuits. The normally closed pressure control solenoid valve flows fluid to the appropriate transmission hydraulic circuit when commanded ON. The clutch pressure control solenoids are part of the control solenoid valve and are not serviced separately.

Conditions for Running the DTC

Propulsion system is active. The system voltage is 9 - 16 V.

Conditions for Setting the DTC

P0964, P0968, P2718, P2727

The hybrid/EV powertrain control module 1 detects an open solenoid control circuit for 1 s.

Actions Taken When the DTC Sets

DTCs P0964, P0966, P0967, P0968, P0970, P0971, P2718, P2720, P2721, P2727, P2729, and P2730 are Type A DTCs.

P0964, P0967

• The hybrid/EV powertrain control module 1 inhibits mode 1.
• The hybrid/EV powertrain control module 1 inhibits gear 1.
• The hybrid/EV powertrain control module 1 inhibits commands the internal combustion engine On.

These three bulleted items are key.

The car is limiting the modes it can go into and the gear it can be in AND it does NOT want the engine on.


I honestly wouldn't drive it until it is fixed. You may want to consult an actual Voltec certified GM Dealer about this.

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dmtanner said:

I just got this problem (P0964) last Thursday (May 4th, 2023) on my 2017 Premier (157000km). I took it to a shop and they said there was a TSB PIC6330 issued back in April 2018 by Chevrolet and I should have been contacted to bring it in for a preventative repair. The shop contacted the Dealer's Parts department and were told the parts, transmission harness and solenoid pack were no longer available and I would have to shop around for a used one. Until then I am out-of-use of my car . They quoted me $3,300 Cdn to fix this if I ever get ahold of the parts.😱

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Turboman92 said:

Dang, I would think it would be easy enough for them to at least pull the harness, ohm it, or test connectivity on it and see.

You can try and order the solenoid HERE

However, they do show the harness as Unavailable


For what its worth, this is the first time I've seen or heard of TSV PIC6330. I've never been contacted either.


EDIT: You might have luck ordering a harness HERE. Might not be available, but worth a shot.

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dmtanner said:

What's the purpose of a TSB anyway? Shouldn't this have been a recall?

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