POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

Has anybody had this happen? I'm trying to get some information on where to start fixing the issue.

I replaced the motor because of a stuck lifter due to not changing the oil. The transmission was not doing this before though.

When I replaced the motor my boss insisted on using the cheap green stuff instead of dexcool. Think that has anything to do with these codes?

I have a lot of information to trade, somebody please respond.... :- )

Re: POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

There must be air bubbles in the system.


The cooling for the HV power box is NOT shared with the engine.

Re: POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

Did you ever figure out what was wrong? Got the P0AC4 Code by itself

Re: POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

I recently got all those same codes. Stalled at a stop sign and I had no power. Engine revving but going nowhere. Turns out my regular battery was extremely low and I had to get a new one.

I guess the regular battery controls some of the hybrid Cooling system functions.

Re: POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

P0AC4 is a generic code that the Hybrid computer requests the main computer turn the MIL light on. Something in the hybrid system causes this request, what caused it should be stored in the computer.....even if the light turns off.

Re: POC11,13,14,16, POAC4 09 Tahoe Hybrid
 

So my vehicle died again at a stoplight. Cleaned hybrid battery vent. There wasn't much there. From what I can see, under the hood there are coolant tubes that run to the Hybrid PCM box ( black box on engine) ....these hoses were totally empty. I traced them back to two electric pumps, one behind the fan, bottom center, the other to the left near the windshield washer reservoir. These pumps go for about 150 a piece. I've wasted money replacing parts on vehicles, when it turned out to be fuses, and relays, so I found the relay in the small fuse box and switched it with the rear defrost relay. Vehicle has been running fine ever since.