[gerardjg]

Hello thanks in advance for any help on this one, the sun roof drain clogged the rear right one causing the trunk to fill up with water. The floor on the rear passenger side was also flooded After removing seats and carpet drying everything out the Car ran for several days it now has the engine disabled warning and reduced power warning intermittently. error code P0601. I can clear the code start and use the car once I shut it it will either not start or start and shut down after a few minutes clear the code and it will run fine again for awhile. The amperage sensor on the negative battery cable was under water and I replaced that . I have 5 V at the maf and throttle body could the wire harness under the carpet being partially submerged cause the PCM to fail? Any suggestions where to look next.

2005 Cobalt 146,000 miles

 

[CodyATE6]

Body control module is a likely module to be damaged in the interior. Although I’d think it sits high enough up that it won’t have been exposed to the water. The wiring in the trunk, headliner, under the carpet, could be wet still and causing a short. Anything that is being shorted and is connected to a module will have the possibility to cause damage to the module.

Just for instance if the transmission module is shorted or damaged it can cause a problem with the PCM, even if there is no problem with the PCM and the problem was really in the TCM. You may have something as simple as a corroded ground wire in the trunk, so I’d start cleaning the battery cables first. Even a small bit of corrosion can cause the PCM to go crazy.

 

[gerardjg]

Thank you this weekend I will remove the seats and carpet and hopefully find something , I did clean all the connections and grounds within trunk. The car is very low usage now but for 13 plus years it was a extremely reliable every day driver that is why I kept it.

 

[gerardjg]

I finally had some time to look at this we put the car indoors and ran a heater in it for several days, cleaned grounds and all connectors in the trunk area, the car will start and run fine if we clear the code or turn the key before the Reduced Power engine disabled message appears. Once we put it into gear the car shuts down. Only error code P0601, All eight 5volt reference circuits test good.
If I put a TCM and PCM in from another same year cobalt for trouble shooting would I be doing any harm?

 

[gerardjg]

I purchased an ECM online programmed to my vin , After install car started all codes are clear except a new code for Crankshaft relearn po315. After research, relearn needs to be completed after replacing the ECM. Hopefully once the relearn is complete all will be back to normal.