Cobalt Hybrid Hijinks

The owner of a 2008 Chevy Cobalt hybrid may note a chuggle or stall when coming to a stop. The engine will restart. The engine tachometer will drop to zero and not AutoStop.

April 10, 2017

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The owner of a 2008 Chevy Cobalt hybrid may note a chuggle or stall when coming to a stop. The engine will restart. The engine tachometer will drop to zero and not AutoStop.

There would not be a command for an auto-stop. The engine may restart using the 12V starter and set a DTC P1A6F. This may lead the technician to incorrectly suspect the hybrid components.

A partially or momentarily applied TCC may be caused by a restriction in the transmission cooling system. Note that a possible restriction in the transmission cooling system may not allow a sufficient volume of fluid to properly release the TCC.

To properly diagnose for possible restriction in the transmission cooling system, complete the following:

Use J45096 or equivalent to flow test the transmission oil cooler pipes.
If the flow rate is below minimum, check for cooler restriction, cooler lines bent or kinked, and transmission cooler fluid line passages behind the fittings.