False Hybrid DTCs P2796, B3844 and/or B0979 After Failed Auto Start - keywords battery communication crank HCM IPC PHT stall
| Subject: | False Hybrid DTCs P2796 B3844 and/or B0979 After Failed Auto Start |
| Models: | 2004-2006 Chevrolet Silverado |
| 2004-2006 GMC Sierra |
| with RPO HP2 |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
The hybrid control module (HCM) has three diagnostics codes which monitor the P2796 (transmission auxiliary pump), B3844 (auxiliary coolant pump), and B0979 (120V dash button). It was discovered that these three diagnostics could run and falsely fail if the ignition key was rotated to the accessory or run position immediately following a failed auto-start.
Recommendation/Instructions:
New HCM software calibrations have been release to prevent the false setting of these DTCs. Reprogram the HCM with updated software calibrations released with TIS satellite data update version 2.5 available February 20, 2006 or later. As always, make sure your Tech 2® is updated with the latest software version.
If the DTCs do not return after the HCM software calibrations have been installed continue with normal diagnostics for the failed auto-start.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
