CUSTOMER CONCERN The engine intermittently will not crank and may stall while driving; DTCs P1682, P0AC4, P069E and P2534 are stored across the ECM, FPFCM and HPCM. CAUSE The confirmed repair identified an intermittent ignition-switch fault that dropped ignition voltage and caused the module low-voltage and communication symptoms. CORRECTION Remove and replace the failed ignition switch, clear P1682, P0AC4, P069E and P2534, and road test to verify the engine no longer stalls

CUSTOMER CONCERN Vehicle intermittently will not crank and may stall while driving with DTCs P1682, P0AC4, P069E, and P2534 stored. CAUSE Confirmed repair results identified an intermittent internal failure of the ignition switch. CORRECTION Remove and replace the ignition switch and verify reliable starting and continued engine operation.

CUSTOMER CONCERN The 12-volt charging system is inoperative and DTCs P0AC4, U0293, and U1817 are stored. CAUSE The Hybrid Powertrain Control Module would not communicate even though its power and ground circuits were present, DLC terminals 6 and 14 measured 60 ohms, and other high-speed GMLAN modules communicated normally. Testing confirmed an internal HPCM/Starter Generator Control Module failure. CORRECTION Remove and replace the Hybrid Powertrain Control Module/Starter Gen

CUSTOMER CONCERN ABS and traction-control warning lights are on with DTCs P0AC4 and U1820. CAUSE Testing isolated the fault to the Electronic Brake Control Module connector and the EBCM. CORRECTION Repair the EBCM connector and remove and replace the failed Electronic Brake Control Module.

CUSTOMER CONCERN The check engine light is on with DTCs P0AC4 and P183E stored. CAUSE Transmission range data confirmed an internal mode switch that did not report the selected gear range correctly. CORRECTION Remove and replace the transmission internal mode switch.

CUSTOMER CONCERN Customer states the vehicle will not crank. DTCs P0AC4, U1888, U1875 and U1878 are stored. CAUSE DLC resistance, fuse-feed and expansion-bus testing isolated an open or high-resistance circuit in the drive-motor generator power-inverter module wiring. CORRECTION Repair drive-motor generator power-inverter module wiring and connector terminals. Clear network and hybrid DTCs and verify module communication and normal cranking.

CUSTOMER CONCERN Customer states the malfunction indicator light is on with DTCs P0A93 and P0AC4, and the vehicle will not complete its emissions test. CAUSE The inverter cooling reservoir was empty, and inspection confirmed coolant leaking from an inverter cooling-system hose. CORRECTION Repair leaking inverter cooling-system hose. Refill and bleed inverter cooling circuit, clear DTCs P0A93 and P0AC4 and verify coolant circulation.

CUSTOMER CONCERN Customer states the vehicle has low power. DTCs P061B and P0AC4 are stored. CAUSE Hybrid-system DTC and battery-pack testing confirmed deterioration inside the high-voltage hybrid battery pack. CORRECTION Remove and replace high-voltage hybrid battery pack. Perform required module setup and clear hybrid-system DTCs.

CUSTOMER CONCERN Customer states the engine stalls when stopping instead of completing a normal Auto Stop. Multiple ECM, HPCM and TCM communication DTCs are stored. CAUSE Inspection following bulletin 08-07-30-021H confirmed chafed high-speed CAN wiring causing intermittent module communication loss. CORRECTION Repair chafed high-speed CAN wiring and protect harness from repeat contact. Clear communication DTCs and verify normal Auto Stop operation.

CUSTOMER CONCERN Customer states the malfunction indicator light is on with DTCs P0A93 and P0AC4, and the vehicle will not complete its emissions test. CAUSE The inverter cooling-system reservoir was empty, and inspection confirmed coolant leaking from an inverter cooling-system hose. CORRECTION Repair leaking inverter cooling-system hose. Refill and bleed inverter cooling circuit. Clear hybrid-system DTCs.