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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Hybrid Engine Cooling System) >> Diagnostic Information and Procedures >> Hybrid Cooling System Overheating (Mechanical)

Hybrid Cooling System Overheating (Mechanical)

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
Step Action Yes No
1 Inspect for a missing or damaged radiator side or upper baffle and/or radiator air deflector.
Is the baffle and/or deflector missing or damaged?
Go to Step 10  Go to Step 2 
2 Inspect for a loss of coolant.
Is there a loss of coolant?
Go to Step 3  Go to Step 4 
3 Fill the system to the specified level.
Does the hybrid cooling system overheat?
Go to Step 4  System OK
4 Inspect for low temperature protection.
Is the coolant to the correct concentration?
Go to Step 5  Go to Step 10 
5 Inspect for a loss of cooling system pressure.
Is there a loss of system pressure?
Go to Step 10  Go to Step 6 
6 Inspect for a faulty coolant temperature sensor. Refer to DTC P0A01-P0A03 .
Is the sensor operating properly?
Go to Step 7  Go to Step 8 
7 Inspect for the following:
  • Damaged coolant surge tank
  • Leaking hose
  • Bad/incorrect surge tank cap

Were any of the above found?
Go to Step 10  Go to Step 3 
8 Inspect the auxiliary coolant pumps for proper operation.
Is the pump operating properly?
Go to Step 9  Go to Step 10 
9 Inspect for obstructed radiator air flow or bent radiator fins.
Is the radiator air flow obstructed?
Go to Step 10  -
10 Repair or install new parts as necessary, then retest. - System OK