• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

For an overview of the component/system, refer to:Auxiliary Coolant Pump Description and Operation

• Auxiliary Coolant Pump Command=On and Off—At least 1 time(s) during the ignition cycle
• Engine Speed=Greater than 80 RPM
• Ignition Voltage=10 to 18 V

Frequency the DTC runs=Continuously—After the running conditions are met

Control Circuit=Open/High Resistance—For greater than 4 sorCumulative=30 s

Control Circuit=Short to Ground—For greater than 4 sorCumulative=30 s

Control Circuit=Short to Voltage—For greater than 4 sorCumulative=30 s

DTCs listed in the DTC Descriptor category=Type B DTC

DTCs listed in the DTC Descriptor category=Type B DTC

Engine Heating/Cooling Schematics

HVAC Schematics

Master Electrical Component List

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References

1. Ignition » On / Vehicle » In Service Mode
2. Verify that no DTC listed in the DTC Descriptor Category is set.
• If any DTC listed in the DTC Descriptor Category is set

  Refer to: Circuit/System Testing

• If none of the DTCs are set
3. Perform the scan tool control function:Auxiliary Coolant Pump»On and Off

   Verify the component turns On and Off:G36 Auxiliary Heater Coolant Pump

• If the component does not turn On and Off

  Refer to: Circuit/System Testing

• If the component turns On and Off
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

   Verify the DTC does not set.

• If the DTC sets

  Refer to: Circuit/System Testing

• If the DTC is not set
5. All OK.

1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:K20 Engine Control Module
3. Remove the component:F5UA Fuse
4. Connect a 10 A fused jumper wire between the test points:Terminal F5UA@X50A Fuse Block - Underhood&B+
5. Ignition » On / Vehicle » In Service Mode
6. Momentarily connect a 10 A fused jumper wire between the test points:Control circuit terminal X2 33@Control module harness&Ground

   Verify the component turns On and Off when connecting and disconnecting the jumper wire:G36 Auxiliary Heater Coolant Pump

• If the component does not turn On and Off
1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
2. Test for infinite resistance between the test points:Control circuit terminal X2 33@Control module harness&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
3. Disconnect the electrical connector:X2&X3@X50A Fuse Block - Underhood
4. Test for less than 2 Ω between the test points:
• Terminal X3 17@Fuse/Junction Block Harness&Control circuit terminal X2 33@Control module harness
• Terminal X2 66@Fuse/Junction Block Harness&Terminal X2 67@Fuse/Junction Block Harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω
5. Test for less than 2 Ω between the test points:
• Terminal X3 17@X50A Fuse Block - Underhood&Terminal X2 66@X50A Fuse Block - Underhood
• Terminal X2 67@X50A Fuse Block - Underhood&Terminal F5UA@X50A Fuse Block - Underhood
• If 2 Ω or greater » Replace the component:X50A Fuse Block - Underhood
• If less than 2 Ω
6. Replace the component:K20 Engine Control Module
• If the component turns On and Off
7. Replace the component:K20 Engine Control Module

1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:G36 Auxiliary Heater Coolant Pump
3. Connect a jumper wire between the test points:Ground terminal 1&Ground
4. Momentarily connect a 10 A fused jumper wire between the test points:Control terminal 2&12 V

   Verify the component turns On and Off when connecting and disconnecting the jumper wire:G36 Auxiliary Heater Coolant Pump

• If the component does not turn On and Off

  Replace the component:G36 Auxiliary Heater Coolant Pump

• If the component turns On and Off
5. All OK.

Perform the Diagnostic Repair Verification after completing the repair:Diagnostic Repair Verification

• Auxiliary Water Pump Replacement
• Battery Distribution Engine Compartment Fuse Block Replacement
• For control module replacement, programming, and setup refer to:Control Module References