For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
Circuit/System Description
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump On when the engine coolant temperature exceeds a calibrated value. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
Reference Information
Description and Operation
Cooling System Description and Operation
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTCs P2600, P2602 and P2603 are not set.
- Ignition ON, command the auxiliary coolant pump relay ON and OFF with a scan tool. Verify that the pump turns ON and OFF when changing between the commanded states.
| ⇒ | If any auxiliary coolant pump DTC is set, repair the DTC first. Refer to DTC P2600-P2603. |
| ⇒ | If the auxiliary coolant pump does not activate, refer to After Boil Coolant Pump Inoperative. |
Circuit/System Testing
- Test for a blockage or restriction in the auxiliary coolant pump lines and hoses.
- Test the pump coolant passage for a blockage or a restriction.
- Test the pump impeller for a seized or binding condition.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
