2010 Cadillac Truck SRX FWD V6-3.0L Page 2061

2010 Cadillac Truck SRX FWD V6-3.0L Page 2061

- Auxiliary Coolant Pump Performance

DTC P2602

- Auxiliary Coolant Pump Relay Control Circuit Low Voltage

DTC P2603

- Auxiliary Coolant Pump Relay Control Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The auxiliary coolant pump and cooling fan 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 after engine shut down. The ECM applies ground to the coil side of the auxiliary pump printed circuit board (PCB) relay.

This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.

Conditions for Running the DTC

P2600, P2602, or P2603

* The engine speed is greater than 80 RPM.

* The ignition voltage is between 10-18 V.

* The ECM has commanded the pump ON and OFF at least once during the ignition cycle.

* The DTCs run continuously once the above conditions are met.

P2601

* DTC P0111, P0112, P0113, P0116, P0117, P0118, P0119, P2600, P2602, or P2603 is not set.

* The ignition is OFF.

* The engine coolant temperature (ECT) at engine shut down is warmer than 110 掳C (230 掳F).

* The auxiliary coolant pump is enabled.

* The DTC runs continuously once the conditions above are met for greater than 30 S.

Conditions for Setting the DTC

P2600

The ECM detects the pump control circuit is open. The condition exists for 4 S or a cumulative of 30 S.

P2601

The ECM detects that the ECT decreases less than 2 掳C (4 掳F) within 60 seconds. The condition exists for 4 S or a cumulative of 30 S.

P2602

The ECM detects the pump control circuit is shorted to ground. The condition exists for 4 seconds or a cumulative of 30 seconds.

P2603

The ECM detects the pump control circuit is shorted to voltage. The condition exists for 4 seconds or a cumulative of 30 seconds.

Action Taken When the DTC Sets

The DTCs are Type C DTCs.

Conditions for Clearing the DTC

The DTCs are Type C DTCs.

Diagnostic Aids

* This diagnostic uses a comprehensive approach to the diagnosis of the KR31 auxiliary coolant pump relay and its related circuits. The

auxiliary coolant pump relay is a printed circuit board (PCB) relay. The relay is an integral component to the underhood bussed electrical

center (UBEC). It cannot be removed and it is not visible.

* Much of the diagnosis is performed at the ECM connectors. Great care should be taken to ensure that the correct terminals are tested and the

proper test probes are utilized when performing this diagnostic.