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P023A



DTC P023A

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Strategy Based Diagnosis
* Diagnostic Procedure Instructions

DTC Descriptor

DTC P023A
- Charge Air Cooler (CAC) Coolant Pump Relay Control Circuit

Diagnostic Fault Information






Circuit Description

The supercharger intercooler relay is a normally open relay. The relay armature is held in the open position by spring tension. The ignition 1 voltage is supplied directly to the relay coil and to the armature contact when the ignition is ON, or the engine is running. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module (ODM). When the engine is running, the ECM commands the relay ON, and the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into the stationary contact of the relay load circuit. The closing of the relay contacts allow current to flow from the battery to the supercharger intercooler pump. When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the ECM and the relay electromagnetic field collapses. This allows the spring tension to separate the relay armature contact from the relay load circuit contact, which interrupts current flow to the supercharger intercooler pump.

If the ECM detects an improper voltage on the supercharger intercooler pump relay control circuit for more than 30 seconds, DTC P023A sets. Refer to Boost Control System Description for further information.

Conditions for Running the DTC

* The intake air temperature (IAT) sensor 2 is greater than 0°C (32°F).
* The battery voltage is between 9-18 volts.
* The engine run time is greater than 10 seconds.
* The charge air cooler (CAC) pump relay has been commanded ON.
* The IAT is greater than -25°C (-13°F).
* DTC P023A runs continuously when the above conditions are met.

Conditions for Setting the DTC

* The ECM detects an improper voltage on the supercharger (SC) intercooler pump relay circuit.
* The condition is present for more than 30 seconds.

Action Taken When the DTC Sets

DTC P023A is a Type B DTC

Conditions for Clearing the MIL/DTC

DTC P023A is a Type B DTC

Diagnostic Aids

* A slight resistance of 1-4 ohms on the CAC pump ground circuit or the CAC pump or pump relay B+ circuits may cause this DTC to set.
* This test procedure assumes that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test. Battery Inspection/Test
* When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for correct tension.

Circuit/System Verification

Ignition ON, command the CAC coolant pump relay ON and OFF several times with a scan tool. Listen and feel for the CAC coolant pump relay to click with each command.

Circuit/System Testing

1. Ignition OFF, disconnect the CAC coolant pump relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the coil voltage supply circuit and ground.

• If the test lamp does not illuminate, test the B+ coil supply circuit for a short to ground or an open/high resistance.

4. Verify that a test lamp illuminates between the B+ switch supply circuit and ground.

• If the test lamp does not illuminate, test the B+ switch supply circuit for an open/high resistance. If the circuit tests normal and the B+ switch supply circuit fuse is open, test the CAC pump voltage supply circuit for a short to ground.

5. Disconnect the harness connector at the CAC coolant pump.
6. Test for less than 2 ohm of resistance between the CAC coolant pump ground circuit terminal 1 and ground.

• If greater than the specified range, repair the ground circuit for an open/high resistance.

7. Connect the harness connector at the CAC coolant pump.
8. Connect a 10A fused jumper wire between the B+ switch circuit and the CAC coolant pump voltage supply circuit. Verify that CAC coolant pump is activated.

• If the CAC coolant pump does not activate, test the CAC coolant voltage supply circuit for an open/high resistance. If the circuit tests normal, test the CAC coolant pump motor. Refer to Component Testing.

9. Connect a test lamp between the B+ coil supply circuit and the CAC relay control circuit.
10. Command the CAC coolant pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between commanded states.

• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
• If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

11. If all circuits test normal, test the CAC coolant pump relay. Refer to Component Testing.

Component Testing

Coolant Pump Relay
1. Ignition OFF, disconnect the CAC coolant pump relay.
2. Test between the normally-closed switch terminals, if any, for 0 ohms.
3. Test between the normally-open switch terminals for infinite ohms.
4. Test between each switch terminal and either coil terminal for infinite ohms.
5. Connect the relay coil terminals to ground and fused power to energize the relay.
6. Test between each switch terminal and each coil terminal for 0 volts.
7. Test between the normally-closed switch terminals, if any, for infinite ohms.
8. Test between the normally-open switch terminals for 0 ohms.

• If the relay fails any of the above tests, replace the relay.

CAC Pump Dynamic Test
1. Install a 10A fused jumper wire between the B+ terminal 2 and 12 volts.
2. Install a jumper wire between the ground terminal 1 and ground.
3. Observe for the CAC pump to activate.

• If the CAC pump does not activate, replace the CAC pump

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

* Refer to Programming and Relearning for ECM setup and programming. Programming and Relearning
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)
* Coolant Pump Replacement - Charge Air Cooler. Verification Tests
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