Circuit Description
The starter/generator control module (SGCM) coolant pump/fan relay supplies battery voltage to the SGCM coolant pump relay and the SGCM coolant fan relay. The SGCM monitors the temperature of the low side driver for the SGCM coolant pump/fan relay. The temperature sensor of the driver is not serviceable and the data for this sensor is not available on the scan tool. This internal driver temperature sensor aids in detecting a control circuit shorted to ground or a shorted relay coil.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1AC0 Starter/Generator Control Module Output Circuit
Conditions for Running the DTC
| • | The engine has been running for 30 seconds. |
| • | The SGCM coolant pump/fan relay has been commanded ON. |
Conditions for Setting the DTC
The SGCM detects an over temperature condition of the driver for the SGCM coolant pump/fan relay.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Is the DTC set as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
3 |
Is the DTC set as a current DTC? | Go to Step 4 | Go to Step 5 |
4 | Test the SGCM coolant pump/fan relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
5 |
Important: Ensure to inspect the terminals in the electrical center. Inspect for poor connections at the connector of the SGCM coolant pump/fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the SGCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
7 | Replace the SGCM coolant pump/fan relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 9 | -- |
8 | Replace the SGCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
