GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The following DTCs are for the internal fluid temperature sensors located internal to the starter/generator control module (SGCM):

    • P0A01 is for the internal fluid temperature sensor 1 performance.
    • P0A02 is for the internal fluid temperature sensor 1 high temperature.
    • P0A03 is for the internal fluid temperature sensor 1 low temperature.
    • P1A7A is for the internal fluid temperature sensor 3 low temperature.
    • P1A75 is for the internal fluid temperature sensor 2 performance.
    • P1A76 is for the internal fluid temperature sensor 2 high temperature.
    • P1A77 is for the internal fluid temperature sensor 2 low temperature.
    • P1A78 is for the internal fluid temperature sensor 3 performance.
    • P1A79 is for the internal fluid temperature sensor 3 high temperature.

The SGCM monitors its internal fluid temperature sensors to control the SGCM coolant pump and SGCM cooling fan. The internal fluid temperature sensors of the SGCM are thermistors and are not serviceable. When the internal fluid temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the internal fluid temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The input parameters are not displayed on the scan tool.

Conditions for Running the DTC

    • The engine has been running for 30 seconds.
    • The SGCM has received voltage on the ignition 0 voltage circuit.
    • The SGCM has turned ON and no configuration DTC are present.

Conditions for Setting the DTC

    • For low temperature DTC the monitored internal fluid temperature of the sensor is below -40°C (-40°F).
    • For high temperature DTC the monitored internal fluid temperature of the sensor is above 125°C (257°F)
    • For performance DTC the monitored average internal fluid temperature of the sensor is 15°C (27°F) different than average of the all internal fluid temperature sensors.

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

Was the Engine Cooling Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

2

  1. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
  2. With a scan tool, observe the SGCM DTC list.

Is the DTC set as current DTC?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

With a scan tool, command the starter/generator control module (SGCM) cooling fan ON and OFF.

Does the SGCM cooling fan turn ON and OFF with each command?

Go to Step 4

Go to Starter Generator Control Module Cooling Fan Inoperative

4

With a scan tool, command the SGCM Coolant Pump ON and OFF.

Does the SGCM coolant pump turn ON and OFF with each command?

Go to Step 5

Go to Starter Generator Control Module Coolant Pump Inoperative

5

Inspect for poor connections at the harness connector of the SGCM . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Important: Perform the programming procedure for the SGCM.

Replace the SGCM. Refer to Generator Control Module Replacement in Engine Electrical.

Did you complete the replacement?

Go to Step 7

--

7

  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK