GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The power steering control module (PSCM) has a discrete battery voltage supply circuit. The PSCM monitors the voltage level on this circuit to protect itself against high voltage damage.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0900 Device 1 Voltage High

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description .

DTC Symptom

DTC Symptom Descriptor

00

No Additional DTC Information

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

Power Steering System voltage is greater than 16 volts for at least 1 second.

Action Taken When the DTC Sets

    • DTC C0900 00 is stored in memory.
    • The DIC displays the POWER STEERING warning message.
    • The PSCM is disabled to protect itself.
    • No steering assist is provided.

Conditions for Clearing the MIL/DTC

    • A current DTC will clear when the Power Steering System voltage returns to less than 16 volts.
    • A history DTC will clear after 100 consecutive ignition cycles from when Power Steering System voltage is less than 16 volts.
    • Using a scan tool

Diagnostic Aids

Jump starting the vehicle, or turning ON the ignition while charging the vehicles battery can cause DTC C0900 00 to set.

Step

Action

Values

Yes

No

Schematic Reference: Power Steering Schematics

Connector End Views Reference: Power Steering Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Battery Voltage parameter in the Power Steering data list.

Does the scan tool indicate that the Battery Voltage parameter is greater than the specified value?

16 V

Go to Step 3

Go to Diagnostic Aids

3

Inspect for poor connections at the ground terminal G103. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

 

Go to Step 7

Go to Step 4

4

Inspect for poor connections at the power steering control module (PSCM) harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

 

Go to Step 7

Go to Step 5

5

Test the ground circuit of the PSCM for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

 

Go to Step 7

Go to Step 6

6

Replace the power steering motor and module assembly. Refer to Power Steering Assist Motor Replacement .

Did you complete the replacement?

 

Go to Step 7

--

7

  1. Use the scan tool in order to clear the DTC.
  2. Operate the vehicle within the conditions for running the DTC.

Does the DTC reset?

 

Go to Step 2

System OK