GM Service Manual Online
For 1990-2009 cars only

The following test steps must be performed in the given order. If a fault is found in one step, the subsequent steps can be skipped.

Tools Required

Scan Tool Tech 2

Important: Before proceeding with the steps below, ensure: There are no stored diagnostic trouble codes stored in electro-hydraulic power steering (EHPS).

Circuit/System Testing

Actual Pump Motor Current

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF with a scan tool verify Actual Motor Current to be 0 Amps
  2. Ignition ON, Engine ON, All accessories OFF, the Actual Motor Current should be 4 to 5 Amps.
  3. Turn steering wheel right until stop, turn slightly further and hold firmly in this position. The Actual Motor Current should be between 55-65 Amps.
  4. Turn steering wheel left until stop, turn slightly further and hold firmly in this position. The Actual Motor Current should be between 55-65 Amps.
  5. If the amperage is not within the specified range, replace the power steering control module.

Desired Pump Speed

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF with a scan tool verify the Desired Pump Speed is 0.
  2. Engine Running, with a scan tool verify the Desired Pump Speed is 2660.
  3. If the RPM is not specified value, replace the power steering control module.
    If the RPM is the specified value, refer to the Actual Pump Speed.

Actual Pump Speed

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF, with a scan tool verify the Actual Pump Speed is 0.
  2. Engine Running, with a scan tool verify the Actual Pump Speed is 2655-2665 RPM.
  3. If the RPM is not within the specified range, replace the power steering control module.