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.