GM Service Manual Online
For 1990-2009 cars only

Object Number: 377727  Size: SF

Circuit Description

The power steering control module (PSCM) determines current flow of the power steering fluid flow control valve actuator (solenoid) which is relative to the vehicle speed.

The solenoid converts the electrical signal into a corresponding hydraulic control variable, which determines the amount of reaction pressure and thus the steering force.

Conditions for Setting the DTC

    • Short to ground or open in CKTs FR4 (BLK/GRY) or FY102 (BLK/PPL).
    • A defective power steering control valve actuator.

Action Taken When the DTC Sets

    • Power steering assist will default to partial manual steering effort.
    • The PSCM will store a DTC 22 in memory.

Conditions for Clearing the DTC

    • Conditions for the fault are no longer present.
    • Using the scan tool.

Diagnostic Aids

Check for the following conditions if a history or intermittent DTC is indicated.

    • A poor connection at the PSCM. Inspect the harness connectors for backed out terminals, improper mating, improperly formed or damaged terminals, and poor terminal to wire connections.
    • A damaged wiring harness. Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the actuator. A change in the DMM display during the test will indicate the location of the fault.
    • For additional information, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This test checks for an open circuit in the wiring and control valve actuator windings.

  2. This test checks for a short to ground in both circuit FY102 and FR4.

  3. Before replacing the module, check the power and ground circuits.

  4. This step determines after all repair attempts and DTC 22 is still present, that an internal malfunction exists in the Power Steering Control Module.

Step

Action

Value(s)

Yes

No

1

Was the Variable Effort Steering System Check performed?

--

Go to Step 2

Go to Variable Effort Steering System Check

2

  1. Connect the scan tool to the data link connector (DTC).
  2. Check for a current DTC 22.

Is a current DTC 22 displayed?

--

Go to Step 3

Go to Step 4

3

  1. Remove the power steering control module (PSCM).
  2. Use a DMM to measure the resistance across terminals 2 and 5 of the module connector.

Is the measured resistance within the specified value?

7-8 ohms

Go to Step 6

Go to Step 7

4

Check for a history or an intermittent DTC 22.

Is a history or an intermittent DTC 22 displayed?

--

Go to Step 5

Go to Step 6

5

  1. Locate an intermittent in circuits FR4 and/or FY102.
  2. Repair the intermittent in circuits FR4 and/or FY102.

Is the repair complete?

--

Go to Step 10

--

6

  1. Use the DMM to measure the resistance between terminal 2 of the PSCM connector and a known good ground.
  2. Use the DMM to measure the resistance between terminal 5 of the PSCM connector and a known good ground.

Is the measured resistance for both measurements within the specified value?

OL

Go to Step 8

Go to Step 9

7

  1. Locate an open or a high resistance in circuits FR4 and/or FY102.
  2. Repair the open or the high resistance in circuits FR4 and/or FY102.
  3. Replace the power steering fluid flow control valve actuator if these circuits are OK.

Is the repair or replacement complete?

--

Go to Step 10

--

8

  1. Check power and ground circuits to the module.
  2. Replace the power steering control module if power and ground is OK. Refer to Power Steering Control Module Replacement

Is the replacement complete?

--

Go to Step 10

--

9

  1. If any continuity readings were observed, locate a short to ground in circuits FR4 and/or FY102.
  2. Repair the short to ground in circuits FR4 and/or FY102.

Is the repair complete?

--

Go to Step 10

--

10

  1. Connect all connectors or components that were disconnected.
  2. Road test the vehicle.
  3. After the road test, install the scan tool again.
  4. Check for DTC 22.

Is DTC 22 displayed?

--

Go to Variable Effort Steering System Check

System OK