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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - Rear Wheel Steering

Circuit Description

The Rear Wheel Steering Diagnostic System Check is an organized approach to identifying problems associated with the Rear Wheel Steering System. This must be the starting point for any Rear Wheel Steering System related concern and will direct you to the next logical step in diagnosing a malfunction. Most system malfunctions are linked to faulty wiring, connections and occasionally, to components. Understanding the Rear Wheel Steering System and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

Test Description

The numbers below refer to the step numbers in the diagnostic table.

  1. Lack of communication may be due to partial or total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

    2.

  2. The symptom list in Symptoms will determine the correct diagnostic procedure to use.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

    • Turn ON the ignition with the engine OFF.
    • Use the scan tool in order to establish communication with the following modules:
      • Automatic Transfer Case (ATC)
      • Body Control Module (BCM)
      • Electronic Brake Control Module (EBCM)
      • Instrument Panel Cluster (IPC)
      • Powertrain Control Module (PCM)
      • Rear Wheel Steering Control Module
      • Sensing and Diagnostic Module (SDM)

Does the scan tool communicate with all of the control modules listed above?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Important: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.

  1. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool.
  2. Rotate the ignition switch through all positions while observing the ignition switch power mode parameter. Refer to the Serial Data Power Mode table within the Body Control System Description and Operation in Body Control Systems, for a list of the power mode states that correspond to each ignition switch position.

Does the ignition switch parameter reading match the ignition switch position for all switch positions?

Go to Step 4

Go to Power Mode Mismatch in Body Control System

4

Select the display DTCs function on the scan tool for the following control modules:

    • Automatic Transfer Case (ATC)
    • Body Control Module (BCM)
    • Electronic Brake Control Module (EBCM)
    • Instrument Panel Cluster (IPC)
    • Powertrain Control Module (PCM)
    • Rear Wheel Steering Control Module
    • Sensing and Diagnostic Module (SDM)

Does the scan tool display any DTCs for the control modules listed above?

Go to Step 5

Go to Symptoms - Rear Wheel Steering System

5

Does the scan tool display any DTCs that begin with a "U"?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Step 6

6

Does the scan tool display DTC B1000?

Go to Diagnostic Trouble Code (DTC) List in Body Control System

Go to Step 7

7

Does the scan tool display DTC B1367, P0562, P0563, P0621,P0615 , P0622, P1637, P1638?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List