GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The memory seat module (MSM) diagnostic check is an organized approach to identify problems associated with the module. This check must be the starting point for any MSM complaint, and will direct you to the next logical step in diagnosing the complaint. The MSM is a very reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to components. Understanding the computer system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

Diagnostic Aids

    • The following conditions may result in an intermittent operation of the module with no DTC stored:
       - Any condition which results in the interruption of power to the MSM
       - Out of range battery or ignition voltage

Specification
Normal MSM operating voltage: 9.0-16.0 V

       - A loose or damaged ground(s)
       - An open or shorted serial data line
    • An intermittent failure in the electronic system may be very difficult to detect and to accurately diagnose. The MSM tests for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a malfunction. If the system malfunction is not repeated during the test drive, a good description of the complaint may be very useful in locating an intermittent malfunction. Faulty electrical connections or wiring causes most intermitting problems. When an intermitting condition is suspected, check the suspected circuits for the following conditions:
       - Poor mating of connector halves or backed out terminals
       - Improperly formed or damaged terminals
       - Wire chafing
       - Poor wire to terminal connections
       - Dirty or corroded terminals
       - Damage to connector bodies
    • Use the J 35616 whenever a diagnostic procedure requests probing or checking a terminal. Using this adapter will ensure that no damage to the terminal will occur, and will give an idea of whether contact tension is sufficient.
    • If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Perform a thorough inspection of all related wiring and connectors pertaining to the history DTC stored.
    • Exit all scan tool tests before cycling the ignition OFF to ON unless the scan tool instructions direct otherwise. Follow the operating instructions in the scan tool operator's manual. Failure to follow these instruction may set DTCs, cause vehicle system malfunctions, set false DTCs, or cause scan tool malfunctions.

Test Description

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

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

  2. The Symptom Table will determine the correct diagnostic procedure to use.

  3. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

  4. This step determines if any internal controller DTCs are set.

  5. This steps determines if any system voltage DTCs are set.

Step

Action

Yes

No

1

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

Does the scan tool power up?

Go to Step 2

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

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the Memory Seat Module, Driver Door Module and the Rear Integration Module.

Does the scan tool communicate with the Memory Seat Module, Driver Door Module and the Rear Integration Modules?

Go to Step 3

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

3

Select the Memory Seat Module display DTC function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms

4

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

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

Go to Step 5

5

Does the scan tool display DTC B1000, B1004, B1007, or B1009?

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

Go to Step 6

6

Does the scan tool display DTC B1327?

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

Go to Diagnostic Trouble Code (DTC) List/Type