Diagnostic System Check - Power Seats

Circuit Description

The memory seat module (MSM) diagnostic check is an organized approach in identifying conditions associated with the module. This check must be the starting point for any MSM complaint. The check directs 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 volts

- A loose or damaged ground
- An open or a shorted serial data line

^ Detection and accurate diagnosis of an intermittent failure in the electronic system may be very difficult. The MSM tests for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often necessary 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 finding an intermittent malfunction. Faulty electrical connections or wiring causes most intermittent problems. When an intermittent condition is suspected, inspect 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-A 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. Moving related wiring and connectors may 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 instructions may result in the following conditions:

^ DTCs may set.
^ Vehicle system malfunctions may occur.
^ False DTCs may set.
^ A scan tool malfunction may occur.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

1. This test determines if communication can be established with the memory seat module (MSM).
2. This step inspects for stored MSM DTCs.
3. This test determines whether communication can be established with other modules connected to the Class 2 serial data line.
4. This step tests for any open MSM power fuses.
5. This step tests the MSM power circuit. If the test light does not turn ON, the MSM power circuit has an open.
6. This step tests the MSM ground circuit. If the test light does not turn ON, MSM power circuit has an open.