GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B1336: Device Power 3 Circuit Range

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Driver Seat Front Vertical Motor Down Control

B1336

1

--

--

Driver Seat Front Vertical Motor Up Control

B1336

1

--

--

Driver Seat Rear Vertical Motor Down Control

B1336

1

--

--

Driver Seat Rear Vertical Motor Up Control

B1336

1

--

--

Driver Seat Horizontal Motor Forward Control

B1336

1

--

--

Driver Seat Horizontal Motor Rearward Control

B1336

1

--

--

1. Power seat inoperative

Circuit/System Description

Battery positive voltage is supplied at all times to the memory seat module (MSM) through the battery positive voltage circuit through the PWR SEATS MSM circuit breaker located in the I/P fuse block. This voltage is used to power up the MSM and also to apply power to the seat motors when commanded On. The MSM applies battery voltage and ground to the seat motors through the motor control circuits. During memory recall and manual seat functions, the motor current is monitored through the motor control circuits by the MSM. When an overcurrent condition is detected by the MSM, it will disable the seat motors in order to prevent the internal MSM circuitry from damage. The MSM is grounded through the module ground circuit at G301.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

DTC B1336 will set when the MSM detects a short to ground on a motor control circuit for 100 milliseconds or more.

Actions Taken When the DTC Sets

    • The memory seat functions for the affected seat will be disabled.
    • The MSM will disable manual movements of the affected motor.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • The history DTC will clear once 50 consecutive fault-free ignition cycles have occurred.

Diagnostic Aids

The memory seat module is also referred to as the driver position module in certain scan tool menus.

Reference Information

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Memory Seats Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition ON, with a scan tool clear the current and history DTC.
  2. Determine which motor set the DTC by operating the seat motors listed below one at a time in both directions. Check for the DTC to set between each motor test.
  3. • Driver seat front vertical motor
    • Driver seat rear vertical motor
    • Driver seat horizontal motor
  4. Ignition OFF, disconnect the X3 harness connector at the MSM.
  5. Test for infinite resistance between the appropriate control circuit terminals listed below and ground:
  6. • Seat horizontal motor forward terminal N
    • Seat horizontal motor rearward terminal S
    • Seat front vertical motor upward terminal A
    • Seat front vertical motor downward terminal M
    • Seat rear vertical motor upward terminal R
    • Seat rear vertical motor downward terminal P
    If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, test or replace the appropriate seat motor.
  7. Connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the seat adjuster motor assembly.
  8. Connect a test lamp between the appropriate control circuit terminals listed below:
  9. • Seat horizontal motor terminal A and terminal B
    • Seat front vertical motor terminal C and terminal D
    • Seat rear vertical motor terminal E and terminal F
  10. Ignition ON, command the appropriate seat motor in the Forward and Rearward or Up and Down directions with a scan tool. The test lamp should turn ON when commanding the motor in the forward and rearward or up and down states.
  11. If the test lamp remains OFF during either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM.
  12. If all circuits test normal, test or replace the seat adjuster motor assembly.

Component Testing

Seat Motors

  1. Ignition OFF, disconnect the harness connector at the appropriate seat motor.
  2. Important: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.

  3. Install a 30 A fused jumper wire between one motor control terminal and 12 volts. Momentarily install a jumper wire between the other motor control terminal and ground. The seat motor should perform the appropriate UP/DOWN/FORWARD/REARWARD function.
  4. If the function does not perform as specified, replace the seat motor.
  5. Reverse the jumper wires. The seat motor should perform operate in the opposite direction.
  6. If the function does not perform as specified, replace the seat motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Seat Adjuster Motor Replacement
    •  Control Module References for MSM replacement, setup, and programming