GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Rendezvous - FWD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1770, B1775, B1780, B1785, B1790, B1805, or B2415

Circuit Description

The seat adjuster motors are controlled by the memory seat module (MSM) through the adjuster motor control circuits. The MSM also monitors current flow through the adjuster motor control circuits. In an inactive state the control circuits are closed to ground within the MSM. In an active state the appropriate adjuster motor control circuit is switched to battery voltage within the MSM. The direction of the adjuster motor rotation is determined by which of the control circuits is switched to battery voltage while the other remains grounded.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B1770 Driver Seat Motor Horizontal Circuit
    • DTC B1775 Driver Seat Motor Front Vertical Circuit
    • DTC B1780 Driver Seat Motor Rear Vertical Circuit
    • DTC B1785 Driver Seat Motor Recline Circuit

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

The adjuster motor control circuit current monitored by the memory seat module is high, low, or open.

Action Taken When the DTC Sets
    • The MSM will disable the seat adjuster motor for which a current status DTC is set.
    • When the fault is no longer present a history status DTC will be stored, and adjuster motor operation will be restored.

Conditions for Clearing the DTC
    • The DTC will be current for as long as the fault is present.
    • When the fault is no longer present the DTC will be a history status code.
    • The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

Test Description

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

  1. Verify that the DTC is current or history by attempting to operate the seat adjuster motor for which the code is set.

    2.

  2. Tests the adjuster motor supply circuits for proper operation.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. With a scan tool, operate the seat adjuster motor through the full range of adjustment in both directions.

Does the seat adjuster motor operate through the full range of adjustment?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Disconnect the seat adjuster motor assembly connector.
  2. Connect a test lamp between the affected adjuster motor control circuit terminals in the seat harness connector.
  3. With a scan tool, command the adjuster motor active in both directions.

Does the test lamp turn ON and OFF with each command?

Go to Step 5

Go to Step 4

4

Test and repair the adjuster motor control circuits for the following conditions:

    • Short to ground
    • Open or high resistance
    • Short to voltage

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 6

5

Inspect for poor connections at the adjuster motor assembly connector. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the harness connector of the memory seat module (MSM). Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the seat adjuster assembly. Refer to Front Seat Adjuster Replacement .

Did you complete the replacement?

Go to Step 9

--

8

Replace the MSM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

9
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the system in order to verify the repair.

Does the DTC reset?

Go to Step 2

System OK