For 1990-2009 cars

### 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 Descriptors

This diagnostic procedure supports the following DTCs:

DTC B1735 00: Front Vertical Up Switch Stuck
DTC B1740 00: Front Vertical Down Switch Stuck
DTC B1745 00: Rear Vertical Up Switch Stuck
DTC B1750 00: Rear Vertical Down Switch Stuck
DTC B1755 00: Horizontal Forward Switch Stuck
DTC B1760 00: Horizontal Back Switch Stuck
DTC B1815 00: Recline Up Switch Stuck
DTC B1820 00: Recline Down Switch Stuck

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Front Vertical Up Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Front Vertical Down Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Rear Vertical Up Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Rear Vertical Down Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Horizontal Forward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Horizontal Rearward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Recline Forward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
Recline Rearward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | --
1. Power seat inoperative 2. Scan Tool Does Not Communicate with Low Speed GMLAN Device

### Circuit Description

When the power seat switches are pressed, they send a 12 volt signal through the switch signal circuits to the memory seat module (MSM). The MSM then commands the driver seat motors to move in response to the switch signals.

### Conditions for Running the DTC

The MSM must be powered and cannot have DTC B1327 Battery Positive Low as an active DTC for this DTC to set.

### Conditions for Setting the DTC

• | If a seat switch circuit continues to be active for 30 seconds after a motor controlled by that switch reaches the end of its travel, the switch will be considered shorted and the MSM will set the DTC.

• | A short to voltage on a switch signal circuit.

### Action Taken When the DTC Sets

• | A motor output driven in response to a switch considered failed, is deactivated for both directions.

• | All memory recall commands are ignored.

• | The MSM will respond to any other switch signal that has not set a DTC.

### Conditions for Clearing the DTC

• | The current DTC will clear when the switch circuit setting the DTC is no longer active.

• | The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

Driver Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Power Seats System 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 Verification

Ignition ON, observe the scan tool Memory Seat Module seat switch parameters while pressing the appropriate seat directional switches. The reading should change between Inactive and Active.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Ignition ON, verify the scan tool seat switch parameters listed below are Inactive.

• | Front Vertical Switch

• | Rear Vertical Switch

• | Horizontal Switch

• | Recline Switch

⇒ | If not the specified value, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.

• | Front vertical upward switch terminal 10

• | Front vertical downward switch terminal 7

• | Rear vertical upward switch terminal 9

• | Rear vertical downward switch terminal 8

• | Horizontal forward switch terminal 3

• | Horizontal rearward switch terminal 6

• | Recline forward switch terminal 2

• | Recline rearward switch terminal 4

3. If all circuits test normal, test or replace the seat adjuster switch.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for infinite resistance between the B+ terminal 5 and each signal terminal listed below with the switch in the open position.

• | Front vertical upward switch terminal 10

• | Front vertical downward switch terminal 7

• | Rear vertical upward switch terminal 9

• | Rear vertical downward switch terminal 8

• | Horizontal forward switch terminal 3

• | Horizontal rearward switch terminal 6

• | Recline forward switch terminal 2

• | Recline rearward switch terminal 4

⇒ | If not the specified value, replace the seat adjuster switch.

3. Test for less than 1 Ω between the B+ terminal 5 and each signal terminal listed below with the appropriate switch in the closed position.

• | Front vertical upward switch terminal 10

• | Front vertical downward switch terminal 7

• | Rear vertical upward switch terminal 9

• | Rear vertical downward switch terminal 8

• | Horizontal forward switch terminal 3

• | Horizontal rearward switch terminal 6

• | Recline forward switch terminal 2

• | Recline rearward switch terminal 4

⇒ | If greater than the specified range, replace the seat adjuster switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Power Seat Switch Replacement

• | Control Module References for MSM replacement, setup, and programming