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 B1825 00: Recline Position Sensor Fault
DTC B2355 00: Front Vertical Position Sensor Fault
DTC B2365 00: Rear Vertical Position Sensor Fault
DTC B2375 00: Horizontal Position Sensor Fault

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Front Vertical Motor Position Sensor 5 V Reference | B2355 00 | B2355 00 | B2355 00 | --
Front Vertical Motor Position Sensor Signal | B2355 00 | B2355 00 | B2355 00 | --
Front Vertical Motor Position Sensor Ground | -- | B2355 00 | -- | --
Horizontal Motor Position Sensor Signal | B2375 00 | B2375 00 | B2375 00 | --
Horizontal Motor Position Sensor Ground | -- | B2375 00 | -- | --
Rear Vertical Motor Position Sensor 5 V Reference | B2365 00 | B2365 00 | B2365 00 | --
Rear Vertical Motor Position Sensor Signal | B2365 00 | B2365 00 | B2365 00 | --
Rear Vertical Motor Position Sensor Ground | -- | B2365 00 | -- | --
Recline Motor Position Sensor Signal | B1825 00 | B1825 00 | B1825 00 | --
Recline Motor Position Sensor Ground | -- | B1825 00 | -- | --

### Circuit Description

The seat and lumbar motors are equipped with position sensors internal to the motor. The sensors are monitored by the memory seat module (MSM) and are used to determine seat positions when storing or recalling memory settings. The seat front vertical and rear vertical motors use 3 wire hall effect type position sensors while the seat horizontal and recline motors use 2 wire hall effect type position sensors. The MSM supplies the 3 wire hall effect position sensors with a separate 5 V reference circuit and signal circuit while ground is provided at G304. The MSM supplies the 2 wire hall effect position sensors with a signal circuit while ground is also provided at G304. During seat motor operation, the hall effect position sensor provides a determined number of pulse signals for every revolution of the motor shaft. These pulse signals (Steps) range from 0 - 65,535. High scan tool step values indicate forward or upward seat positions while low step values indicate rearward or downward seat positions.

### Conditions for Running the DTC

The MSM must be powered and can not have B1327 as an active DTC for this DTC to set.

### Conditions for Setting the DTC

The MSM does not detect position sensor movement while the adjuster motor is active.

### Action Taken When the DTC Sets

The MSM disables the memory recall commands of the motor monitored by the sensor. The motor will respond to manual positioning commands.

### Conditions for Clearing the DTC

• | The DTC will clear when the fault is no longer present.

• | 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

1. Ignition ON, observe the scan tool seat position sensor parameters listed below while commanding the appropriate seat motor Up and Down or Forward and Rearward using the seat adjuster switch. Each parameter should change between 0 and 65,535 Steps.

• | Front Vertical Position Sensor

• | Horizontal Position Sensor

• | Rear Vertical Position Sensor

• | Recline Position Sensor

### Circuit/System Testing

#### B1825 00 or B2375 00

1. Ignition OFF, disconnect the harness connector at the appropriate seat motor.
2. Test for less than 5.0 Ω between the appropriate ground circuit terminal listed below and ground.

• | Seat horizontal sensor terminal 3

• | Seat recline sensor terminal 2

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for 4.8 - 5.2 V between the 5 V reference circuit terminal 4 and ground while commanding the seat motor ON with a scan tool.

⇒ | If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

⇒ | If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.

4. If all circuits test normal, test or replace the appropriate motor.

#### B2355 00 or B2365 00

1. Ignition OFF, disconnect the harness connector at the appropriate seat motor.
2. Test for less than 5.0 Ω between the ground circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for 4.8 - 5.2 V between the 5 V reference circuit terminal 4 and ground while commanding the seat motor ON with a scan tool.

⇒ | If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

⇒ | If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.

4. Test for 4.8 - 5.2 V between the signal circuit terminal 3 and ground while commanding the seat motor ON with a scan tool.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the MSM.

5. If all circuits test normal, test or replace the appropriate seat motor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Seat Adjuster Motor Replacement - Horizontal

• | Seat Adjuster Motor Replacement - Vertical

• | Front Seat Horizontal Adjuster Position Sensor Replacement

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