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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Seat Adjuster Switch B+ | 1 | 1 | -- | --
Seat Front Vertical Motor Down Control | 1 | 1 | 1 | --
Seat Front Vertical Motor Up Control | 1 | 1 | 1 | --
Seat Adjuster Switch Ground | -- | 1 | -- | --
1. Power Seat Inoperative

### Circuit/System Description

When the seat switch is operated to lift the seat cushion up, battery positive voltage is applied from the PWR SEATS 20 A circuit breaker through the UP switch contacts to the vertical motor up control circuit. The motor is grounded through the down switch contacts and the vertical motor down control circuit. The motor runs in order to drive the seat cushion up until the switch is released. Lowering the seat cushion works similarly to lifting the seat cushion, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction. Ground for the seat adjuster switches is supplied at ground G300.

### Reference Information

#### Schematic Reference

Driver Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Power Seats System 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 OFF, disconnect the harness connector at the Seat adjuster switch.
2. Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal A and ground.

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

3. Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal G and ground.

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

4. Verify that a test lamp illuminates between the B+ circuit terminal F and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. Connect the harness connector at the Seat adjuster switch.
6. Disconnect the harness connector at the seat front vertical motor.
7. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
8. Command the seat UP and DOWN with the seat adjuster switch. The test lamp should turn ON when commanding the seat UP and DOWN.

⇒ | If the test lamp remains OFF during either of the commands, test both control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the seat adjuster switch.

⇒ | If the test lamp is always ON, test both control circuits for a short to voltage. If the circuits test normal, test or replace the seat adjuster switch.

9. If all circuits test normal, test or replace the seat front vertical motor.

### Component Testing

Important: When performing the following tests, make sure that the device is not all ready in the position the test is attempting to produce.

1. Ignition OFF, disconnect the harness connector at the seat front vertical motor.
2. Install a 20A fused jumper wire between the control terminal 1 and B+. Momentarily install a jumper wire between the control terminal 5 and ground. The seat motor should move UP.

⇒ | If the function does not perform as specified, replace the seat front vertical motor.

3. Install a 20A fused jumper wire between the control terminal 5 and B+. Momentarily install a jumper wire between the control terminal 1 and ground. The seat motor should move DOWN.

⇒ | If the function does not perform as specified, replace the seat front vertical motor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Power Seat Switch Replacement

• | Seat Adjuster Motor Replacement