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 | -- | --
Front Vertical Motor Front Down Control | 1 | 1 | -- | --
Front Vertical Motor Front Up Control | 1 | 1 | -- | --
Horizontal Motor Forward Control | 1 | 1 | -- | --
Horizontal Motor Rearward Control | 1 | 1 | -- | --
Rear Vertical Motor Rear Down Control | 1 | 1 | -- | --
Rear Vertical Motor Rear Up Control | 1 | 1 | -- | --
Seat Adjuster Switch Ground | -- | 1 | -- | --
1. Power seat inoperative

### Circuit/System Description

The power seat is controlled through the seat adjuster switch. Battery voltage is supplied at all times to the seat adjuster switch through the POWER SEAT 25A circuit breaker located in the I/P fuse block. When the seat adjuster switches are in an inactive state, the switch contacts are closed to the switch ground circuit.

All seat motors are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, battery voltage is applied through the switch contacts and the seat horizontal motor forward control circuit to the motor. The motor is grounded through the horizontal motor rearward switch contacts and the horizontal motor rearward control circuit to the motor. The motor runs in order to drive the entire seat forward until the switch is released. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction. All seat motors are powered this way.

### 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

### Circuit/System Verification

1. Operate the switches for the seat directional motors listed below in both directions. The seat should move in the commanded directions.

• | Horizontal Motor

• | Front Vertical Motor

• | Rear Vertical Motor

⇒ | If the power seat is inoperative in all directions, refer to the Seat Adjuster Switch Circuit Test.

⇒ | If the seat front or rear vertical adjuster motor is inoperative, refer to the Seat Vertical Motor Circuit Test.

⇒ | If the seat horizontal motor is inoperative, refer to the Seat Horizontal Motor Circuit Test.

### Circuit/System Testing

#### Seat Adjuster Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for less than 10 Ω between the ground circuit terminal B and ground.

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

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal D and ground.

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

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

#### Seat Vertical Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate seat vertical motor.
2. Connect a test lamp between control circuit terminal 1 or A and control circuit terminal 2 or B.
3. Ignition ON, command the appropriate seat motor in the UP and DOWN directions using the seat adjuster switch. The test lamp should turn ON when commanding the UP and DOWN states.

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

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

#### Seat Horizontal Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.

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

2. Install a 30 A fused jumper wire between control terminal C and 12 V. Momentarily install a jumper wire between control terminal F and ground. The seat horizontal motor should momentarily perform the FORWARD function.

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

3. Reverse the polarity of jumper wires; the a seat horizontal motor should perform the REARWARD function.

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

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

### Component Testing

#### Driver Seat Adjuster Switch

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

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

3. Test for less than 2 Ω between each control terminal and the B+ terminal D with the switch in the closed position.

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

4. Test for less than 2 Ω between each control terminal and the ground terminal B with the switch in the open position.

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

#### Seat Vertical Motor

1. Ignition OFF, disconnect the harness connector at the appropriate seat motor.

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

2. Install a 30 A fused jumper wire between control terminal 2 or B and 12 V. Momentarily install a jumper wire between control terminal 1 or A and ground. The seat vertical motor should momentarily perform the UP function.

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

3. Reverse the polarity of jumper wires; the a seat vertical motor should perform the DOWN function.

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

#### Seat Horizontal Motor

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.

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

2. Install a 30 A fused jumper wire between control terminal C and 12 V. Momentarily install a jumper wire between control terminal F and ground. The seat horizontal motor should momentarily perform the FORWARD function.

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

3. Reverse the polarity of jumper wires; the a seat horizontal motor should perform the REARWARD function.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Power Seat Switch Replacement

• | Front Seat Adjuster Replacement