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
--- | --- | --- | --- | ---
B+, Seat Adjuster Switch | 1, 2 | 1 | -- | --
Front Vertical Motor Down Control | 1 | 1 | -- | --
Front Vertical Motor Up Control | 1 | 1 | -- | --
Horizontal Motor Forward Control | 1 | 1 | -- | --
Horizontal Motor Rearward Control | 1 | 1 | -- | --
Rear Vertical Motor Down Control | 1 | 1 | -- | --
Rear Vertical Motor Up Control | 1 | 1 | -- | --
Recline Motor Forward Control | 1 | 1 | -- | --
Recline Motor Rearward Control | 1 | 1 | -- | --
Ground - Seat Adjuster Switch | -- | 1 | -- | --
1. Power Seats Inoperative 2. Lumbar Support Inoperative

### Circuit/System Description

The power seats are controlled through the seat adjuster switch. Battery voltage is supplied at all times to the seat adjuster switches through the PWR/SEAT 40A fuse located in the underhood fuse block. While the seat 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

• | Passenger 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

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

• | Seat Horizontal Motor

• | Seat Front Vertical Motor

• | Seat Rear Vertical Motor

• | Seat Recline Motor

⇒ | If all power seat functions are inoperative, refer to the Seat Adjuster Switch Circuit Test.

⇒ | If just the seat recline function is inoperative, refer to Seat Recline Motor Circuit Test.

⇒ | If 1 or more of the seat adjuster motors operate, refer to the Seat Adjuster Motor Circuit Test.

### Circuit/System Testing

#### Seat Adjuster Switch Circuit Test.

1. Ignition OFF, disconnect the X1 harness connector at the appropriate seat adjuster switch.
2. Test for less than 1 ohm between the appropriate ground circuit listed below and ground.

• | Driver seat terminal H

• | Passenger seat terminal D

⇒ | 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 A 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 Recline Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat recline motor.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, command the seat recline motor Forward and Rearward using the seat recline switch. The test lamp should turn ON when commanding the forward and rearward 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 the circuits test normal, test or replace the seat recline motor.

#### Seat Adjuster Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster motor assembly.
2. Connect a test lamp between the appropriate control circuits listed below:

• | Seat horizontal motor terminal D and terminal E

• | Seat front vertical motor terminal F and terminal G

• | Seat rear vertical motor terminal B and terminal C

3. Ignition ON, command the appropriate seat motor Up and Down or Forward and Rearward using the seat adjuster switch. The test lamp should turn ON when commanding the up and down or forward and rearward 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 test normal, test or replace the seat motor.

### Component Testing

#### Seat Adjuster Switch

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

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

3. Test for less than 1 ohm between the B+ terminal and each control terminal with the switch in the closed position.

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

4. Test for less than 1 ohm between the ground terminal and each control terminal with the switch in the open position.

⇒ | 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

• | Power Seat Adjuster Mechanism Replacement