Power Seat Inoperative Without Memory A45

Power seat without memory is completely controlled through the seat adjuster switch. Battery voltage is supplied at all times to the seat adjuster switch from the 30A PWR SEATS circuit breaker that is located in the left rear 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.

Schematic Reference

Passenger Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Seats System Description and Operation

Electrical Information Reference

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

1. Horizontal Motor
2. Front Vertical Motor
3. Rear Vertical Motor
4. Recline Motor

Recliner Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the recline motor.
2. Verify that the test lamp illuminates between control circuit terminal A and control circuit terminal B while pressing the recline switch in both directions.

⇒	If the test lamp does not illuminate for both directions, 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.

3. If all circuits test normal, test or replace the recline motor.

Seat Adjuster Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Test for less than 5 ohms between the ground circuit terminal D 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 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 Adjuster Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster motor assembly.
2. Verify that a test lamp illuminates between the appropriate control circuits listed below while pressing the seat switch in both directions.

•	Seat horizontal motor terminal 3 and terminal 6

•	Seat front vertical motor terminal 2 and terminal 5

•	Seat rear vertical motor terminal 1 and terminal 4

⇒	If the test lamp does not illuminate for both directions, 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.

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

Seat Adjuster Switch

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

•	Seat horizontal forward switch terminal C

•	Seat horizontal rearward switch terminal B

•	Seat front vertical upward switch terminal G

•	Seat front vertical downward switch terminal F

•	Seat rear vertical upward switch terminal J

•	Seat rear vertical downward switch terminal H

•	Seat recline forward switch terminal K

•	Seat recline rearward switch terminal E

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

3. Test for less than 1 ohm between each seat direction signal terminal listed below and the B+ terminal A with the switch in the closed position.

•	Seat horizontal forward switch terminal C

•	Seat horizontal rearward switch terminal B

•	Seat front vertical upward switch terminal G

•	Seat front vertical downward switch terminal F

•	Seat rear vertical upward switch terminal J

•	Seat rear vertical downward switch terminal H

•	Seat recline forward switch terminal K

•	Seat recline rearward switch terminal E

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

4. Test for less than 1 ohm between each seat direction signal terminal listed below and the ground terminal D with the switch in the open position

•	Seat horizontal forward switch terminal C

•	Seat horizontal rearward switch terminal B

•	Seat front vertical upward switch terminal G

•	Seat front vertical downward switch terminal F

•	Seat rear vertical upward switch terminal J

•	Seat rear vertical downward switch terminal H

•	Seat recline forward switch terminal K

•	Seat recline rearward switch terminal E

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Power Seat Inoperative With Memory A45

Battery voltage is supplied at all times to the memory seat module (MSM) from the 10A DPM fuse located in the left rear fuse block. This voltage is used by the MSM for logic power and to supply battery reference voltage to the seat and lumbar adjuster switches. Battery voltage is supplied at all times to the MSM from the SEATS 30A circuit breaker located in the left rear fuse block. This voltage is used by the MSM to drive the driver seat adjuster motors, recline motor and the lumbar motors.

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

The scan tool may reference the Memory Seat Module (MSM) as the Driver Position Module.

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Driver Position Module seat switch parameters while pressing the appropriate seat switch. The reading should change between Inactive and Active.

⇒	If the reading does not change between the specified values, refer to the Seat Adjuster Switch Circuit Test.

2. If all seat switch inputs to the MSM function normal, refer to the appropriate test listed below:

•	Seat Motor Control Circuit Test

•	Recline Motor Control Circuit Test

Seat Adjuster Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the seat adjuster switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E and ground.

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

3. Install a 3A fused jumper wire between the appropriate signal circuit listed below and the B+ circuit terminal E. Verify the scan tool seat switch parameter is Active.

•	Front vertical upward switch terminal K

•	Front vertical downward switch terminal J

•	Rear vertical upward switch terminal H

•	Rear vertical downward switch terminal G

•	Horizontal forward switch terminal D

•	Horizontal rearward switch terminal C

•	Recline forward switch terminal F

•	Recline rearward switch terminal A

⇒	If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the MSM.

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

Seat Motor Control Circuit Test

1. Ignition OFF, disconnect the X1 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal B and ground.

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

3. Ignition OFF, connect the X1 harness connector at the MSM and disconnect the X1 harness connector at the seat adjuster motor assembly.
4. Connect a test lamp between the appropriate control circuits listed below:

•	Seat horizontal motor terminal 3 and terminal 6

•	Seat front vertical motor terminal 2 and terminal 5

•	Seat rear vertical motor terminal 1 and terminal 4

5. Ignition ON, command the appropriate seat motor in the Up/Down or Forward/Rearward directions with a scan tool. The test lamp should turn ON when commanding the up and down or forward and rearward states.

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

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

Recline Motor Control Circuit Test

1. Ignition OFF, disconnect the X1 harness connector at the recline motor.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, command the Recline Forward/Rearward with a scan tool. The test lamp should turn ON when commanding the forward and rearward states.

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

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.