Power Seat Inoperative With Memory A45
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
72794
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Memory Seat Module B+ | 1 | 1 | -- | -- |
Seat Adjuster Switch B+ | 2 | 1 | -- | -- |
Front Vertical Up Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Front Vertical Down Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Horizontal Forward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Horizontal Rearward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Rear Vertical Down Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Rear Vertical Up Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Recline Forward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Recline Rearward Switch Signal | 2 | 1 | B1735 00, B1740 00, B1745 00, B1750 00, B1755 00, B1760 00, B1815 00, B1820 00 | -- |
Driver Seat Front Vertical Motor Down Control | 1 | 1 | -- | -- |
Driver Seat Front Vertical Motor Up Control | 1 | 1 | -- | -- |
Driver Seat Horizontal Motor Forward Control | 1 | 1 | -- | -- |
Driver Seat Horizontal Motor Rearward Control | 1 | 1 | -- | -- |
Driver Seat Rear Vertical Motor Down Control | 1 | 1 | -- | -- |
Driver Seat Rear Vertical Motor Up Control | 1 | 1 | -- | -- |
Driver Seat Recline Motor Forward Control | 1 | 1 | -- | -- |
Driver Seat Recline Motor Rearward Control | 1 | 1 | -- | -- |
Memory Seat Module Ground | -- | 2 | -- | -- |
1. Power seat inoperative 2. Scan Tool Does Not Communicate with Low Speed GMLAN Device | ||||
Circuit/System Description
Battery voltage is supplied at all times to the memory seat module (MSM) from the seat interface module (SIM) and the Power Seats circuit breaker located in the I/P fuse block. This voltage is used by the MSM for logic power and to drive the driver seat adjuster motors, recline motor and the lumbar motor.
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.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Memory Seats Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the scan tool MSM seat adjuster switch parameters listed below while operating each adjuster switch in both directions. The reading should change between Inactive and the desired direction.
- If all scan tool readings are normal, refer to the Seat Motor Control Circuit Test.
| • | Front Vertical Switch |
| • | Horizontal Switch |
| • | Rear Vertical Switch |
| • | Recline Switch |
| ⇒ | If any of the readings are Inactive or Invalid while the switch is pressed, refer to the Seat Adjuster Switch Circuit Test |
Circuit/System Testing
Seat Adjuster Switch Circuit Test
- Ignition OFF, disconnect the harness connector at the seat adjuster switch.
- Ignition ON, verify that a test lamp illuminates between the 12 V reference circuit terminal 5 and ground.
- Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and the 12 V reference circuit terminal 5. Verify the appropriate scan tool MSM seat adjuster switch parameter is Forward/Rearward or Up/Down.
- If all circuits test normal, test or replace the seat adjuster switch.
| ⇒ | If the test lamp does not illuminate, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM. |
| • | Front vertical up switch terminal 10 |
| • | Front vertical down switch terminal 7 |
| • | Rear vertical up switch terminal 9 |
| • | Rear vertical down switch terminal 8 |
| • | Horizontal forward switch terminal 3 |
| • | Horizontal rearward switch terminal 6 |
| • | Recline forward switch terminal 2 |
| • | Recline rearward switch terminal 4 |
| ⇒ | If not the specified value, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the MSM. |
Seat Motor Control Circuit Test
- Ignition OFF, disconnect the harness connector at the appropriate seat motor.
- Connect a test lamp between the appropriate control circuit terminals listed below:
- 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 all circuits test normal, test or replace the seat motor.
| • | Front vertical motor terminal 1 and terminal 5 |
| • | Rear vertical motor terminal 1 and terminal 5 |
| • | Horizontal motor terminal 1 and terminal 2 |
| • | Recline motor terminal 1 and terminal 5 |
| ⇒ | 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. |
Component Testing
Seat Adjuster Switch Test
- Ignition OFF, disconnect the harness connector at the seat adjuster switch.
- Test for infinite resistance between the 12 V reference terminal 5 and each signal terminal listed below with the switch in the open position:
- Test for less than 2 Ω between the 12 V reference terminal 5 and each signal terminal listed below with the appropriate switch in the closed position:
| • | Front vertical up switch terminal 10 |
| • | Front vertical down switch terminal 7 |
| • | Rear vertical up switch terminal 9 |
| • | Rear vertical down switch terminal 8 |
| • | Horizontal forward switch terminal 3 |
| • | Horizontal rearward switch terminal 6 |
| • | Recline forward switch terminal 2 |
| • | Recline rearward switch terminal 4 |
| ⇒ | If not the specified value, replace the seat adjuster switch. |
| • | Front vertical up switch terminal 10 |
| • | Front vertical down switch terminal 7 |
| • | Rear vertical up switch terminal 9 |
| • | Rear vertical down switch terminal 8 |
| • | Horizontal forward switch terminal 3 |
| • | Horizontal rearward switch terminal 6 |
| • | Recline forward switch terminal 2 |
| • | Recline rearward switch terminal 4 |
| ⇒ | If greater than the specified range, replace the seat adjuster switch. |
Seat Motors
- Ignition OFF, disconnect the harness connector at the appropriate seat motor.
- Install a 30 A fused jumper wire between control terminal 1 and 12 V. Momentarily install a jumper wire between control terminal 2 and ground. The seat motor should operate in the appropriate UP or FORWARD direction.
- Reverse the jumper wires. The seat motor should operate in the appropriate DOWN or REARWARD direction.
Note: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.
| ⇒ | If the motor does not perform as specified, replace the seat motor. |
| ⇒ | If the motor does not perform as specified, replace the seat motor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, programming, and setup. |
Power Seat Inoperative Without Memory A45
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 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 | -- | -- |
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 Seats 20 A Circuit Breaker located in the instrument panel 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
Connector End View Reference
Description and Operation
Power Seats System Description and Operation
Electrical Information Reference
Circuit/System Verification
Operate the seat switches for the appropriate seat directional motors listed below in both directions. The seat should move in the commanded directions.
| • | Horizontal motor (AGB, AH5, AH8, AJ6, or AQ5) |
| • | Front vertical motor (AGB, AH5, AH6, AH7, AH8, AJ6, or AQ5) |
| • | Rear vertical motor (AGB, AH5, AH6, AH7, AH8, AJ6, or AQ5) |
| • | Recline motor (AGB, AH5, or AH8) |
| ⇒ | If the power seat is inoperative in all directions, refer to the Seat Adjuster Switch 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
- Disconnect the harness connector at the seat adjuster switch.
- Test for less than 5 Ω between the ground circuit terminal 2 and ground.
- Verify that a test lamp illuminates between the appropriate B+ circuit terminal 1 and ground.
- If all circuits test normal, test or replace the seat adjuster switch.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
Seat Adjuster Motor Circuit Test
- Ignition OFF, disconnect the harness connector at the appropriate seat motor.
- Connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
- 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 all circuits tests normal, test or replace the seat motor.
| ⇒ | 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. |
Component Testing
Seat Adjuster Switch Test
- Ignition OFF, disconnect the harness connector at the seat adjuster switch.
- Test for infinite resistance between the B+ terminal 1 and each control terminal listed below with the switch in the open position.
- Test for less than 1 Ω between the B+ terminal 1 and each control terminal listed below with the appropriate switch in the closed position.
- Test for less than 1 Ω between the ground terminal 2 and each control terminal listed below with the switch in the open position.
| • | Seat front up terminal 3 |
| • | Seat front down terminal 4 |
| • | Seat rear up terminal 5 |
| • | Seat rear down terminal 6 |
| • | Horizontal forward terminal 7 |
| • | Horizontal rearward terminal 8 |
| ⇒ | If not the specified value, replace the seat adjuster switch. |
| • | Seat front up terminal 3 |
| • | Seat front down terminal 4 |
| • | Seat rear up terminal 5 |
| • | Seat rear down terminal 6 |
| • | Horizontal forward terminal 7 |
| • | Horizontal rearward terminal 8 |
| ⇒ | If greater than the specified range, replace the seat adjuster switch. |
| • | Seat front up terminal 3 |
| • | Seat front down terminal 4 |
| • | Seat rear up terminal 5 |
| • | Seat rear down terminal 6 |
| • | Horizontal forward terminal 7 |
| • | Horizontal rearward terminal 8 |
| ⇒ | If greater than the specified range, replace the seat adjuster switch. |
Seat Motors
- Ignition OFF, disconnect the harness connector at the appropriate seat motor.
- Install a 30 A fused jumper wire between control terminal 1 and 12 V. Momentarily install a jumper wire between control terminal 2 and ground. The seat motor should operate in the appropriate UP or FORWARD direction.
- Reverse the jumper wires. The seat motor should operate in the appropriate DOWN or REARWARD direction.
Note: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.
| ⇒ | If the motor does not perform as specified, replace the seat motor. |
| ⇒ | If the motor does not perform as specified, replace the seat motor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
