• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Lumbar Switch B+ | 1, 2 | 2 | -- | -- |
Lumbar Motor Rearward Control | 2 | 2 | -- | -- |
Lumbar Motor Forward Control | 2 | 2 | -- | -- |
Lumbar Switch Ground | -- | 2 | -- | -- |
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Power seat lumbar support without memory is completely controlled through the lumbar switch. Battery voltage is supplied at all times to the lumbar switch from the 30 A SEATS circuit breaker that is located in the rear fuse block. When the lumbar switches are in an inactive state, the switch contacts are closed to the switch ground circuit at G303.
The lumbar motor is reversible. For example, when the lumbar horizontal forward switch is pressed to move the lumbar support forward, battery voltage is applied through the switch contacts and the lumbar motor forward control circuit to the motor. The motor is grounded through the lumbar motor rearward switch contacts and the lumbar motor rearward control circuit to the motor. The motor runs in order to drive the lumbar support forward toward the occupants back until the switch is released. Moving the lumbar support rearward works similarly to moving the lumbar support forward, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.
Lumbar Support Description and Operation
• | Driver seat lumbar switch terminal H |
• | Passenger seat lumbar switch terminal E |
⇒ | If greater than the specified value, test the ground circuit for an open/high resistance. |
• | Driver seat lumbar switch terminal E |
• | Passenger seat lumbar switch terminal G |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | 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, test or replace the lumbar adjuster switch. |
⇒ | If not the specified value, replace the lumbar switch. |
⇒ | If greater than the specified range, replace the lumbar switch. |
⇒ | If greater than the specified range, replace the lumbar switch. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
B+ Lumbar Switch | 2 | 1 | -- | -- |
Lumbar Forward Switch Signal | 2 | 1 | B1830 | -- |
Lumbar Rearward Switch Signal | 2 | 1 | B1835 | -- |
Driver Seat Lumbar Motor Forward Control | -- | 1 | -- | -- |
Driver Seat Lumbar Motor Rearward Control | -- | 1 | -- | -- |
1. Lumbar Support Inoperative w/A45 2. Scan Tool Does Not Communicate with Low Speed GMLAN Device |
Battery voltage is supplied at all times to the memory seat module (MSM) from the 10A LGM/DSM fuse located in the rear fuse block. This voltage is used by the MSM for logic power and to supply battery voltage to the seat and lumbar switches. Battery voltage is supplied at all times to the MSM from the SEATS 30A circuit breaker also located in the rear fuse block. This voltage is used by the MSM to drive the driver seat adjuster motors, recline motor and the lumbar motor.
The lumbar motor is reversible. For example, when the lumbar switch is pressed to move the lumbar support forward, battery positive voltage is applied through the switch contacts and the lumbar forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery voltage through the lumbar motor forward control circuit and ground through the lumbar motor rearward control circuit to the motor. The motor runs to drive the lumbar support forward toward the occupants back until the switch is released. Moving the lumbar support rearward works similarly to moving the lumbar support 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 Seat Module.
Lumbar Support Description and Operation
Control Module References for scan tool information
⇒ | If all power seat functions do not operate, refer to Power Seat Inoperative. |
⇒ | If the reading does not change between the specified values, refer to the Lumbar Switch Circuit Test. |
⇒ | 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. |
⇒ | If not the specified value, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM. |
• | Lumbar horizontal forward terminal C |
• | Lumbar horizontal rearward terminal B |
• | Lumbar horizontal forward terminal C |
• | Lumbar horizontal rearward terminal B |
⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM. |
⇒ | 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. |
• | Lumbar horizontal forward switch terminal A |
• | Lumbar horizontal rearward switch terminal D |
⇒ | If not the specified value, replace the lumbar switch. |
• | Lumbar horizontal forward switch terminal A |
• | Lumbar horizontal rearward switch terminal D |
⇒ | If greater than the specified range, replace the lumbar switch. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for MSM replacement, setup, and programming |