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. |
DTC Descriptors
DTC B3920 01: Group 1 Seat Motors Common Circuit Short to BatteryDTC B3920 02: Group 1 Seat Motors Common Circuit Short to Ground
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Driver Seat Front Vertical Motor Down Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2355 5A |
Driver Seat Front Vertical Motor Up Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2355 5A |
Driver Seat Rear Vertical Motor Down Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2365 5A |
Driver Seat Rear Vertical Motor Up Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2365 5A |
Driver Seat Horizontal Motor Forward Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2375 5A |
Driver Seat Horizontal Motor Rearward Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B2375 5A |
Driver Seat Recline Motor Forward Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B1825 5A |
Driver Seat Recline Motor Rearward Control | B3920 02 | B1335 00, B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B1825 5A |
Driver Seat Lumbar Motor Up Control | B3920 02 | B1335 00, B1335 0B | 2 | B3920 01 | B1335 42, B1335 4B, B1860 5A |
Driver Seat Lumbar Motor Down Control | B3920 02 | B1335 00, B1335 0B | 2 | B3920 01 | B1335 42, B1335 4B, B1860 5A |
Driver Seat Lumbar Motor Forward Control | B3920 02 | B1335 00, B1335 0B | 2 | B3920 01 | B1335 42, B1335 4B, B1850 5A |
Driver Seat Lumbar Motor Rearward Control | B3920 02 | B1335 00, B1335 0B | 2 | B3920 01 | B1335 42, B1335 4B, B1850 5A |
1. Power seat motor inoperative 2. Lumbar motor inoperative | |||||
Circuit/System Description
The memory seat module (MSM) controls the seat, lumbar, and adjustable pedal motors via half bridges that are connected to a common power rail internal to the module. When a power seat switch is pressed or when a memory recall is requested, each seat or lumbar motor receives battery voltage and ground from the MSM via the motor control circuits. All seat and lumbar motors are reversible, so the direction the seat moves depends on which control circuit voltage is applied and which control circuit the ground is applied. For example, to move the seat in the forward direction, the module applies voltage to the seat horizontal motor forward control circuit, and ground to the seat horizontal motor rearward control circuit. When the seat is operated in the opposite direction, the module reverses the polarity and applies voltage and ground to the opposite circuits to move the seat in the rearward direction. All seat and lumbar motors are powered this way.
Conditions for Running the DTC
The MSM must be powered.
Conditions for Setting the DTC
B3920 01
The voltage on any power rail 1 motor control circuit exceeds 2.78 volts for 100 ms.
B3920 02
The voltage on any power rail 1 motor control circuit is below 1.47 volts for 100 ms.
Action Taken When the DTC Sets
The MSM disables all motors in the group for which the DTC was set.
Conditions for Clearing the DTC
| • | The current DTC clears and sets to history when the reference voltage is between 1.47 volts and 2.5 volts for 3 seconds and the power mode changes to OFF then back to ACC or RUN. |
| • | The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred. |
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 Testing
- Ignition OFF, disconnect the X1 harness connector at the MSM.
- Ignition ON, verify that a test lamp does not illuminate between control circuits listed below and ground:
- Test for infinite resistance between the control circuits listed below and ground:
- Ignition OFF, disconnect the X4 harness connector at the MSM.
- Ignition ON, verify that a test lamp does not illuminate between control circuits listed below and ground:
- Test for infinite resistance between the control circuits listed below and ground:
- If all circuits test normal, replace the MSM.
| • | Front vertical motor terminal 12 |
| • | Front vertical motor terminal 13 |
| • | Rear vertical motor terminal 15 |
| • | Rear vertical motor terminal 16 |
| • | Seat horizontal motor terminal 9 |
| • | Seat horizontal motor terminal 10 |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| • | Front vertical motor terminal 12 |
| • | Front vertical motor terminal 13 |
| • | Rear vertical motor terminal 15 |
| • | Rear vertical motor terminal 16 |
| • | Seat horizontal motor terminal 9 |
| • | Seat horizontal motor terminal 10 |
| ⇒ | If not the specified value, test the control circuit for a short to ground. |
| • | Lumbar vertical motor terminal 1 |
| • | Lumbar vertical motor terminal 2 |
| • | Lumbar horizontal motor terminal 12 |
| • | Lumbar horizontal motor terminal 13 |
| • | Seat recline motor terminal 15 |
| • | Seat recline motor terminal 16 |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| • | Lumbar vertical motor terminal 1 |
| • | Lumbar vertical motor terminal 2 |
| • | Lumbar horizontal motor terminal 12 |
| • | Lumbar horizontal motor terminal 13 |
| • | Seat recline motor terminal 15 |
| • | Seat recline motor terminal 16 |
| ⇒ | If not the specified value, test the control circuit for a short to ground. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for the MSM replacement, programming and setup |
