B3920
DTC B3920
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B3920 00
-
Driver Seat Motors Group 1 Common Circuit Malfunction
DTC B3920 01
-
Driver Seat Motors Group 1 Common Circuit Short to Battery
DTC B3920 02
-
Driver Seat Motors Group 1 Common Circuit Short to Ground
DTC B3920 42
-
Driver Seat Motors Group 1 Common Circuit Calibration Not Programmed
DTC B3920 0B
-
Driver Seat Motors Group 1 Common Circuit High Current
Diagnostic Fault Information
Circuit/System Description
The seat memory control module controls the seat motors via half bridges that are connected to power rails internal to the module. The seat memory control module connects all of the motor control circuits on each power rail to a common reference point whenever they are not in operation. This reference point is biased to approximately 2.5 V. The seat memory control module checks to see if this reference voltage is shorted to ground or battery before enabling any seat motor.
When a power seat switch is pressed or when a memory recall is requested, each seat motor receives battery voltage and ground from the seat memory control module via the motor control circuits. All motors are reversible, so the direction the motor rotates depends on which control circuit voltage is applied and which control circuit ground is applied. When the switch 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 opposite direction.
Conditions for Running the DTC
* DTC B1325 must not be present.
* Module battery voltage must be between 9-16 V.
Conditions for Setting the DTC
B3920 00
Current out of the module does not match the current returning to the module from 1.5-5 A.
B3920 01
The voltage on any power rail 1 motor control circuit exceeds 2.78 V for 100 ms.
B3920 02
The voltage on any power rail 1 motor control circuit is below 1.47 V for 100 ms.
B3920 42
This DTC will set if the module calibration is not programmed.
B3920 0B
The differential current measured through the high and low side of the power rail is within tolerance of each other, but the absolute current or an over-current has exceeded the maximum value.
Action Taken When the DTC Sets
The seat memory control module will not allow operation of any motor on the power rail for which the DTC was set.
Conditions for Clearing the DTC
* The current DTC clears when the fault is no longer present and the power mode changes to OFF then back to ACC or RUN.
* The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.
Reference Information
Schematic Reference
Driver Seat Schematics Driver Seat Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Memory Seats Description and Operation Memory Seats
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
B3920 01 or B3920 02
1. Ignition OFF, disconnect the X4 and X5 harness connectors at the K40 seat memory control module.
2. Test for infinite resistance between the control circuit terminals listed below and ground:
* M50D front vertical motor up control terminal 7 X4
* M50D front vertical motor down control terminal 8 X4
* M55D rear vertical motor up control terminal 4 X5
* M55D rear vertical motor down control terminal 3 X5
* M51D horizontal motor forward control terminal 2 X5
* M51D horizontal motor rearward control terminal 1 X5
* M56D recline motor forward control terminal 5 X5
* M56D recline motor rearward control terminal 6 X5
• If less than infinite resistance
Repair the short to ground on the circuit.
• If infinite resistance
3. Ignition ON.
4. Test for less than 1 V between the control circuit terminals listed below and ground:
* M50D front vertical motor up control terminal 7 X4
* M50D front vertical motor down control terminal 8 X4
* M55D rear vertical motor up control terminal 4 X5
* M55D rear vertical motor down control terminal 3 X5
* M51D horizontal motor forward control terminal 2 X5
* M51D horizontal motor rearward control terminal 1 X5
* M56D recline motor forward control terminal 5 X5
* M56D recline motor rearward control terminal 6 X5
• If 1 V or greater
Repair the short to voltage on the circuit.
• If less than 1 V
5. Replace the K40 seat memory control module.
B3920 00 or B3920 0B
1. Ignition ON.
2. Clear the current and history DTC.
3. Determine which motor set this DTC by operating the driver seat motors listed below one at a time in both directions. Check for the DTC to set between each motor test.
* M50D seat front vertical motor
* M55D seat rear vertical motor
* M51D seat horizontal motor
* M56D seat back recline motor
4. Ignition OFF, disconnect the harness connector at the seat motor for which the DTC set, ignition ON.
5. Clear the DTC.
6. Verify that DTC B3920 00 or B3920 0B does not set while operating the seat motor adjuster switch in both directions.
• If DTC B3920 00 or B3920 0B sets
1. Test for infinite resistance between control circuit terminal 1 and control circuit terminal 5.
• If less than infinite resistance, repair the short between the circuits.
• If infinite resistance
2. Test for less than 2 ohms between the control circuit terminals listed below end to end:
- Terminal 1
- Terminal 5
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the seat motor.
• If DTC B3920 00 or B3920 0B does not set
7. Replace the seat motor.
B3920 42
1. Ignition ON.
2. Verify the DTC is not set.
• If the DTC is set
Replace the K40 seat memory control module.
• If the DTC is not set
3. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Front Seat Tilt Adjuster Actuator Replacement Front Seat Tilt Adjuster Actuator Replacement
* Front Seat Adjuster Actuator Replacement Front Seat Adjuster Actuator Replacement
* Driver Seat Outer Adjuster Rear Vertical Actuator Replacement Driver Seat Outer Adjuster Rear Vertical Actuator Replacement
* Driver or Passenger Seat Recliner Actuator Replacement Driver or Passenger Seat Recliner Actuator Replacement
* Control Module References Control Module References for seat memory control module replacement, programming and setup