For 1990-2009 cars

### 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 B1405 02: Device Voltage Reference Output 2 Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
12 V Reference | B1405 02, B1825 06, B2355 06, B2365 06, B2375 06 | B1825 06, B2355 06, B2365 06, B2375 06 | -- | --
Driver Seat Front Vertical Position Sensor Signal | B2355 06 | B2355 06 | B2355 01 | --
Driver Seat Horizontal Position Sensor Signal | B2375 06 | B2375 06 | B2375 01 | --
Driver Seat Rear Vertical Position Sensor Signal | B2365 06 | B2365 06 | B2365 01 | --
Driver Seat Recline Position Sensor Signal | B1825 06 | B1825 06 | B1825 01 | --

### Circuit/System Description

The memory seat module supplies a 12 V reference to all driver seat position sensors. The module monitors this reference voltage to ensure the accuracy of the voltages being returned from the sensors. If the voltage is lower than the normal operating range, errors will occur in the memory recall operations of the seat.

### 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

The voltage reference drops below 4.8 V for more than 300 mS.

### Action Taken When the DTC Sets

All memory recall functions will be disabled.

### Conditions for Clearing the DTC

• | The current DTC will clear and set the code to history, when the fault is no longer present and the ignition is cycled 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

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Memory Seats Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector for all seat motors connected to the reference voltage circuit.
2. Ignition ON, test for B+ between any one of the 12 V reference circuit terminals listed below and ground:

• | M51D Seat horizontal motor terminal 4

• | M50D Seat front vertical motor terminal 4

• | M55D Seat rear vertical motor terminal 4

• | M56D Recline motor terminal 4

⇒ | If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K40 memory seat module.

3. Clear the diagnostic trouble code.
4. Connect the harness connector at each seat motor one at a time. Verify that DTC B1405 02 does not set each time a motor is connected.

⇒ | If the DTC sets, test or replace the seat motor.

5. If all circuits test normal, replace the K40 memory seat module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Recliner Actuator Motor Replacement

• | Front Seat Adjuster Motor Replacement

• | Control Module References for memory seat module replacement, setup, and programming