For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using the diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC B1406 : PPD/SBR Malfunction

### Circuit/System Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

At this time, the SDM will establish communication with the passenger presence detection (PPD)/seat belt reminder (SBR) and the PPD/SBR will respond to the SDM by commanding the passenger air bag OFF indicator On for five seconds.

The SDM monitors the PPD/SBR status (occupied, not occupied, seated, defect) cyclically. These 4 messages should transmit every 1.2 seconds to the SDM.

### Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

### Conditions for Setting the DTC

The PPD sensor is inoperative.

### Action Taken When the DTC Sets

The SDM commands ON the AIR BAG warning lamp.

### Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Important: When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.

• | The I/P module

• | The SDM module

• | The I/P wiring harness connector

• | The SDM wiring harness connector

1. Disconnect the passenger presence detection (PPD) sensor connector.
2. Ignition ON, check for 9-16V between terminal 1 of the PPD sensor connector and ground.

⇒ | If voltage is not as specified, test circuit for an open or high resistance.

3. Ignition OFF, disconnect the sensing and diagnostic module (SDM) connector.
4. Check for 0 ohms between terminal 3 of the PPD sensor connector and ground.

⇒ | If resistance is not as specified, test circuit for an open or high resistance.

5. Check for 0 ohms between terminal 2 of the PPD sensor connector and terminal 63 of the SDM connector.

⇒ | If resistance is as specified, replace the PPD sensor.

⇒ | If resistance is not as specified, test circuit for an open or high resistance.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for SDM replacement, setup, and programming