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 Descriptor

DTC B1424: Device 1 Voltage Low

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
B+ | B1424 00 | B1424 00 | -- | --
Ground | -- | B1424 00 | -- | --

### Circuit/System Description

The theft deterrent module (TDM) monitors the battery positive (B+) circuit. If the voltage at the TDM is between 6 and 9 V, and the voltage being reported by the serial data message is greater than 9 V, DTC B1424 will set.

### Conditions for Running the DTC

• | The Ignition is in Accessory or RUN.

• | The diagnostic runs every 100 milliseconds.

### Conditions for Setting the DTC

• | Voltage at the B+ circuit is between 6 and 9 V.

• | Reported battery voltage received via serial data is valid and is greater than 9 V.

• | The above conditions have been met for 2 seconds.

### Action Taken When the DTC Sets

Security Indicator turns ON.

### Conditions for Clearing the DTC

• | A current DTC clears when the battery voltage at the TDM is greater than 9 V, or if the reported voltage by serial data is less than 9 V.

• | A history DTC clears after 100 ignition cycles, if no failures are reported by the diagnostic.

### Diagnostic Aids

A low voltage DTC in multiple modules indicates a concern in the charging system.

### Reference Information

#### Schematic Reference

Immobilizer Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Immobilizer 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 Verification

Engine running measure and record the voltage at the battery terminals. Verify that the battery voltage is 12.6-15.5 V.

If the battery voltage is not within the specified range, refer to Charging System Test.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the theft deterrent module (TDM).
2. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 Ω between the ground circuit terminal 3 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON , verify a test lamp illuminates between the B+ circuit terminal 1 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. If the circuits test normal, replace the TDM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TDM replacement, set up, and programming