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

### Circuit/System Description

Voltage at theft deterrent module is lower than the voltage being reported on the serial data line.

### Conditions for Running the DTC

The ignition must be ON for this code to set.

### Conditions for Setting the DTC

Module battery voltage between low voltage limits 6-9 volts for a minimum of 2 seconds and serial data voltage is greater than normal low voltage 9 volts.

### Action Taken When the DTC Sets

Security telltale ON.

### Conditions for Clearing the DTC

Module battery voltage is greater than normal voltage low limit 9 volts.

### Reference Information

#### Schematic Reference

Immobilizer Schematics

#### Connector End View Reference

Immobilizer 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

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the theft deterrent module (TDM).
2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal 3 and ground.

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

3. Measure and record the voltage at the battery terminals. Ignition ON , measure the voltage between the ignition voltage circuit terminal 2 and ground. Verify that the voltage readings do not differ more than 1 volt.

⇒ | If greater than specified value , test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the TDM.

4. Refer to Charging System Test .

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TDM replacement, setup, and programming