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 B1442: Device Ignition OFF, RUN, and CRANK Circuit Low
DTC B1443: Device Ignition OFF, RUN, and CRANK Circuit High

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Off/Run/Crank voltage (ignition switch output) | B1442 | B1442 | B1443 | --
5-V reference | B1442 | B1442 | B1443 | --

### Circuit/System Description

The body control module (BCM) monitors the ignition inputs Ignition Off/Run/Crank, Ignition 1 Run/Crank and the Ignition Accessory signals supplied from the ignition switch. The BCM uses the sequence that the signals appear, their voltage levels and the engine run flag (ERF) status to determine the power mode. Battery voltage is supplied to the ignition switch by a fuse in the underhood fuse block. In addition, the BCM supplies the ignition switch a 5-V reference signal that the ignition switch uses for the output to the BCM on the off/run/crank voltage circuit. The off/run/crank voltage circuit supplies voltage to the BCM for theft purposes.

### Conditions for Running the DTC

B+ is between 9-16 V.

### Conditions for Setting the DTC

#### B1442

The BCM detects that the Off/Run/Crank signal is open or shorted to ground.

#### B1443

The BCM detects that the Off/Run/Crank signal is shorted to voltage.

### Action Taken when the DTC Sets

• | The BCM stores DTC B1442 or B1443 in memory.

• | The BCM determines a fail-safe power mode dependent on the last valid power mode detected and the state of the ERF.

### Conditions for Clearing the DTC

• | A current DTC clears when the malfunction is no longer present.

• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

### Reference Information

#### Schematic Reference

Power Distribution Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Power Mode 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

With a scan tool, observe the Ignition Accessory parameter and compare the parameter to the Correct Ignition Switch Inputs table with the corresponding ignition key position. The Correct Ignition Switch Inputs table illustrates the correct state of these input parameters (circuits) in correspondence to the ignition switch position.

#### PMM Power Mode Parameters

Ignition Switch Position | Ignition Accessory (Terminal 1) | Ignition 1 Run/Crank (Terminal 3) | Ignition Off/Run/Crank (Terminal 4)
--- | --- | --- | ---
OFF | Inactive | Inactive | Active
ACC | Active | Inactive | Inactive
ON | Active | Active | Active
START | Inactive | Active | Active

### Circuit/System Testing

Important: The ignition switch component test must be preformed before proceeding with this test to verify the integrity of the switch.

1. Perform the ignition switch component test. The test should pass.

⇒ | If the ignition switch fails, replace the ignition switch.

2. Ignition OFF, disconnect the X2 harness connector at the BCM. Connect the harness connector at the ignition switch.
3. Verify that a test lamp does not illuminate between ground and the off/run/crank voltage circuit terminal A14.

⇒ | If the test lamp illuminates, test the following ignition switch circuits for a short to voltage:

• | 5-V reference

• | Of/run/crank voltage

4. Verify that a test lamp does not illuminate between B+ and the off/run/crank voltage circuit terminal A14.

⇒ | If the test lamp illuminates, test the following ignition switch circuits for a short to ground:

• | 5-V reference

• | Of/run/crank voltage

5. Ignition ON, test for less than 1.0 Ω on the off/run/crank voltage circuit between BCM connector terminal A14 and terminal A42.

⇒ | If greater than the specified range, test the following ignition switch circuits for open/high resistance.

• | 5-V reference

• | Of/run/crank voltage

6. If all circuits test normal, replace the BCM.

### Component Testing

#### Ignition Switch

1. Ignition OFF, disconnect the harness connector at the ignition switch.
2. Using the Resistance Test table below, check the resistance between the terminals of the ignition switch listed in each switch position.

#### Resistance Test

Ignition Switch Position | Terminals 1 and 2 | Terminals 2 and 3 | Terminals 2 and 4 | Terminals 2 and 5 | Terminals 4 and 5
--- | --- | --- | --- | --- | ---
Off Key Out | Infinite | Infinite | Infinite | Infinite | Infinite
Off Key IN | Infinite | Infinite | < 5.0 Ω | Infinite | Infinite
Accessory | < 5.0 Ω | Infinite | Infinite | Infinite | Infinite
Run | < 5.0 Ω | < 5.0 Ω | Infinite | Infinite | < 5.0 Ω
Start | Infinite | < 5.0 Ω | Infinite | Infinite | 250 Ω-10 kΩ

⇒ | If any reading is not as specified, replace the ignition switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• | Ignition and Start Switch Replacement

• | Control Module References for BCM replacement, setup, and programming