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 LowDTC 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
Connector End View Reference
Description and Operation
Power Mode Description and Operation
Electrical Information Reference
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.
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
- Perform the ignition switch component test. The test should pass.
- Ignition OFF, disconnect the X2 harness connector at the BCM. Connect the harness connector at the ignition switch.
- Verify that a test lamp does not illuminate between ground and the off/run/crank voltage circuit terminal A14.
- Verify that a test lamp does not illuminate between B+ and the off/run/crank voltage circuit terminal A14.
- 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 all circuits test normal, replace the BCM.
Important: The ignition switch component test must be preformed before proceeding with this test to verify the integrity of the switch.
| ⇒ | If the ignition switch fails, replace the ignition switch. |
| ⇒ | If the test lamp illuminates, test the following ignition switch circuits for a short to voltage: |
| • | 5-V reference |
| • | Of/run/crank voltage |
| ⇒ | If the test lamp illuminates, test the following ignition switch circuits for a short to ground: |
| • | 5-V reference |
| • | Of/run/crank voltage |
| ⇒ | If greater than the specified range, test the following ignition switch circuits for open/high resistance. |
| • | 5-V reference |
| • | Of/run/crank voltage |
Component Testing
Ignition Switch
- Ignition OFF, disconnect the harness connector at the ignition switch.
- Using the Resistance Test table below, check the resistance between the terminals of the ignition switch listed in each switch position.
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.
| • | Control Module References for BCM replacement, setup, and programming |
