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B144B




DTC B144B

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B144B 01
- Run/Crank Power Relay Circuit Short to Battery

DTC B144B 02
- Run/Crank Power Relay Circuit Short to Ground

DTC B144B 04
- Run/Crank Power Relay Circuit Open

Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) controls the ignition main relay through the control circuit by applying voltage to the run/crank relay control circuit. The ignition main relay is energized when the ignition switch is in the ON mode or the Ignition CRANK mode.

Conditions for Running the DTC

System voltage greater than 9 V.

Conditions for Setting the DTC

B144B 01

The ignition output is not active and a short to battery is detected 3 consecutive times on the ignition voltage circuit.

B144B 02

A short to ground is detected on the ignition main relay coil control circuit.

B144B 04

The ignition output is not active and an open is detected 20 consecutive times on the ignition voltage circuit.

Action Taken When the DTC Sets

B144B 01, B144B 04

No action is taken.

B144B 02

The ignition main relay is deactivated when the fault is set. After 100 ms, the ignition main relay will be activated. If the fault is still set, the relay will be deactivated. The ignition main relay will again be activated after 100 ms. If this also results in a fault, the ignition main relay will be deactivated until a new ignition request is received.

Conditions for Clearing the DTC

* The current DTC will clear when the malfunction is no longer present and an ignition request is received.

* A history DTC will clear after 40 malfunction-free ignition cycles.

Diagnostic Aids

A short to voltage on the ignition main relay coil control will cause the engine to remain running after the mode is changed to OFF.

Reference Information

Schematic Reference

Power Moding Schematics Power Moding Schematics

Power Distribution Schematics Power Distribution Schematics

Connector End View Reference

Component Connector End Views Outside Rearview Mirror - Driver

Description and Operation

Power Mode Description and Operation Power Mode

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify the KR73 Ignition Main Relay turns ON and OFF when switching the ignition between ON and OFF.

• If the KR73 Ignition Main Relay does not turn ON and OFF
Refer to Circuit/System Testing.

• If the KR73 Ignition Main Relay turns ON and OFF

3. All OK.

Circuit/System Testing

Without BTM

1. Ignition OFF, disconnect the KR73 Ignition Main Relay, ignition ON.

2. Connect a test lamp between the control circuit terminal 86 and ground.

3. Verify the test lamp turns ON and OFF when switching the ignition between ON and OFF.

• If the test lamp is always OFF

1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.

2. Test for less than 1 V between the control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V, replace the K9 Body Control Module.

• If the test lamp turns ON and OFF

4. Test or replace the KR73 Ignition Main Relay.

With BTM

1. Ignition ON, disconnect the X2 harness connector at the K84 Keyless Entry Control Module.

2. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF, remove the test lamp.

2. Test for less than 2 ohms in the B+ circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is good and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF, remove the test lamp.

2. Test for infinite resistance between the ignition circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the K84 Keyless Entry Control Module.

• If the test lamp illuminates

3. Ignition OFF, connect the X2 harness connector at the K84 Keyless Entry Control Module and disconnect the X3 harness connector at the K9 Body Control Module.

4. Test for less than 1 V between the ignition circuit terminal 6 and ground.

• If 1 V or greater
Repair the short to voltage on the circuit.

• If less than 1 V

5. Ignition ON.

6. Verify a test lamp illuminates between the ignition circuit terminal 6 and ground.

• If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.

2. Test for infinite resistance between the ignition circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance.

3. Test for less than 2 ohms in the ignition circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K84 Keyless Entry Control Module.

• If the test lamp illuminates

7. Ignition OFF, remove the test lamp, connect the X3 harness connector at the K9 Body Control Module.

8. Ignition OFF and all vehicle systems OFF, disconnect the KR73 Ignition Main Relay. It may take up to 2 minutes for all vehicle systems to power down.

9. Test for less than 10 ohms between the ground circuit terminal 86 and ground.

• If 10 ohms or greater

1. Ignition OFF.

2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, repair the open/high resistance in the ground connection.

• If less than 10 ohms

10. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.

11. Verify the test lamp turns ON and OFF when switching the ignition between ON and OFF.

• If the test lamp is always OFF

1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance.

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.

2. Test for less than 1 V between the control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V, replace the K9 Body Control Module.

• If the test lamp turns ON and OFF

12. Test or replace the KR73 Ignition Main Relay.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)

* Control Module References Control Module References for Body Control Module or Keyless Entry Control Module replacement, programming and setup

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