Volt

DTC B144B

The body control module (BCM) controls the ignition run relay through the control circuit by applying voltage to the ignition run relay coil control circuit. The ignition run relay is energised when the vehicle is in Service Mode, the vehicle is ON or when a remote start is requested. This is part of the BCM's primary function in controlling the vehicle power mode.

The keyless entry control module controls the back-up power for the ignition run relay through the control circuit by applying voltage to the ignition circuit. This circuit is a pass-thru in the BCM and will energise the ignition circuit when the vehicle is in Service Mode, the vehicle is ON or when a remote start is requested.

System voltage is greater than 9 V

B144B 01

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

B144B 02 - BCM

A short-circuit to earth is detected on the ignition run relay coil control circuit

B144B 02 - Keyless Entry Control Module

The ignition output is active and a short-circuit to earth is detected 3 consecutive times on the ignition voltage circuit

B144B 04

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

B144B 01, B144B 04

No action is taken

B144B 02

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

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

Schematic Reference

Power Moding Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Mode Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Vehicle in Service Mode, verify DTC B1330 is not set.

1. Vehicle OFF, disconnect the X2 harness connector at the K84 keyless entry control module.
2. Verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open-circuit/high resistance. If the B+ circuit fuse is open, test the B+ circuit for a short-circuit to earth.

3. Connect the X2 harness connector at the K84 keyless entry control module. Disconnect the X3 harness connector at the K9 body control module.
4. Vehicle OFF, test for less than 1 V between the ignition circuit terminal 6 and earth.

⇒	If greater than the specified range, test the ignition circuit for a short-circuit to voltage. If the circuit tests normal, replace the K84 keyless entry control module.

5. Vehicle in Service Mode, verify that a test lamp illuminates between the ignition circuit terminal 6 and earth.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K84 keyless entry control module.

6. Vehicle OFF, connect the X3 harness connector at the K9 body control module. Disconnect the KR74 ignition run relay.
7. Vehicle OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10 Ω between the ground circuit terminal 85 and ground.

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

8. Connect a test lamp between the control circuit terminal 86 and earth.
9. Cycle between Service Mode and vehicle OFF. The test lamp should turn ON and OFF when changing Service Modes and vehicle OFF.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 body control module.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 body control module.

10. If all circuits test normal, test or replace the KR74 ignition run relay.

1. Vehicle OFF, disconnect the KR74 ignition run relay.
2. Test for 70-150 Ω between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the KR74 ignition run relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than specified, replace the KR74 ignition run relay.

4. Install a 3 A fused jumper wire between relay terminal 86 and 12 V. Install a jumper wire between relay terminal 85 and earth. Measure for less than 5 Ω between terminals 87 and 30.

⇒	If greater than specified, replace the KR74 ignition run relay.

Perform the Diagnostic Repair Verification after completing the repair.