DTC B144A
Diagnostic Instructions
DTC Descriptor
DTC B144A 02: RUN Power Relay Circuit Short to Ground
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Ignition 1 Relay Control
| B144A 02
| 1
| 2
| --
|
1. No Start.
2. Vehicle will start and continue to run after the ignition key is removed.
|
Circuit/System Description
The body control module (BCM) controls the ignition 1 relay through the control circuit by applying voltage to the circuit. The ignition 1 relay is energised when the ignition switch is in ON or START, or when a remote start is requested.
Conditions for Running the DTC
| • | The system voltage is between 9–16 V. |
| • | The DTC can only run when the output is activated. |
Conditions for Setting the DTC
The BCM detects a short to ground in the ignition 1 relay control circuit.
Action Taken When the DTC Sets
The module output driver will be shut down and not supply voltage to the ignition 1 relay control circuit.
Conditions for Clearing the DTC
| • | The current DTC will clear when the module request for the output is removed or the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction. |
Diagnostic Aids
Short to voltage in the ignition 1 relay control circuit will cause the malfunction indicator lamp (MIL) to illuminate with the ignition key OFF, and the engine will remain running if started and the ignition key is removed.
Reference Information
Schematic Reference
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
Circuit/System Testing
- Ignition OFF, disconnect the KR73 ignition main relay.
- Ignition 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 relay ground circuit and ground.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
- Ignition ON, verify that a test lamp illuminates between the relay B+ circuit and ground.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
- Connect a test lamp between the relay control circuit and ground.
- Cycle the ignition ON and OFF. The test lamp should turn ON and OFF when changing S39 ignition switch positions.
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. |
| ⇒ | 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 BCM. |
- If all circuits test normal, test or replace the KR73 ignition main relay.
Component Testing
- Ignition OFF, disconnect the KR73 ignition main relay.
- Test for 70-150 Ω between terminals 85 and 86.
| ⇒ | If the resistance is not within the specified range, replace the KR73 ignition main relay. |
- Test for infinite resistance between the following terminals:
| ⇒ | If less than specified, replace the KR73 ignition main relay. |
- Install a 3 A fused jumper wire between relay terminal 86 and 12 V. Install a jumper wire between relay terminal 85and ground. Measure for less than 5 Ω between terminals 87 and 30.
| ⇒ | If greater than specified, replace the KR73 ignition main relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
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