DTC B144B
DTC B144B |
Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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DTC Descriptors |
DTC B144B 01
Run/Start Power Relay Circuit Short to Battery
DTC B144B 02
Run/Start Power Relay Circuit Short to Ground
DTC B144B 04
Run/Start Power Relay Circuit Open
Diagnostic Fault Information |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
Run/Crank Ignition 1 Voltage | B144B 02* | B144B 04* | B144B 01* | - |
Run/Crank Relay Coil Control | B144B 02** | 1 | 2 | - |
1. No Start 2. Engine will continue to run after the igniting is turned OFF * DTC set in keyless entry control module ** DTC Set in BCM |
Circuit/System Description |
The body control module (BCM) controls the RUN/CRNK relay through the control circuit by applying voltage to the run/crank relay coil control circuit. The ignition RUN/CRNK is energized when the ignition mode is ON or START, 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 backup power for the RUN/CRNK relay through the control circuit by applying voltage to the run/crank ignition 1 voltage circuit. This circuit is a pass-thru in the BCM and will energize the RUN/CRNK when the ignition mode is ON or START, or when a remote start is requested.
Conditions for Running the DTC |
System voltage is greater than 9 V
Conditions for Setting the DTC |
B144B 01
The run/crank output is not active and a short to battery is detected 3 consecutive times on the run/crank ignition 1 voltage circuitB144B 02 - BCM
A short to ground is detected on the run/crank relay coil control circuitB144B 02 - Keyless Entry Control Module
The run/crank output is active and a short to ground is detected 3 consecutive times on the run/crank ignition 1 voltage circuitB144B 04
The run/crank output is not active and an open is detected 20 consecutive times on the run/crank ignition 1 voltage circuitAction Taken When the DTC Sets |
B144B 01, B144B 04
No action is takenB144B 02
The RUN/CRANK relay is deactivated when the fault is set. After 100 ms, the RUN/CRANK relay will be activated. If the fault is still set, the relay will be deactivated. The RUN/CRANK relay will again be activated after 100 ms. If this also results in a fault, the relay will be deactivated until a new run/crank request is received.Conditions for Clearing the DTC |
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The current DTC will clear when the malfunction is no longer present and a run/crank request is received.
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A history DTC will clear after 40 malfunction free ignition cycles.
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Diagnostic Aids |
A short to voltage on the run/crank relay coil control will cause the engine to remain running after the ignition mode is changed to OFF.
Reference Information |
Schematic Reference
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Power Moding Schematics
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Power Distribution Schematics
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Connector End View Reference
Component Connector End Views
Description and Operation
Power Mode Description and Operation
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification |
Ignition ON, verify DTC B1330 is not set.
Circuit/System Testing |
1. |
Ignition OFF, disconnect the X2 harness connector at the K84 keyless entry control module.
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2. |
Verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
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3. |
If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the B+ circuit fuse is open, test the B+ circuit for a short to ground.
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4. |
Connect the X2 harness connector at the K84 keyless entry control module. Disconnect the X3 harness connector at the K9 BCM.
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5. |
Ignition OFF, test for less than 1 V between the ignition circuit terminal 6 and ground.
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6. |
If greater than the specified range, test the ignition circuit for a short to voltage. If the circuit tests normal, replace the K84 keyless entry control module.
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7. |
Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 6 and ground.
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8. |
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.
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9. |
Ignition OFF, Connect the X3 harness connector at the K9 BCM. Disconnect the KR74 ignition run relay.
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10. |
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 ground circuit terminal 86 and ground.
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11. |
If greater than the specified range, test the ground circuit for an open/high resistance.
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12. |
Connect a test lamp between the control circuit terminal 85 and ground.
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13. |
Cycle the ignition ON and OFF. The test lamp should turn ON and OFF when changing ignition modes.
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14. |
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.
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15. |
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.
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16. |
If all circuits test normal, test or replace the KR74 ignition run relay.
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Repair Instructions |
Perform the Diagnostic Repair Verification after completing the repair.
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Relay Replacement (Attached to Wire Harness)
Relay Replacement (Within an Electrical Center)
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Control Module References
for BCM or keyless entry control module replacement, setup, and programming
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