DTC B1451
Diagnostic Instructions
DTC Descriptors
DTC B1451 01: Accessory Power Circuit Short-Circuit to Battery
DTC B1451 02: Accessory Power Circuit Short-Circuit to Earth
DTC B1451 04: Accessory Power Circuit Open
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Ignition
| B1451 02
| B1451 04
| B1451 01
| --
|
Circuit/System Description
The keyless entry control module provides back-up controls for the ignition power circuit, through the control circuit, by applying voltage to the circuit. The ignition power circuit is energised when the vehicle power mode is in Vehicle ON or Vehicle in Service Mode.
Conditions for Running the DTC
B1451 01, B1451 04
| • | Vehicle power mode is Vehicle OFF |
| • | DTC B1451 not already set |
| • | System voltage between 6 and 16 V |
B1451 02
| • | Vehicle power mode is Vehicle ON or Vehicle in Service Mode |
| • | The DTC is only run when the output is active |
| • | DTC B1451 is not already set |
| • | System voltage between 6 and 16 V |
Conditions for Setting the DTC
B1451 01
Ignition output is not active and a short-circuit to battery is detected 3 consecutive times.
B1451 02
Ignition output is active and a short-cricuit to earth is detected 3 consecutive times.
B1451 04
Ignition output is not active and an open-circuit is detected 20 consecutive times.
Action Taken When the DTC Sets
B1451 02
The ignition output is deactivated when a short-circuit to earth is detected. After 100 ms the output is activated again. This happens 3 times and then the output is deactivated until a new Vehicle ON or Vehicle in Service Mode request is received.
B1451 01, B1451 04
No action is taken.
Conditions for Clearing the DTC
| • | The current DTC will clear when the malfunction is no longer present during a DTC check. |
| • | A history DTC clears when the module power mode cycle counter reaches the reset threshold of 40, without a repeat of the malfunction. |
Diagnostic Aids
| • | A short-circuit to voltage in the ignition control circuit will keep the vehicle modules awake, which can drain the vehicle's battery. |
| • | A short-circuit to earth in the extension of this circuit through the body control module can back feed to the keyless entry control module. Check for a short-circuit to earth on the ignition circuit on the other side of the ignition pass thru, in the body control module, before replacing the body control module. |
Reference Information
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
Circuit/System Verification
Verify DTC B1330 is not set.
| ⇒ | If the DTC is set, refer to DTC B1325, B1330, B1517, C0800, C0899, C0900, C12E1, C12E2, P0562, P0563, P1A0C, P1A0D, or P1EFC . |
Circuit/System Testing
- Vehicle OFF, disconnect the X2 harness connector at the K84 keyless entry control module.
- Verify that a test lamp illuminates between B+ circuit terminal 5 and ground.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
- Vehicle OFF, reconnect the X2 harness connector at the K84 keyless entry control module and disconnect the X3 harness connector at the K9 body control module.
- Vehicle OFF, test for less than 1 V between the ignition circuit terminal 5 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. |
- Vehicle in Service Mode, verify that a test lamp illuminates between the ignition circuit terminal 5 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. |
- If all circuits test normal, replace the K9 body control module.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for the appropriate control module replacement, programming and set-up
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