Circuit Description
The Body Control Module (BCM) provides the steering column control function which allows the column to be electronically locked or unlocked. The BCM provides three outputs, steering column lock, steering column unlock, and a steering column lock relay control. The BCM can apply a ground or battery output on the steering column lock or steering column unlock depending on the desired steering column lock motor position. The BCM uses the feedback switch in order to monitor the motor position and determine if the commanded position was accomplished.
The BCM controls the position of the steering column lock motor based on the following input information:
| • | Ignition position |
| • | Key IN ignition status |
| • | Key OUT of Ignition status |
| • | Steering column lock feedback switch |
| • | PASS-Key® system |
| • | PCM password information |
| • | System voltage |
The BCM also monitors its circuitry for the steering column lock circuit. If the BCM detects a malfunction present a DTC will set.
Conditions for Setting the DTC
| • | The BCM detects an internal malfunction, an open or a short to ground, in the column lock drive A circuit. |
| • | There is an open in the BCM battery positive voltage circuit from BCM2 fuse. |
| • | The condition must be present for 100 ms. |
Action Taken When the DTC Sets
| • | Stores a DTC B2587 in the BCM memory. |
| • | The PCM may disable fuel if vehicle speed is detected over 2.4 km/h (1.5 mph). |
| • | Sends a message to the IPC to display the SERVICE COLUMN LOCK message. |
Conditions for Clearing the DTC
| • | The BCM no longer detects an internal malfunction, an open or a short to ground, in the steering column lock circuit. |
| • | Supply voltage is available on the battery positive voltage circuit from BCM2 fuse. |
| • | A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Use a scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction: |
| - | There is an intermittent open in BCM battery positive voltage circuit from BCM2 fuse. |
| - | The steering column lock or unlock circuits are shorted together or to ground. |
| • | A short to ground in the BCM battery positive voltage circuit will cause BCM2 fuse to open. The BCM receives supply voltage for the steering column lock motor through the BCM battery positive voltage circuit. If the BCM is unable to supply voltage to the steering column lock motor through the BCM battery positive voltage circuit, the BCM will set a DTC B2587. |
| • | Disconnecting or opening the steering column lock feedback circuit with the ignition in the ON position will cause the BCM to enter a Fail Enable Standby mode. The steering column will remain inoperative until the Fail Enable Standby mode is cleared. To clear this mode, disconnect the BCM1 & IPC fuse in the I/P fuse block for 15 seconds. |
| • | The BCM1 fuse will become open if the steering column lock motor or the steering column lock or unlock circuits are shorted together or to ground. |
| • | If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Tests for an open in the BCM2 fuse. BCM2 fuse supplies power to the BCM to operate the steering column lock motor.
-
Tests for an open in the BCM battery positive voltage circuit at the BCM.
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Tests for an open or short to ground in the BCM battery positive voltage circuit between the steering column lock relay and the I/P fuse block.
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Tests for an open or short to ground in the steering column lock or unlock circuit. If steering column lock or unlock circuit is shorted to ground the BCM2 fuse will open.
-
When the BCM is replaced, use a scan tool to perform the BCM RPO Reprogram procedure.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Column/Ignition Lock Schematics | |||
1 | Did you perform the Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Steering Wheel and Column - Tilt |
Test BCM2 fuse for an open. Did you find the fuse open? | Go to Step 4 | Go to Step 3 | |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 4 | |
Test the BCM battery positive voltage circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 | |
Test the steering column lock and unlock circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | |
6 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
7 | Replace the steering column lock motor. Refer to Electronic Column Lock Module Replacement - On Vehicle in Steering. Did you complete the replacement? | Go to Step 9 | -- |
|
Important: Perform the BCM RPO Reprogram procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System. Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 9 | -- | |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
