Circuit Description
The body control module (BCM) controls the left front door lock motor. The BCM applies power to the driver's door unlock feed circuit. This energizes the door lock motor in order to unlock the door lock.
Conditions for Running the DTC
The BCM must not be commanding the door lock motor to unlock the door lock.
Conditions for Setting the DTC
| • | The BCM detects a short to battery in the driver's door unlock feed circuit when the BCM is not trying to energize the door lock motor to unlock the door lock. |
| • | The condition above must be present for more than 0.3 seconds. |
Action Taken When the DTC Sets
The BCM stores DTC B3128 in memory.
Conditions for Clearing the DTC
| • | A short to battery in the driver's door unlock feed circuit is no longer detected by the BCM. |
| • | A history DTC B3128 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | A scan tool may be used in order to clear the DTC. |
Diagnostic Aids
| • | If the DTC B3128 is a history DTC, the fault may be intermittent. Refer to Intermittents and Poor Connections. |
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent short to battery in the driver's door unlock feed circuit |
| - | The left front door lock motor is shorted to battery internally. |
| - | The BCM is shorted to battery internally. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
Listen for an audible noise when the left front door lock motor is commanded to unlock . Command the door lock motor to lock and unlock. Repeat the commands as necessary.
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This step verifies that the body control module is providing voltage to the left front door lock motor.
-
This step tests for an open in the ground circuit to the left front door lock motor.
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This step tests if voltage is constantly being applied to the left front door lock motor.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Power Door Locks System Check? | -- | Go to Step 2 | |
Does the left front door lock motor unlock when commanded? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp flash when the door lock motor is commanded to unlock? | -- | Go to Step 4 | Go to Step 5 | |
Does the test lamp flash when commanded? | -- | Go to Step 8 | Go to Step 10 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the unlock control circuit of the left front door lock motor 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 13 | Go to Step 9 |
7 | Test the unlock control circuit of the left front door lock motor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the left front door lock motor. 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 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the body control module. 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 13 | Go to Step 12 |
10 | Repair the ground circuit of the left front door lock motor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the left front door lock motor. Refer to Front Side Door Lock Replacement . Did you complete the repair? | -- | Go to Step 13 | -- |
12 |
Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
