PRE-RELEASE
DTC B3889
| DTC B3889 |
| 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
has overviews of all diagnostic categories.
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| DTC Descriptors |
DTC B3889 02
Trailer Brake Lamps Circuit Short to Ground
DTC B3889 04
Trailer Brake Lamps Circuit Open
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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Trailer Brake Lamps Control
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3889 02
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3889 04
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| Circuit/System Description |
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal to the body control module (BCM). The BCM sends this message to the trailer lighting converter. The trailer lighting converter then applies a voltage to the trailer brake lamp through there supply circuit.
| Conditions for Running the DTC |
B3889 02 or B3889 04
The appropriate trailer brake lamp signal is active.| Conditions for Setting the DTC |
B3889 02
The trailer lighting converter detects a short to ground on the control circuit.B3889 04
The trailer lighting converter detects an open control circuit.| Conditions for Clearing the DTC |
The condition for setting the DTC is not longer present.
| Action Taken When the DTC Sets |
The appropriate trailer brake lamp is inoperative.
| Reference Information |
Schematic Reference
Trailer Connector/Provision Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Exterior Lighting Systems 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 information on diagnostic tools
| Circuit/System Verification |
Ignition ON, perform the Trailer Brake Lamps test. The trailer brake lamps should be ON/OFF.
| Circuit/System Testing |
| 1. |
Ignition OFF, test for less than 5 Ω between the X88 Trailer Connector terminal 3, 11, 13 and ground.
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| 2. |
If greater than the specified value, test the appropriate ground circuit for an open circuit/high resistance.
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| 3. |
Connect a test lamp between the X88 Trailer Connector terminal 6 and ground.
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| 4. |
Command the Trailer Brake Lamps Active/Inactive test with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
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| 5. |
If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K68 Trailer Lighting Control Module.
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| 6. |
If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K68 Trailer Lighting Control Module.
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| 7. |
If all the circuits test normal, test the brake lamp circuit at the trailer.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for trailer lighting converter replacement, setup and programming
