DTC B3887 or B3888 (With U4G)
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DTC B3887 or B3888 (With U4G)
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DTC B3887 02
Trailer Left Turn Signal Circuit Short to Ground
DTC B3887 04
Trailer Left Turn Signal Circuit Open
DTC B3888 02
Trailer Right Turn Signal Circuit Short to Ground
DTC B3888 04
Trailer Right Turn Signal Circuit Open
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Trailer Left Turn Signal
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B3887 02
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B3887 04
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1
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-
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Trailer Right Turn Signal
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B3888 02
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B3888 04
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2
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-
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1. Left Trailer Turn Signal Lamp Always On
2. Right Trailer Turn Signal Lamp Always On
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Circuit/System Description
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The trailer brake control module will receive a serial data message from the BCM indicating that the vehicle left turn signal lamp or the right turn signal lamp has been activated. The trailer brake control module will then apply a pulsating voltage to the appropriate trailer turn signal lamps through their respective voltage supply circuits.
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Conditions for Running the DTC
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When the trailer left turn lamp or right turn lamp is being actively commanded by the trailer brake control module.
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Conditions for Setting the DTC
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B3887 02 or B3888 02
The trailer brake control module detects a short to ground on the appropriate turn signal control circuit.
B3887 04 or B3888 04
The trailer brake control module detects an open/ high resistance in the appropriate turn signal control circuit.
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Action Taken When the DTC Sets
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The appropriate trailer turn signal lamp will be inoperative.
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Conditions for Clearing the DTC
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•
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The DTC will be current for as long as the fault is present.
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•
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When the fault is no longer present, the DTC will be a history DTC.
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A history DTC will clear after 40 ignition cycles.
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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
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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Ignition ON, observe the function of the left trailer turn signal lamp and the right trailer turn signal lamp while commanding the Left Trailer Turn Signal Lamp and the Right Trailer Turn Signal Lamp ON and OFF with a scan tool. The left trailer turn signal lamp and the right trailer turn signal lamp should turn ON and OFF while changing between the commanded states.
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1.
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Ignition OFF, disconnect the X1 harness connector at the K68 trailer lighting control module.
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2.
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Test for infinite resistance between the control circuit terminal listed below and ground:
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Right trailer turn signal lamp control terminal 2
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Left trailer turn signal lamp control terminal 17
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3.
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If less than the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the X88 trailer connector.
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4.
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Test for less than 1 Ω between the control circuit terminals listed below:
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Control terminal 2 at the K68 trailer lighting control module and control terminal 4 at the X88 trailer connector.
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Control terminal 17 at the K68 trailer lighting control module and control terminal 1 at the X88 trailer connector.
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5.
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If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance.
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6.
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If all the circuits test normal, replace the K68 trailer lighting control module.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for trailer brake control module replacement, programming and setup
