PRE-RELEASE
DTC B3948 or B3949
| DTC B3948 or B3949 |
| 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 B3948 02
Left Front Turn Signal Circuit Short to Ground
DTC B3948 04
Left Front Turn Signal Circuit Open
DTC B3949 02
Right Front Turn Signal Circuit Short to Ground
DTC B3949 04
Right Front Turn Signal Circuit Open
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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Left Front Turn Signal
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B3948 02
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B3948 04
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1
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-
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Right Front Turn Signal
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B3949 02
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B3949 04
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1
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-
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1. Turn signal lamp inoperative
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| Circuit/System Description |
Ground is applied at all times to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in either the turn right or turn left position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a voltage to the front/side and rear turn signal lamps through their respective voltage supply circuits.
| Conditions for Running the DTC |
B3948 02, B3948 04, B3949 02 and B3949 04
The appropriate turn signal is active.| Conditions for Setting the DTC |
B3948 02 and B3949 02
The BCM detects a short to ground on the control circuit.B3948 04 and B3949 04
The BCM detects an open control circuit.| Action Taken When the DTC Sets |
The appropriate turn signal lamp is inoperative.
| Conditions for Clearing the DTC |
The condition for setting the DTC is no longer present.
| Reference Information |
Schematic Reference
Exterior Lights 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 |
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Ignition ON, perform the Left Front Turn Signal Lamp test. The left front turn signal lamp and turn signal repeater light should be ON/OFF.
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Ignition ON, perform the Right Front Turn Signal Lamp test. The right front turn signal lamp and turn signal repeater light should be ON/OFF.
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| Circuit/System Testing |
| 1. |
Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp.
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| 2. |
Test for less than 5 Ω between the appropriate turn signal lamp ground circuit harness connector listed below and ground.
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E4RF Turn Signal Lamp - Right Front ground circuit harness connector terminal 1
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A9A Outside Rearview Mirror - Driver ground circuit harness connector terminal 4
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E4LF Turn Signal Lamp - Left Front ground circuit harness connector terminal 1
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A9B Outside Rearview Mirror - Passenger ground circuit harness connector terminal 4
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| 3. |
If greater than the specified range, test the ground circuit for an open/high resistance.
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| 4. |
Connect a test lamp between the appropriate turn signal lamp control circuit harness connector listed below and ground.
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E4RF Turn Signal Lamp - Right Front circuit harness connector terminal 2
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A9A Outside Rearview Mirror - Driver circuit harness connector terminal 16
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E4LF Turn Signal Lamp - Left Front circuit harness connector terminal 2
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A9B Outside Rearview Mirror - Passenger circuit harness connector terminal 16
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| 5. |
Command the appropriate Turn Signal Lamp test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
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| 6. |
If the test lamp is always ON, test the Signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.
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| 7. |
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 K9 Body Control Module.
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| 8. |
If all the circuits test normal, replace the appropriate turn signal lamp.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Outside Rearview Mirror Glass Replacement
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Tail Lamp Replacement
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Front Turn Signal Lamp Bulb Replacement
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Control Module References
for information on BCM replacement, setup, and programming
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