B257C
DTC B257C or B257D
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B257C 00
-
Left Headlamp Assembly Malfunction
DTC B257D 00
-
Right Headlamp Assembly Malfunction
Diagnostic Fault Information
Circuit/System Description
When the headlight switch is placed in low beam position, the body control module (BCM) energizes the low beam headlamp relay which passes battery voltage to the respective headlamp voltage supply circuits. Each headlamp monitors this voltage and passes this information to the headlamp control module via the local interconnect network (LIN) communication bus.
Conditions for Running the DTC
The headlamps are turned ON.
Conditions for Setting the DTC
The headlamp control module detects a difference between the reported state of the headlamp from the headlamp and the reported state from the headlamp control module.
Action Taken When the DTC Sets
The appropriate headlamp leveling is inoperative.
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists.
Diagnostic Aids
If both DTCs B257C and B257D are set, test the low beam relay for an open condition.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Ignition ON, Low Beams ON, command the Headlamp Leveling Motors test with the scan tool UP and DOWN. Both headlamps should operate to the appropriate position when commanded.
Circuit/System Testing
1. Ignition OFF, disconnect the appropriate harness connector at the inoperative headlamp listed below:
* E13L Headlamp Assembly - Left
* E13R Headlamp Assembly - Right
2. Test for less than 5 ohms between the appropriate headlamp ground circuit harness connector terminal 3 and ground.
• If greater than the specified value, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the appropriate ignition circuit listed below and ground:
* E13L Headlamp Assembly - Left terminal B X107
* E13R Headlamp Assembly - Right terminal B X108
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate inoperative headlamp.
4. If all circuits test normal, replace the K26 Headlamp Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Headlamp Replacement (Left Side) Headlamp Replacement (Left Side)
* Control Module References Control Module References for headlamp control module replacement, setup and programming