PRE-RELEASE
DTC B258A
| DTC B258A |
| 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
provides an overview of each diagnostic category.
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| DTC Descriptor |
DTC B258A 01
Low Beam Control Circuit Short to Battery
DTC B258A 02
Low Beam Control Circuit Short to Ground
DTC B258A 04
Low Beam Control Circuit Open
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
| Headlamp Low Beam Relay Control | B258A 02 | B258A 04 | B258A 01 | - |
| 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 supplies battery voltage to the respective headlamp control circuits.
| Conditions for Running the DTC |
The headlamp switch is in the low beam position.
| Conditions for Setting the DTC |
B258A 01
The BCM detects a short to voltage in the headlamp low beam relay control circuit.B258A 02
The BCM detects a short to ground in the headlamp low beam relay control circuit.B258A 04
The BCM detects an open/high resistance in the headlamp low beam relay control circuit.| Action Taken When the DTC Sets |
B258A 01 or B258A 04
The low beam headlamps will be inoperative.B258A 02
The low beam headlamps will be continuously illuminated.| Conditions for Clearing the DTC |
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The DTC will be current for as long as the fault is present.
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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 50 ignition cycles.
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| Reference Information |
Schematic Reference
Headlights/Daytime Running Lights (DRL) 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 scan tool information
| Circuit/System Verification |
Ignition ON, command the Headlamp Low Beam ON and OFF with a scan tool. The low beam lamp should turn ON and OFF when changing between the commanded states.
| Circuit/System Testing |
| 1. |
Ignition OFF, disconnect the KR49 headlamp low beam relay.
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| 2. |
Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.
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| 3. |
If the test lamp illuminates, test the control circuit for a short to voltage
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| 4. |
Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.
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| 5. |
If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
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| 6. |
Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground.
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If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
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| 8. |
Connect a 15A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the E4G headlamp-left low beam and the E4H headlamp-right low beam are activated.
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| 9. |
If the E4G headlamp-left low beam and the E4H headlamp-right low beam do not activate, test the control circuit for a short to ground or an open/high resistance.
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| 10. |
Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
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| 11. |
Ignition ON, command the low beam lamps 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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| 12. |
If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.
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| 13. |
If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
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| 14. |
If all circuits test normal, test or replace the KR49 headlamp low beam relay.
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| Component Testing |
Relay Test
| 1. |
Ignition OFF, disconnect the KR49 headlamp low beam relay.
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| 2. |
Test for 60-180 Ω between terminals 85 and 86.
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| 3. |
If not within the specified range, replace the KR49 headlamp low beam relay.
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| 4. |
Test for infinite resistance between the following terminals:
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30 and 86
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30 and 87
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30 and 85
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85 and 87
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| 5. |
If not the specified value, replace the KR49 headlamp low beam relay.
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| 6. |
Install a 15A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.
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| 7. |
If greater than the specified range, replace the KR49 headlamp low beam relay.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Relay Replacement (Attached to Wire Harness)
Relay Replacement (Within an Electrical Center)
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Control Module References
for BCM replacement, setup, and programming
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