DTC B258A
Diagnostic Instructions
DTC Descriptor
| DTC B258A 01: Low Beam Control Circuit Short
to Battery |
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Low Beam Control
|
1
|
2
|
B258A 01*
|
-
|
* Headlamp low beam always OFF
1. Headlamp low beam always ON
2. Headlamp low beam always OFF
|
|
| |
Circuit/System Description
The body control module (BCM) switches the headlamp low beams ON
as soon it receives a signal from the headlamp switch or ambient
light sensor. When this signal is received by the BCM, it applies a
voltage trough the low beam relay and the low beam supply circuits
which illuminates the low beams.
Conditions for Running the DTC
The headlamp switch in OFF, AUTO or LOW BEAM position.
Conditions for Setting the DTC
The BCM detects a short to battery on the control circuit.
Action Taken When the DTC Sets
Headlamp low beam malfunction.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
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
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, perform the appropriate Headlamp Low Beam Command
test. The appropriate low beam lamp should be ON/OFF.
Circuit/System Testing
| 1. |
Ignition OFF, disconnect the
KR49 Headlamp Low Beam Relay. |
| 2. |
Ignition ON, verify that a
test lamp illuminates between the B+ circuit terminals listed below
and ground: |
| ⇒ |
If the test lamp does not illuminate, test the B+
circuit for a short to ground or open/high resistance. |
| 3. |
Connect a test lamp between
the control circuit of KR49 Headlamp Low Beam Relay terminal 85 and
B+ . |
| 4. |
Command the Headlamp Low Beam
Command ON and OFF with a scan tool. The test lamp should turn ON
and OFF when changing between the commanded states. |
| ⇒ |
If the test lamp is always ON, test the control
circuit for a short to voltage. If the circuit tests normal,
replace the K9 Body Control Module. |
| ⇒ |
If the test lamp is always OFF, test the control
circuit for a short to ground or an open/high resistance. If the
circuit tests normal, replace the K9 Body Control Module. |
| 5. |
Remove the test lamp and
reconnect the KR49 Headlamp Low Beam Relay. |
| 6. |
Disconnect the harness of the
appropriate headlamp and connect a test lamp between the control
circuit terminal 3 and ground. |
| 7. |
Command the Headlamp Low Beam
Command ON and OFF with a scan tool. The test lamp should turn ON
and OFF when changing between the commanded states. |
| ⇒ |
If the test lamp is always ON, test the control
circuit for a short to voltage. If the circuit tests normal,
replace the KR49 Headlamp Low Beam Relay. |
| ⇒ |
If the test lamp is always OFF, test the control
circuit for a short to ground or an open/high resistance. If the
circuit tests normal, replace the KR49 Headlamp Low Beam
Relay. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
