2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 302
the K9 BCM.
4. Ignition ON, test for less than 0.3 V between signal circuit terminal 12 and ground.
瀚慖f greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the B+ circuit terminal 1. The interior backlighting should be
dimmed.
瀚慖f the interior backlighting is not dimmed, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests
normal, replace the K9 BCM.
6. If all circuits test normal, test or replace the S30 headlamp switch.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Headlamp Switch Replacement (See: Lighting and Horns/Headlamp/Headlamp Switch/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, programming and setup
B258A
DTC B258A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
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/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.
