2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 294
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Headlamps On Switch, Park Lamps Switch and Automatic Headlamps Disable Switch parameters while
selecting the headlamp control switch between the Off, park lamps and headlamps settings. Each parameter should be Inactive and change to Active
as each setting is selected.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
2. Ignition OFF, test for less than 30 ohm between the ground circuit terminal 6 and ground.
瀚慖f greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Park Lamps Switch parameter is Inactive.
瀚慖f not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K9 BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 6. Verify the scan tool Park Lamps
Switch parameter is Active.
瀚慖f not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9
BCM.
5. Verify the scan tool Headlamps On Switch parameter is Inactive.
瀚慖f not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K9 BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 6. Verify the scan tool Headlamps On
Switch parameter is Active.
瀚慖f not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9
BCM.
7. Verify the scan tool Automatic Headlamps Disable Switch parameter is Inactive.
瀚慖f not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the K9 BCM.
8. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the ground circuit terminal 6. Verify the scan tool Automatic
Headlamps Disable Switch parameter is Active.
瀚慖f not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9
BCM.
9. 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
B257C
DTC B257C or B257D
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.
