Friday, October 8, 2021

2010 Cadillac Truck SRX FWD V6-3.0L Page 297

2010 Cadillac Truck SRX FWD V6-3.0L Page 297



Component Testing



Relay Test



1. Ignition OFF, disconnect the KR49 headlamp low beam relay.



2. Test for 60-180 ohm between terminals 85 and 86.



瀚慖f not within the specified range, replace the KR49 headlamp low beam relay.



3. Test for infinite resistance between the following terminals:



* 30 and 86



* 30 and 87



* 30 and 85



* 85 and 87



瀚慖f not the specified value, replace the KR49 headlamp low beam relay.



4. 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 ohm between terminals 30 and 87.



瀚慖f greater than the specified range, replace the KR49 headlamp low beam relay.



Repair Instructions



Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.



* Headlamp Replacement (See: Lighting and Horns/Headlamp/Service and Repair/Removal and Replacement/Headlamp Replacement)



* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay



Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power



Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))



* Control Module References (See: Testing and Inspection/Programming and Relearning) for headlamp control module replacement, setup



and programming



B257D



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.



DTC Descriptors



DTC B257C 00



- Left Headlamp Assembly Malfunction



DTC B257D 00



- Right Headlamp Assembly Malfunction



Diagnostic Fault Information



Circuit/System Description



The headlamp control module calculates the headlamp angle and sends commands to the left and right adaptive forward lighting system headlamp



actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module



monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected,



a DTC will be stored in memory and the driver will be notified with a message displayed over the driver information center located on the

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