2010 Cadillac Truck SRX FWD V6-3.0L Page 458

2010 Cadillac Truck SRX FWD V6-3.0L Page 458

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 B1405 02

- Control Module Voltage Reference Output 2 Circuit Short to Ground

DTC B1405 03

- Control Module Voltage Reference Output 2 Circuit Low Voltage

DTC B1405 07

- Control Module Voltage Reference Output 2 Circuit High Voltage

DTC B1529 03

- Control Module Voltage Reference Output 5 Circuit Low Voltage

DTC B1529 07

- Control Module Voltage Reference Output 5 Circuit High Voltage

DTC B257B 03

- Lighting Control Switch Signal Low Voltage

DTC B257B 07

- Lighting Control Switch Signal High Voltage

Diagnostic Fault Information

Circuit/System Description

The body control module (BCM) supplies battery positive voltage to the backlight dimmer switch, which is part of the headlamp switch. When the

backlight dimmer switch is placed in a desired brightness position, reference voltage is applied to the BCM. The BCM interprets this voltage signal,

then applies a pulse width modulated (PWM) voltage to the LED dimming supply circuit to all related interior lamps, illuminating them to the

desired level of brightness.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B1405 03, B1529 03, or B257B 03

The BCM detects less than 0.3 V on the dimmer switch signal circuit.