Front Fog Lamp Switch Circuit Malfunction
Table of contents
B2740 CADILLAC Possible Causes
- Faulty Headlamp Switch
- Headlamp Switch harness is open or shorted
- Headlamp Switch circuit poor electrical connection
- Faulty Body Control Module (BCM)
How do I fix code B2740 CADILLAC?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the B2740 CADILLAC code
The cost of diagnosing the B2740 CADILLAC code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B2740 CADILLAC Description
The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The Body Control Module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the fog lamp fuse to the front fog lamp control circuit which illuminates the front fog lamps. With the front fog lamp switch activated the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the front fog indicator. The Diagnostic Trouble Code (DTC) sets when the BCM detects a short to ground in the front fog lamp switch signal circuit.