B1402: Driver Window Down Switch Circuit
The B1402 code indicates a fault in the driver's window down switch circuit. This manufacturer-specific code is triggered when the Body Control Module (GEM in Ford) detects an anomaly in the signal circuit of the driver's side window down switch, typically due to a voltage signal out of range, an open circuit, or a short to ground or battery. The system monitors the resistance or voltage in the switch circuit to determine the switch position and status.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or worn driver window switch
- Damaged, corroded, or loose wiring in the switch circuit
- Short to ground or battery in the switch harness
- Open circuit in the wiring between the switch and the GEM/SJB module
- Bent, corroded, or moisture-damaged pins in the switch connector
3. Symptoms You Will Notice
- Driver window does not roll down using the switch
- Intermittent window operation
- Window may only work from the master switch on another door
4. Step-by-Step Diagnosis
Check for technical service bulletins (TSBs) related to B1402 for your vehicle
Inspect the driver window switch and connector for damage, corrosion, or loose pins
Test the switch circuit for voltage, ground, and continuity using a multimeter
Check for shorts to ground or battery in the wiring harness
If wiring and switch are good, test the GEM/SJB module for proper operation
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the driver window may not operate correctly. The issue does not affect critical safety systems.
How much does it cost to fix?▼
Repair costs typically range from $100 to $300, depending on whether the switch, wiring, or module needs replacement.