B1401: Driver Window One-Touch Relay Short to Ground
The B1401 code indicates that the comfort system control module (GEM/SJB in Ford vehicles) has detected a short to ground in the circuit for the driver's one-touch window relay. This relay controls the automatic up/down function of the driver's window, allowing it to operate without holding the switch. A short to ground prevents the relay from activating correctly, disabling the one-touch feature and potentially causing the system to enter a protection mode.
1. Commonly Affected Makes
2. Most Common Causes
- Internal short circuit in the driver's one-touch control relay coil
- Damaged insulation on the relay control circuit wiring contacting chassis ground
- Corroded or bent pins in the GEM/SJB module or window motor connector causing a short to ground
- Internally damaged relay control transistor in the GEM/SJB module
- Short to ground in the driver's window motor winding (winding shorted to motor housing)
3. Symptoms You Will Notice
- Driver's window one-touch up/down function inoperative
- Window may only operate while holding the switch
- Possible intermittent window operation
- GEM/SJB module may enter protection mode, disabling other comfort features
4. Step-by-Step Diagnosis
Scan for B1401 and related codes; clear and retest to confirm active fault
Visually inspect wiring harness between GEM/SJB and driver window motor for damage or chafing
Check relay control circuit for continuity to ground using a multimeter
Test the one-touch relay by swapping with a known good relay if accessible
Inspect GEM/SJB module connector pins for corrosion or damage
If all else passes, suspect internal GEM/SJB module failure
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive. The main issue is loss of the one-touch window function, and the window can still be operated manually by holding the switch. However, if the short is severe, it may cause a fuse to blow or affect other systems, so it should be diagnosed promptly.
How much does it cost to fix?▼
Repair costs vary widely depending on the root cause. A simple wiring repair may cost $100-$200, while replacing the GEM/SJB module can range from $400-$800 including labor. Diagnosis typically adds $100-$150.