What Does B1399 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the relay that controls the one-touch automatic up/down feature of the driver's power window. The BCM continuously monitors the relay circuit for proper voltage and continuity, and this fault means it has detected a break in the electrical path, preventing the relay from being energized. This affects only the one-touch convenience feature while basic window operation may still function normally.
Common Causes
40%
Failed or internally open one-touch window relay in the power distribution center or door module
30%
Broken or corroded wiring between BCM and one-touch window relay, often at door hinge flex point
20%
Corroded or loose relay socket terminals causing poor electrical contact
10%
Failed BCM relay driver circuit or internal fault within body control module
Diagnostic Steps
1
Step 1: Locate the driver window one-touch relay (typically in underhood fuse/relay box or driver door module) and perform visual inspection for corrosion, damage, or loose connections at relay socket
2
Step 2: Remove relay and inspect socket terminals for corrosion or burning. Test relay resistance across coil terminals with multimeter (should read 70-120 ohms typically). Swap with known-good relay if available to verify
3
Step 3: With relay removed and ignition on, use multimeter to verify BCM is providing switched ground or power signal to relay socket when window switch is activated in one-touch position (consult wiring diagram for specific pin)
4
Step 4: Check continuity of all wiring between BCM connector and relay socket, paying special attention to door harness flex area. Wiggle wires while testing to identify intermittent opens
5
Step 5: If all wiring and relay test good, verify BCM ground circuits are intact and BCM connector pins are not corroded or backed-out. Clear codes, reinstall components, and perform functional test of one-touch window operation to confirm repair
Estimated Repair Cost
$75 - $400
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the relay that controls the one-touch automatic up/down feature of the driver's power window. The BCM continuously monitors the relay circuit for proper voltage and continuity, and this fault means it has detected a br...
The most common cause of B1399 (Driver Power Window One Touch Window Relay Circuit Open) is: Failed or internally open one-touch window relay in the power distribution center or door module
Typical repair costs for B1399 range from $75 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This fault does not affect vehicle safety or basic window operation. The vehicle is safe to drive, though the one-touch automatic window feature may be inoperative. Repair can be scheduled at convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1399 to identify the root cause.
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Quick Info
Category
Body
System
Body/Convenience Systems
Difficulty
Type
Manufacturer
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