B1399 — Driver Power Window One Touch Window Relay Circuit Open #

Note: The code description may vary depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) documentation for precise terminology.

• Ford: Driver Power Window One Touch Window Relay Circuit Open
• Jaguar/Land Rover: Driver Side Window One Touch Relay Circuit Open
• Toyota: Driver’s Power Window One-Touch Up/Down Relay Circuit Open
• Chrysler: Power Window Relay Circuit Open – Driver Side

Summary of Code B1399 #

The B1399 code signals a detected issue in the electrical circuit that controls the one-touch relay functionality for the driver’s power window. This system allows the window to move fully up or down with a single press of the switch, relying on a specific relay to operate correctly. When the vehicle’s body control module (BCM) senses an open circuit—meaning there is a break or significant resistance in the relay’s wiring or connections—it triggers the B1399 code. This fault could be due to wiring, relay, switch, or even the BCM itself. Depending on the OEM’s design, this code may disable the one-touch feature or the entire window operation for safety.

Frequent Symptoms for Code B1399 #

A vehicle registering B1399 often exhibits clear, frustrating signs related to the driver’s power window. While some symptoms are subtle, others can impact daily convenience and safety. If your vehicle is showing this code, you might notice:

• Driver’s window one-touch up/down function not working
• Window only responds to manual (continuous) switch input
• No response from the driver’s window switch at all
• Intermittent or jerky window movement
• Unusual clicking or relay noises from the door or dash area
• In some vehicles, a warning on the dashboard or DTC stored with no obvious symptoms

Probable Causes for Code B1399 (Most to Least Common) #

The B1399 code is most frequently triggered by electrical issues, but the root cause can vary. Start with the most common culprits and proceed methodically:

1. Faulty one-touch power window relay (relay contacts burned, stuck, or corroded)
2. Open in the wiring harness (broken wire, poor connection, corroded terminal between relay and BCM or switch)
3. Defective driver’s power window switch (internal circuit failure or worn contacts)
4. Issues in the driver’s side window motor (rare, but possible if equipped with integrated relay feedback)
5. Body Control Module (BCM) malfunction (internal relay driver or logic fault)
6. Blown fuse or circuit protector for the window circuit

Step-by-Step Diagnosis for Code B1399 #

Diagnosing B1399 requires patience and a logical sequence. It’s like tracing a river upstream to find where the flow is blocked—each step rules out a possible obstruction. Here’s a professional approach:

• 1. Confirm the code: Use a scan tool to verify B1399 and clear it. Operate the window and see if the code returns.
• 2. Visual inspection: Check the driver’s window switch, relay, and wiring for obvious damage, corrosion, or loose connections.
• 3. Test the relay: Remove and bench-test the one-touch relay according to OEM specs. Swap with a known-good relay if possible.
• 4. Check fuse(s): Inspect the related fuse for continuity and correct amperage.
• 5. Circuit testing: With the relay removed, use a multimeter to check for continuity and voltage at the relay socket and switch wiring.
• 6. Switch test: Test the driver’s window switch for correct operation and continuity in all positions.
• 7. BCM evaluation: If all wiring and hardware check out, consider a software reset or update for the BCM, or consult OEM diagnostics for module fault tracing.

Possible Repairs for Code B1399 #

Once you’ve pinpointed the fault, the repair should address the specific root cause. Here are the most effective fixes linked to the issues above:

• Replace the faulty one-touch relay
• Repair or replace damaged wiring/connectors in the driver’s door or under the dash
• Replace the driver’s power window switch
• Repair or replace the window motor (if feedback circuit failure is confirmed)
• Replace or reprogram the BCM (if internal faults are proven and all else fails)
• Replace blown fuse; investigate for short circuits if fuse blows again

Can You Drive With Code B1399? #

Yes, but with limitations. Code B1399 will not affect your core driving safety systems, engine, or brakes. However, the inability to open or close the driver’s window with the one-touch feature—or at all—can be a significant inconvenience. In some situations (toll booths, drive-thrus, emergency exits), a non-functioning window can create safety challenges. If the window won’t close, your vehicle is exposed to weather, theft, or vandalism. For these reasons, it’s wise to address the problem promptly, but short-term driving is generally safe.

Vehicles Most Commonly Affected by Code B1399 #

While B1399 is a generic body code, it’s most frequently reported on vehicles where the driver’s one-touch window system relies on a dedicated relay and BCM control. Some of the most commonly affected models include:

• Ford Focus, Fusion, F-150 (2005–2017)
• Jaguar XF, XJ, XE (2010–2018)
• Land Rover Discovery, Range Rover Evoque (2011–2019)
• Chrysler 300, Dodge Charger (2008–2015)
• Toyota Camry, Corolla (2012–2019)

Common Mistakes & Best Practices for Code B1399 #

Even seasoned technicians can fall into traps when diagnosing B1399. Keep these lessons in mind to avoid wasted time and money:

• Replacing the window motor without verifying relay or switch function
• Overlooking simple wiring issues in the door harness (especially at flex points)
• Ignoring corroded connectors or water intrusion in the door module
• Skipping fuse checks—sometimes a blown fuse is both symptom and cause
• Not consulting OEM wiring diagrams and relay locations (they can differ by trim or year)
• Always reset and recheck after repair to confirm the fix

Express FAQ for Code B1399 #

You’ve got questions; here are straight answers from the service bay:

• Q: Can I still manually operate the driver’s window with B1399?
  A: In many cases, yes—the manual up/down function works, but one-touch is disabled. However, if the relay or main switch circuit is fully open, the window may not move at all.
• Q: Is B1399 likely to recur after repair?
  A: If repaired correctly (wiring, relay, or switch replaced as needed), recurrence is rare. Persistent codes typically indicate a deeper electrical issue or BCM fault.