B1399 — Driver Power Window One Touch Window Relay Circuit Open

What is the most common cause of B1399?

The most common causes are: body control module (BCM) fault, corroded or loose connectors, faulty switch, motor or actuator of the affected system.

What are the symptoms of B1399?

Drivers most often notice: the affected function (locks, windows, lighting, wipers) works intermittently or not at all, no impact on engine operation in most cases, warning light on the dashboard.

Will B1399 clear itself?

Sometimes B1399 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

How much does it cost to fix B1399?

Repair wiring or connectors — $80–$250; BCM repair or replacement — $300–$900; Replace the switch or actuator — $120–$450. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

How do I diagnose B1399 myself?

Start with a scan: confirm B1399, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the driver power window one touch window relay, and verify the suspect component against live data before buying parts.

When your scan tool displays trouble code B1399, it tells you the body control module has detected an interruption in the electrical circuit responsible for the driver's power window one-touch relay. The full diagnostic description reads "Driver Power Window One Touch Window Relay Circuit Open," and it falls within the B-series codes that cover body electronics rather than engine management systems.

This code triggers because the circuit feeding the driver's window one-touch relay no longer forms a complete path for electrical current. Think of it as a broken garden hose — the module sends voltage down the line expecting it to return, but the stream never makes it back. Typical culprits include cut or corroded wires, connectors that have worked loose or filled with moisture, a fuse that has opened, or a relay that has failed internally. The body control module monitors this circuit continuously, and once it spots the voltage reading outside acceptable parameters — usually across multiple ignition cycles — it logs B1399 and captures a freeze frame snapshot.

That freeze frame data is genuinely useful. It records engine speed, load percentage, coolant temperature, and vehicle speed the instant the fault occurred. Checking those conditions helps you recreate the exact scenario during testing, which dramatically narrows down whether the problem is environmental — moisture, temperature — or structural. B1399 will not clear on its own; the underlying fault must be repaired and the module retested across a complete drive cycle before the light goes out.

Symptoms

• The driver's power window one-touch up or down function stops responding or operates only intermittently
• Other comfort features on the same circuit — possibly related locks or interior lighting — behave erratically or fail entirely
• The check engine or body warning light illuminates on the instrument cluster
• Engine performance and drivability remain completely unaffected in most cases
• Window movement is sluggish or the motor strains when attempting operation
• The relay clicks are absent when commanding the window to operate

Causes

The most frequent trigger for B1399 is a blown fuse protecting the window relay circuit. Fuse panels in the cabin or underhood can suffer from thermal fatigue, corrosion at the blade terminals, or simply age — a single overcurrent event opens the circuit completely.

Loose, backed-out, or heavily corroded electrical connectors at the driver's door harness rank second. Door connectors experience constant flexing every time the door opens and closes, and the pins can spread, develop corrosion deposits, or push back from their housings.

A broken wire inside the driver's door wiring harness — especially near the door jamb pass-through — exposes the copper conductors to repeated bending and abrasion until one or more strands snap.

An internally failed driver's window one-touch relay cannot complete the circuit even though everything upstream reads normal. Relays wear out from normal use and contacts pit or fuse together.

Faulty window switches or worn window motors draw excessive current, which either blows the fuse repeatedly or creates a voltage drop the module interprets as an open circuit.

Moisture intrusion in door cavities or hatch areas corrodes connector pins and wiring insulation, introducing resistance or outright opens.

A failing body control module can misread valid signals from the circuit or fail to supply power to the relay altogether, though this ranks lower on the probability scale.

How to Diagnose

Start by connecting an OBD2 scanner, record all stored codes, and capture the freeze frame data for B1399 before clearing anything. Note engine conditions at the moment of failure — temperature, load, road speed — and replicate them during your road test.

Scan for any related trouble codes in the B0xxx range. Body control modules often log companion codes when a single wiring problem affects multiple functions, and addressing the root cause clears everything together. Cross-reference factory TSBs for your specific make and model year; manufacturers have published software updates and harness modifications that eliminate repeat failures on certain platforms.

Perform a thorough visual inspection of the driver's door wiring harness. Pull the door panel if necessary and examine the full length of wire for cracked insulation, green corrosion growth, and any signs of heat discoloration near the relay or motor connections. Check connector housings for moisture tracks, bent pins, and missing seals.

Measure circuit continuity end-to-end with a digital multimeter from the relay output back to the body control module input. Wiggle the harness gently during testing — especially through the door jamb — and watch for readings that jump between open and normal resistance, which pinpoints intermittent opens.

Use your scan tool's live data to monitor window switch and motor parameters while operating the controls. Compare voltage and current draw against known-good specifications for your vehicle.

After repairs, clear B1399, complete a full drive cycle matching the freeze frame conditions, and verify the code does not return before considering the diagnosis closed.

Repair Options

B1399 repair costs vary widely depending on which component failed:

• Wiring repair or connector replacement: $80–$250
• Body control module diagnosis, repair, or replacement: $300–$900
• Driver window switch or window motor replacement: $120–$450

Parts pricing depends on your vehicle make and whether you source OEM or aftermarket components. Labor rates at independent shops typically fall between $75 and $125 per hour, while dealership labor often runs higher.

Total out-of-pocket for a typical B1399 repair ranges from $80 on the low end — cleaning a corroded connector and replacing a fuse — up to $900 if the body control module requires replacement and reprogramming. The majority of cases land in the $150–$400 range. Always verify the root cause with electrical testing before committing to expensive component replacement; a blown fuse might be masking a shorted motor that will blow the new fuse repeatedly if left undiagnosed.

Driving Safety Verdict

B1399 carries a short severity rating. The fault resides entirely within the body's comfort and convenience systems, so engine operation, transmission function, and braking remain unaffected. You can drive the vehicle normally while the light is active.

That said, if the driver's window fails completely, you lose the ability to communicate with other drivers through the window or exit quickly in an emergency. Exterior lighting and wiper failures linked to the same circuit create safety hazards in low visibility. Central locking faults associated with body module issues could leave the vehicle unsecured. Address B1399 promptly, but it does not require roadside breakdown service or immediate towing.

Related OBD2 codes

• B1300: Power Door Lock Circuit Failure
• B1301: Power Door Lock Circuit Open
• B1302: Accessory Delay Relay Coil Circuit Failure
• B1303: Accessory Delay Relay Coil Circuit Open
• B1304: Accessory Delay Relay Coil Circuit Short To Battery
• B1305: Accessory Delay Relay Coil Circuit Short To Ground