B1408 — Driver Power Window Up Circuit Short To Battery #

Please note: The code description may vary depending on the vehicle manufacturer. Below are some known variations of this code label:

• Driver Power Window “UP” Circuit High (Ford, Lincoln, Mercury)
• Driver Side Power Window Switch Short to Battery (Toyota, Lexus)
• Front Left Window Lifter Up Command Shorted to Power (Renault, Nissan)
• Driver Window Up Circuit Short to B+ (Chrysler, Dodge, Jeep)

Summary of the B1408 Code #

The B1408 diagnostic trouble code (DTC) indicates that the vehicle’s onboard diagnostics system has detected a short circuit to battery voltage in the driver’s power window “up” circuit. This circuit is responsible for transmitting the signal from the driver’s window switch to the power window motor, commanding the window to move upward. A “short to battery” means that the circuit is unexpectedly receiving full battery voltage, even when it shouldn’t, which can interfere with normal window operation. In many cases, this issue can cause the window to move erratically, become stuck, or even make the switch or wiring feel warm to the touch. Prompt diagnosis is crucial to prevent further electrical problems or inconvenience.

Common Symptoms for Code B1408 #

When a B1408 code is present, you might notice changes in the way your driver’s power window behaves. Depending on the severity of the short circuit, some symptoms may be subtle, while others can be quite obvious. Here’s what you might encounter:

• Driver’s window won’t move up or only works intermittently
• Window moves up on its own without pressing the switch
• Unusual clicking or buzzing sounds from inside the door
• Blown fuse related to the power windows
• Driver window switch feels warm or hot to the touch
• Other electrical issues in the driver’s door (mirrors, locks)
• Illuminated check engine light or other dash warning

Likely Causes for Code B1408 (Ranked by Frequency) #

The B1408 code is most often triggered by issues affecting the wiring or components in the driver’s power window system. Some causes are more common than others, depending on vehicle age and usage. Here’s a ranked list, most to least likely:

1. Damaged wiring harness in the driver’s door hinge area (wires pinched, cut, or frayed)
2. Faulty driver’s window switch (internal short or corrosion)
3. Shorted window motor or regulator assembly (internal electrical fault)
4. Poor ground connection or loose connector at the window motor or switch
5. Water intrusion causing corrosion in connectors or the switch
6. Incorrect installation of aftermarket electronics (alarm, remote start, etc.)

Step-by-Step Diagnosis for Code B1408 #

Diagnosing B1408 requires a methodical approach, as electrical faults can be tricky to spot. Here’s a proven step-by-step process to help you pinpoint the root cause:

1. Verify the code using a compatible OBD-II or EOBD scanner—clear the code and see if it returns after a window operation.
2. Check for related codes (such as B1407, B1410) that may provide additional clues.
3. Inspect all fuses related to the power window circuit and replace any that are blown.
4. Remove the driver’s door panel and visually inspect the wiring harness—pay special attention to the area where wires pass from the body into the door (look for pinched, cut, or frayed wires).
5. Test the driver’s window switch with a multimeter for shorts between the “up” circuit and battery voltage when the switch is at rest.
6. Unplug the window motor and check for continuity to battery voltage in the harness side connector—there should be none when the switch is not pressed.
7. Check for corrosion or moisture in all connectors, especially after heavy rain or washing.
8. If no faults are found, test the window motor for internal shorts using a multimeter or by substitution with a known good unit.

Possible Repairs for Code B1408 #

Once you’ve pinpointed the fault causing B1408, repairs will focus on restoring proper electrical integrity in the “up” circuit. Depending on your findings, here’s what may need to be done:

• Repair or replace damaged wiring in the driver’s door harness
• Replace the faulty driver’s window switch if it’s internally shorted
• Replace the window motor/regulator assembly if it’s found to be shorted
• Clean or replace corroded connectors and apply dielectric grease to prevent future issues
• Reseat or secure loose connectors at the switch or motor
• Correct any incorrect aftermarket wiring that’s tapping into the window circuit
• Replace blown fuses after repairs are confirmed

Is It Safe to Drive with Code B1408? #

Limited — While the B1408 code does not directly affect engine or brake performance, it can compromise driver comfort and convenience by disabling or causing erratic behavior in the driver’s window. In rare cases, persistent electrical shorts could lead to further electrical failures or even a risk of fire if left unaddressed. It’s best to avoid using the driver’s window switch until repairs are made, and have the issue resolved as soon as possible.

Vehicles Most Commonly Affected by B1408 #

This code is most frequently reported on vehicles with power windows and multiplexed door modules, especially those with high usage or in climates prone to moisture. Brands with higher incidence include:

• Ford/Lincoln/Mercury (especially F-series, Fusion, and Explorer)
• Toyota/Lexus (Camry, Corolla, RAV4, ES-series)
• Chrysler/Dodge/Jeep (Ram, Grand Cherokee, Charger)
• Renault/Nissan (Megane, Altima, Qashqai)

Common Mistakes & Best Practices for B1408 #

Diagnosing electrical codes like B1408 can be challenging, and mistakes are common. Here are some pitfalls to avoid, along with best practice recommendations:

• Replacing the window motor or switch without checking the wiring harness — always inspect for damaged wires first.
• Overlooking connector corrosion or moisture intrusion — even small amounts can cause shorts.
• Not using a wiring diagram — always reference OEM wiring diagrams to understand circuit paths.
• Neglecting to clear the code after repairs — the code may remain stored even if the fault is gone.
• Forgetting to check for related codes — multiple codes can help pinpoint a fault’s location.

Quick FAQ for Code B1408 #

Q: Can I fix B1408 myself without special tools?
A: Basic troubleshooting (checking fuses, visual inspection) can be done with minimal tools, but a multimeter and access to wiring diagrams are highly recommended for accurate diagnosis.

Q: Will disconnecting the battery clear this code?
A: Disconnecting the battery may temporarily erase the code from memory, but it will return if the underlying fault isn’t repaired. Always fix the root cause for a lasting solution.

Q: Could aftermarket alarm or remote start systems cause this code?
A: Yes, if they’re incorrectly wired into the power window circuit, they can cause shorts or unwanted voltage in the “up” circuit, triggering B1408.