B1407

What Does Code B1407 Mean?

DTC B1407 indicates an open circuit condition detected in the electrical path responsible for controlling the upward movement of the driver’s side power window. This diagnostic trouble code is typically set by the Body Control Module (BCM) or a dedicated Door Control Module (DCM), which monitors the operational status and electrical integrity of power window circuits. When the driver’s side window switch is actuated to the “up” position, the module expects to see a specific voltage drop or current flow through the window motor’s “up” winding. If the module detects an abnormally high resistance or a complete interruption (open circuit) in this particular circuit, it interprets this as a fault and logs B1407. This prevents the module from successfully supplying power or completing the ground path required for the window motor to move the glass upward, thereby disabling the function and often illuminating a warning light or storing a diagnostic fault.

Common Symptoms

• The driver’s power window will not move up when the switch is actuated.
• The driver’s power window may move down normally, but not up.
• Intermittent operation of the driver’s power window, failing to move up at times.
• Audible clicking from the window switch or module when attempting to move the window up, but no motor engagement.
• Other power windows (passenger, rear) operate normally.

What Causes the Code B1407?

• Faulty Driver’s Side Power Window Switch: An internal electrical fault, such as a broken contact, corroded terminal, or mechanical wear, specifically affecting the “up” circuit within the switch assembly.
• Open Circuit in Wiring Harness: A break, fray, or severe corrosion in the wiring connecting the driver’s window switch to the window motor, or between the switch/motor and the BCM/DCM. This is frequently observed in the flexible wire loom located in the door jamb due to repeated stress from door opening and closing.
• Faulty Driver’s Side Power Window Motor/Regulator Assembly: An internal electrical open circuit within the motor’s windings specifically responsible for the “up” direction, or a failure of the internal thermal breaker. The mechanical regulator itself could also bind, leading to excessive current draw that trips the motor’s internal protection, but an “open circuit” specifically points to an electrical interruption.
• Corroded or Loose Electrical Connectors: Poor electrical contact at the terminals of the driver’s window switch, the window motor, or the BCM/DCM due to corrosion, improper seating, or pin spreading.
• Faulty Body Control Module (BCM) or Door Control Module (DCM): While less common, an internal failure within the module responsible for controlling the window motor’s “up” circuit can lead to this code. This could involve a failed driver circuit or monitoring component within the module itself.

How to Diagnose and Troubleshoot

Diagnosis of B1407 requires systematic electrical testing using a digital multimeter (DMM) and potentially an OBD-II scan tool with bi-directional control capabilities.

1. Initial Scan and Verification: Connect an OBD-II scan tool to confirm B1407 is present. Check for any related power window or BCM/DCM communication codes that might provide additional context. Note if the code is current or a history code.
2. Visual Inspection:
   • Carefully inspect the wiring harness running from the vehicle body into the driver’s door, specifically in the flexible conduit within the door jamb. Look for signs of chafing, cuts, pinching, or corrosion on the wires.
   • Remove the driver’s door panel and inspect the electrical connectors at the window switch and the window motor. Look for corrosion, bent pins, or signs of overheating.
3. Power and Ground Test at Driver’s Window Switch:
   • With the ignition ON, disconnect the electrical connector from the driver’s window switch.
   • Using a DMM, check for constant 12V power at the appropriate terminal(s) of the harness connector (refer to wiring diagrams).
   • Verify a good chassis ground at the appropriate ground terminal(s) of the harness connector. Lack of either power or ground will need to be traced back to the fuse box, BCM/DCM, or ground point.
4. Driver’s Window Switch Continuity Test:
   • With the switch disconnected from the vehicle harness, use the DMM in continuity or resistance mode.
   • Consult the wiring diagram to identify the input and output terminals for the “up” circuit of the switch.
   • Actuate the switch to the “up” position and test for continuity between the designated input and output terminals. A reading of “OL” (open line) or very high resistance indicates an internal switch fault. A reading close to zero ohms indicates good continuity.
5. Voltage Drop/Continuity Test to Window Motor:
   • If the switch tests good, reconnect it and access the window motor’s electrical connector.
   • With the motor disconnected, use the DMM to back-probe the harness connector while an assistant actuates the driver’s window switch to the “up” position.
   • You should observe a momentary 12V signal on one of the motor control wires and ground on the other (or vice-versa, depending on design). If power and ground are present at the motor connector when the switch is activated “up,” the wiring from the switch/BCM to the motor is likely intact.
   • If no voltage or an incorrect voltage is observed, perform a wire continuity test between the switch connector and the motor connector for the “up” circuit wires. Also check for shorts to power or ground.
6. Window Motor Resistance Test:
   • With the window motor disconnected from the vehicle harness, use the DMM to measure the resistance across the motor’s power and ground terminals. While specific “up” and “down” windings aren’t always externally identifiable, an extremely high resistance or “OL” reading suggests an internal open circuit within the motor assembly. Compare to manufacturer specifications if available.
   • If accessible, visually inspect the motor’s brushes and commutator for wear or damage.
7. Bi-directional Control (if applicable): If your scan tool supports bi-directional control, attempt to command the driver’s window up directly through the BCM/DCM. If the window still does not move up, and power/ground are confirmed at the motor, it further points to a faulty motor or a significant mechanical binding. If it does move up, the fault likely lies with the window switch or its immediate wiring.

Recommended Repairs and Solutions

Once the root cause of B1407 has been accurately identified through thorough diagnostics, the following repairs are typically recommended:

• Replace Driver’s Power Window Switch: If the internal continuity test reveals an open circuit or excessive resistance when the switch is in the “up” position, replacing the entire driver’s master window switch assembly is the most effective solution. Ensure a high-quality OEM or reputable aftermarket replacement part is used.
• Repair Wiring Harness: For damaged wires in the door jamb or within the door panel, perform professional wiring repairs. This involves cutting out the damaged section, soldering in a new section of wire of the correct gauge, and sealing the splice with heat-shrink tubing. Replace any corroded or damaged electrical connectors. Avoid simply taping over damaged insulation, as this is a temporary fix that will likely fail again.
• Replace Driver’s Power Window Motor/Regulator Assembly: If the motor resistance test indicates an internal open circuit, or if the motor does not respond to verified power and ground signals, the entire power window motor and regulator assembly should be replaced. It’s often recommended to replace both the motor and regulator as a single unit, as they are typically sold together and a binding regulator can lead to premature motor failure.
• Clean and Secure Connectors: If diagnosis points to corroded or loose connections, clean the affected terminals using an electrical contact cleaner and a small brush. Apply a small amount of dielectric grease to prevent future corrosion, and ensure the connectors are securely seated and latched. Repair any spread or bent pins within the connector.
• BCM/DCM Replacement (Last Resort): Only consider replacing the BCM or DCM after all other components (switch, motor, wiring, connectors) have been thoroughly tested and verified to be in good working order. Module replacement often requires specialized programming and calibration with a factory-level scan tool.

After any repair, clear the DTC B1407 from the system memory and operate the driver’s power window through its full range of motion multiple times to confirm the repair. Re-scan the system to ensure the code does not return.