B1421

Code

Other B — Body

Passenger Power Window Motor Circuit Short To Ground

Brand: Other

Type: B — Body

Views: UK: 37 EN: 44 RU: 32

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged wiring insulation contacting chassis ground
Corroded or damaged connector pins/terminals
Internal short in the window motor (armature or brushes)
Faulty window switch shorting to ground
Faulty body/control module output transistor or driver
Aftermarket components or repairs with incorrect wiring

Symptoms

Passenger window will not move or moves intermittently
Blown fuse or repeatedly tripping circuit protection when operating that window
Unusual noise when operating the switch (clicking relays, rapid fuse trips)
Burnt smell near door or switch area
Other door/window functions may be affected if sharing common ground or module

What to check

Use a scan tool to confirm B1421 and view freeze frame or related data
Visually inspect wiring harness through door hinge/boot for abrasion, pinching, or damage
Inspect door and chassis connectors for corrosion, bent pins, or water ingress
Check fuses and circuit breakers for the power window circuit
Operate switch while observing fuse status and module response (use fused test lead when probing)
With ignition off, disconnect the passenger window motor connector and check circuit resistance to ground and to battery

Signal parameters

Vehicle battery voltage: 11–14 V (normal range)
When switch is actuated expect ~9–14 V at the motor power lead (depends on whether module switches ground or +12 V)
Control/return motor lead should not be a direct short to chassis ground (measured low ohms to ground) when connector disconnected — short to ground indicates fault
Typical window motor DC resistance: roughly 0.5–5 ohms (varies by motor); very low resistance may indicate shorted windings
Stalled motor current may be several amps; an abnormally high current or immediate blowing of protection suggests a short to ground

Diagnostic algorithm

Read and record DTCs and freeze-frame data with a scan tool; verify B1421 is current or stored.
Visually inspect the passenger door wiring harness, especially at the door hinge/boot and connector areas; repair any obvious chafing or damage.
Check related fuses/circuit breakers; replace if blown but do not operate the window repeatedly until cause is found.
With ignition OFF, disconnect the passenger window motor connector. Using a digital multimeter, measure resistance/continuity from the motor power lead(s) to chassis ground. A near-zero reading indicates a short to ground in the harness or motor.
With connector disconnected, check harness side: measure resistance from motor power lead to chassis ground. If low, isolate by unplugging intermediate connectors (door jamb, module) until the short clears to locate damage.
If harness side is open/no short, test the motor itself: bench-test motor with a fused 12 V jumper to confirm motor operation and current draw. If the motor draws excessive current or trips protection, replace the motor.
Test the window switch: disconnect switch harness and check for shorts to ground on switch outputs with switch in neutral and operated positions. Replace switch if it shows low-resistance paths to ground when it should not.
If wiring, motor, and switch check good, test the window control module/BCM output transistor. Check for proper output behavior with an oscilloscope or by comparing to known-good channel. Replace module if output driver is shorted to ground.
Repair or replace damaged wiring, connectors, motor, switch, or module as required. After repairs, clear DTCs and perform operational test cycles to confirm repair and that no new codes return.

Likely causes

Chafed harness where it passes through door hinge or body panel contacting ground
Corroded moisture-intruded door connector causing low-resistance path to ground
Failed window motor with internal short between windings and housing
Switch or switch module internal short to ground
Shorted output in the window control module/BCM

Fault status

⚠️ Status

Controller detected a low-resistance short to chassis ground on the passenger power window motor circuit. Circuit protection may have been activated; fault stored when abnormal current/voltage conditions were observed.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3 hours