Code
B1402
FIAT
B — Body
Driver window opening circuit
Views:
UK: 3
EN: 6
RU: 15
AI status
Completed
Completed
100%
Causes
- Blown fuse or defective relay in window circuit
- Faulty driver-side window switch
- Broken, pinched or corroded wiring/connectors in the door hinge harness
- Faulty window motor (stator/brush failure)
- Poor or missing ground at motor or module
- Faulty Body Control Module (BCM) or window driver output
Symptoms
- Driver window will not open (stuck closed)
- No motor noise when attempting to open, or only a relay click
- Window works intermittently or only from passenger switches
- Other windows operate normally (isolates problem to driver side)
- DTC stored and may reappear after clearing
- Possible erratic window movement or partial travel
What to check
- Read and record DTC(s) and freeze frame data with a scan tool
- Verify ignition/key position and retest window operation
- Inspect fuses and relays related to power windows
- Visually inspect door jamb harness and connectors for damage, chafing or corrosion
- Operate driver switch and listen for motor/relay noise
- Back-probe motor and switch connectors while commanding the 'open' function to observe voltages
Signal parameters
- Expected supply: battery voltage (~11–14.5 V) present at the motor/switch when commanded
- Polarity: motor circuit is typically polarity-reversed for open vs close (one side positive, other grounded)
- Idle/standby: near 0 V at motor terminals with switch inactive
- Motor current: can draw high current under load (tens of amps); use proper fused test methods
- Switch continuity: very low resistance when closed; measure switch output change when actuated
Diagnostic algorithm
- Connect scan tool, read and record B1402 and any related codes; note freeze frame. 2) Attempt to operate driver window while observing symptoms and listening for motor/relay. 3) Check related fuses and relays; replace if blown and retest. 4) Visually inspect the driver door hinge harness and connectors for damage, corrosion or pinching; repair as needed. 5) Back-probe the switch connector and motor connector while commanding 'open': verify battery voltage on the expected terminal and correct polarity change when switching open vs close. 6) If no voltage at motor when commanded, trace wiring back to the switch and BCM: check continuity to the switch and to ground; repair open or shorted wiring. 7) If voltage is present at the motor but the motor does not run, apply fused 12 V directly to the motor terminals (observe correct polarity and safety) to verify motor function; replace motor if it does not operate. 8) If the motor runs when directly powered and wiring is good, replace or repair the driver switch. 9) If wiring, switch and motor are good but no correct driver output from the BCM, verify BCM power/grounds and CAN communication; if confirmed faulty, follow manufacturer procedures for BCM repair/replacement. 10) Clear codes and verify proper operation and that B1402 does not return. Document repairs and retest several cycles.
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Likely causes
- Damaged wiring in door jamb harness (most common for single-window failures)
- Defective driver window switch
- Failed window motor
- Blown fuse or weak/failed relay
- Corroded connector or poor ground
- Faulty BCM/window driver module (least common)
Fault status
Status
B1402 — Driver window opening circuit: circuit malfunction detected (open/short/incorrect signal).
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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