Code
B1322
MITSUBISHI
B — Body
Comm.error (AS P/W ECU)
Views:
UK: 10
EN: 23
RU: 22
AI status
Completed
Completed
100%
Causes
- Open or short in communication wiring (CAN or LIN) to the AS P/W ECU
- Poor or corroded connector pins at the AS P/W ECU or junctions
- Missing power or ground to the AS P/W ECU (blown fuse, loose ground)
- Faulty AS P/W ECU
- Bus termination fault (open/shorted CAN termination resistor)
- Network interference from another faulty module or aftermarket device
Symptoms
- Power windows operate intermittently or not at all for affected doors
- Related features (auto up/down, anti-pinch) disabled or erratic
- Other modules showing communication-related warning lamps or codes
- DTC B1322 stored and may reappear after clearing
What to check
- Use a scan tool to read B1322 plus any other stored network or module codes
- Check battery voltage (should be ~12–14 V) and key-on power to the AS P/W ECU
- Inspect fuses and fusible links related to power window and body ECUs
- Visually inspect connectors and wiring in door harness, hinge area and ECU connector for damage/corrosion
- Wiggle test wiring/connectors while monitoring scan tool for communication dropouts
- Measure continuity and resistance of CAN/LIN wires between the AS P/W ECU and junction/module
Signal parameters
- Battery supply to AS P/W ECU: ~12–14 V (key on)
- Ground continuity: low resistance (
- CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive); dominant state typically CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V
- CAN bus differential: ~0 V (recessive) to ~2 V (dominant) between CAN_H and CAN_L
- CAN bus termination: ~60 Ω across CAN_H and CAN_L (two 120 Ω in parallel)
- LIN bus: idle ~ battery voltage via pull-up; signal pulses to ground when active (verify with manufacturer spec for LIN)
Diagnostic algorithm
- Connect a capable scan tool. Record freeze frame, live data and any other network codes (U-codes or B-codes).
- Clear the code and attempt to reproduce. Note whether B1322 returns and under what conditions (key cycles, door movement, engine start).
- Verify power and ground at the AS P/W ECU connector with key on. Check relevant fuses. Repair any supply/ground faults before further network testing.
- Visually inspect the ECU connector and door harness (hinge area) for broken wires, pin corrosion or water intrusion. Repair or replace damaged wiring/connector.
- Perform a wiggle test on the harnesses while monitoring live network messages. If communication toggles with movement, isolate and repair that section of harness.
- Measure CAN_H and CAN_L at the AS P/W ECU connector with a DMM or oscilloscope. Confirm idle and dominant voltages and presence of valid CAN frames. Check termination resistance (~60 Ω across CAN_H/CAN_L) with power off.
- If CAN/LIN signals are absent only at the AS P/W ECU and present at other modules, suspect the ECU or connector wiring. If signals are absent across the bus, trace to common bus wiring or a failed module affecting the network.
- If wiring and bus are good, consider replacement or reflashing (per factory procedure) of the AS P/W ECU. Use known-good ECU substitution only after isolating wiring and bus issues.
- After repairs, clear codes and verify normal operation over multiple key cycles and driving conditions. Confirm no related communication codes remain.
Likely causes
- Loose/corroded connector at the AS P/W ECU
- Broken or shorted CAN/LIN wiring near door harness or hinge area
- Blown fuse or poor ground to the AS P/W ECU
- Faulty AS P/W ECU (less common than wiring/connector faults)
Fault status
Status
Communication error with AS P/W ECU — lost or corrupted network messages between the power window ECU and vehicle network.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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