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Home / DTC / B1089 — A/M DMPR.motor driver (open)

B1089 — A/M DMPR.motor driver (open)

Detailed page for trouble code B1089.

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Code

B1089

MITSUBISHI B — Body

A/M DMPR.motor driver (open)

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or disconnected wiring in the damper motor supply/ground circuit
  • Corroded or bent connector terminals at actuator or control module
  • Blown fuse protecting HVAC/actuator circuit
  • Failed damper motor (actuator) internal winding open
  • Failed motor driver transistor or control module (HVAC control unit)
  • Damage from water ingress or physical impact

Symptoms

  • HVAC mode/airflow doors do not move or stuck in one position
  • Incorrect vent selection (floor/face/defrost) or inability to change vent mode
  • Unusual clicking or no sound from damper actuator when re‑positioning
  • Climate control system stores fault codes and may display an error
  • Reduced or improper cabin temperature control

What to check

  • Confirm DTC B1089 stored and any related HVAC/actuator codes
  • Visually inspect connector and wiring to the damper actuator for damage, corrosion, or disconnection
  • Check fuses related to HVAC/actuator circuits
  • Measure supply voltage to the actuator connector while commanding damper movement
  • Measure resistance of the actuator motor windings (compare to expected or check for open/infinite)
  • Perform actuator operation test from HVAC control (if available) and listen for movement

Signal parameters

  • Expected: battery voltage (~12 V) present at motor supply pin when actuator is commanded
  • Expected: ground or PWM return present at motor ground/pulse pin during command
  • Actuator coil resistance: typically low ohms (open = infinite resistance)
  • If driver is PWM: observe pulsed output from HVAC control module when commanding damper
  • No supply or infinite resistance indicates open circuit or blown fuse

Diagnostic algorithm

  1. Read and record DTC(s) and freeze data with a capable scan tool; clear codes and re-run to confirm repeatability.
  2. Visually inspect damper actuator wiring and connector for corrosion, disconnected terminals, pin damage, or water intrusion.
  3. Check related fuses and relays; replace any blown fuses and retest.
  4. With connector disconnected, measure actuator coil resistance. If infinite/open, replace the actuator.
  5. Reconnect and backprobe the actuator harness. Command the actuator from the HVAC control and measure supply voltage and ground/PWM at the connector.
  6. If supply voltage is present but actuator does not move, bench-test the actuator directly with 12 V to confirm motor operation; replace if it fails.
  7. If actuator is good but no driver output or no voltage from module, inspect wiring continuity between HVAC control and actuator. Repair any open/shorted wires and corroded connectors.
  8. If wiring is good and actuator still not driven, suspect failed HVAC control/module driver. Verify by measuring module output with scope or substitute known-good module where practical.
  9. After repair, clear codes and verify proper damper operation through full range and confirm no recurrence of B1089.

Likely causes

  • Open wiring or poor connector making no supply/ground to the damper motor
  • Actuator motor coil open (internal break)
  • HVAC control/module driver output failed (open)
  • Blown fuse or poor ground common to the HVAC system

Fault status

⚠️ Status
Open circuit detected in A/M damper motor driver circuit — no continuity or no driver output to HVAC damper actuator.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

B1088 B1090 B10A0 B10B0 B10C0
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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