Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P1803 — Automated-M/T Fail(gear bridge)

P1803 — Automated-M/T Fail(gear bridge)

Detailed page for trouble code P1803.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P1803

MITSUBISHI P — Powertrain

Automated-M/T Fail(gear bridge)

Brand: MITSUBISHI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty gear-bridge actuator, motor or shift solenoid
  • Damaged or corroded wiring or connector to transmission sensors/actuators
  • Faulty transmission range/gear position switch
  • Low, contaminated, or incorrect transmission fluid
  • Mechanical obstruction, worn linkage, or internal transmission damage
  • Poor battery/charging system voltage or grounding

Symptoms

  • Transmission warning lamp or TCM fault indicator illuminated
  • Unable to select gears or transmission stuck in one gear (often limp mode)
  • Erratic or incomplete shifts, delayed engagement
  • No vehicle movement when a gear is selected
  • Unusual noise during attempted gear changes (grinding, buzzing)
  • Related drivability faults, reduced power or loss of selectable gears

What to check

  • Read all stored and pending trouble codes and freeze-frame data from both ECU and TCM
  • Check battery voltage and engine ground integrity
  • Inspect transmission fluid level and condition (color, smell, contamination)
  • Visually inspect connectors and wiring to TCM, gear position switches, actuators and solenoids for damage/corrosion
  • Scan real-time data: gear position, commanded gear, actuator status, motor current, CAN bus status
  • Attempt to actuate gear bridge/shift actuator via factory scan tool and observe response

Signal parameters

  • Battery / supply voltage: ~11–14.5 V (stable during cranking and operation)
  • Gear position switch / sensor: expected switching signals within 0–5 V range (refer to service manual for exact thresholds)
  • Actuator motor/solenoid coil resistance: typical low-ohm value (measure and compare to factory spec)
  • Actuator motor current draw: should be within manufacturer specified range — excessive current may indicate binding or stalled motor
  • CAN / serial comms: normal message traffic between TCM and ECM (no timeout errors)
  • Transmission fluid pressure (if monitored): within spec for engagement and gear changes

Diagnostic algorithm

  1. Retrieve all diagnostic codes from the TCM and engine ECU, note freeze-frame and related codes.
  2. Confirm battery condition and ground connections to ensure valid test data.
  3. Inspect wiring and connectors for the gear position sensor/actuator for corrosion, looseness, chafing, or water ingress; repair as needed.
  4. Check transmission fluid level and condition; correct level or replace fluid if contaminated per service procedure.
  5. With scan tool, monitor commanded gear vs. actual gear/position sensor while attempting gear changes; note discrepancies.
  6. Command the gear-bridge actuator/shift motor from the scan tool (if supported) and observe mechanical response and listen for motor operation.
  7. Measure actuator/solenoid coil resistance and motor current while commanding the device; compare to factory values. High current or stalled motor indicates mechanical binding.
  8. Inspect and manually operate external shift linkage (with engine off) to detect binding or seized components; free or replace worn linkage parts.
  9. If electrical checks pass but actuator fails to move under command, remove and bench-test the actuator/servo per service manual. Replace if faulty.
  10. If actuator and linkage are operable but fault persists, investigate TCM software/calibration and CAN communications; check for updates or TCM replacement per Mitsubishi guidance.
  11. After repairs, clear codes, perform relearn procedures (if required), and road-test while monitoring transmission parameters to verify proper operation.
  12. Safety note: Secure vehicle, use supports, and follow manufacturer procedures when working under the vehicle or testing driveline components. Avoid driving if transmission is in limp mode or gears are unreliable.

Likely causes

  • Intermittent or open/shorted wiring to the gear-bridge actuator or position switch
  • Failed shift actuator (electric motor or internal gears)
  • Faulty gear position sensor (incorrect feedback to TCM)
  • Hydraulic/clutch actuator failure or insufficient fluid pressure
  • Mechanical seizure or binding in shift linkage or internal gear train

Fault status

⚠️ Status
P1803 — TCM reports automated/manual transmission gear-bridge failure. The TCM detected incorrect or missing gear engagement feedback or actuator response. Avoid extended driving; inspect wiring, fluid level, actuator and linkage, and perform diagnostic tests with a factory scan tool.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 2-6 hours

Similar codes

P0700 P0705 P0715 P0720 P0760 P0765
406

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

MITSUBISHI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .