Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B29E3 — Key switch signal:long

B29E3 — Key switch signal:long

Detailed page for trouble code B29E3.

34,392codes
59brands
11,901generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B29E3

MITSUBISHI B — Body

Key switch signal:long

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

Causes

  • Stuck or mechanically damaged ignition/key switch
  • Short to power in the ignition/key switch wiring
  • Faulty starter relay or stuck relay contacts
  • Poor connector or corrosion at the ignition switch harness or body control module (BCM) connector
  • Faulty BCM/immobilizer module or software error
  • Damaged wiring (chafing, pinched, water intrusion) causing a sustained signal

Symptoms

  • Engine cranks continuously or starter stays engaged after key release
  • No-crank or intermittent crank depending on circuit behavior
  • Starter binds or does not disengage properly
  • Battery drain when vehicle is off
  • Ignition or immobilizer warning lamp illuminated on dash
  • Intermittent start/stop failures or unexpected shutdowns

What to check

  • Retrieve and record freeze-frame and all related B-codes with a capable scan tool
  • Attempt to reproduce the condition and note vehicle state (key position, engine status, temperature)
  • Visually inspect ignition switch, key cylinder (or push-button start module) and surrounding wiring for damage, corrosion or signs of heat
  • Check fuses and relays related to ignition/starter circuits; swap relay with known-good if applicable
  • Measure battery voltage before testing (low voltage may affect readings)
  • Backprobe ignition switch harness and BCM input connector while operating key to observe signal behavior

Signal parameters

  • OFF: ignition switch input typically near 0 V (ground)
  • ACC/ON: ignition switch input near battery voltage (~12 V) when activated
  • START: momentary 12 V pulse applied to starter circuit — normally a brief pulse while cranking
  • Expected START pulse duration: typically a short, momentary signal (milliseconds to a couple seconds during cranking); 'long' means the START/ignition input is held active substantially longer than a normal cranking event
  • Measure using a multimeter for steady-state voltage and an oscilloscope or graphing tool to capture pulse duration and shape

Diagnostic algorithm

  1. Confirm code and note any related DTCs; clear codes and attempt to reproduce to verify persistence
  2. Inspect ignition switch area, connectors and wiring for visible damage or contamination
  3. Check and record battery voltage; ensure supply is healthy before active tests
  4. With connector backprobed, operate key through positions while observing voltage on the ignition/START input at the BCM and at the switch end — compare behavior to expected transitions
  5. Use oscilloscope or graphing scan tool to capture the START pulse during cranking and note pulse width and whether it remains high after key released
  6. If START signal stays high at the BCM but is correct at the switch, inspect harness between switch and BCM for short to power or wired fault
  7. If START signal is incorrect at the switch, remove and test the ignition switch; bench-test replacement if available
  8. Check starter relay operation and replace or swap with known-good relay to rule out stuck relay
  9. Inspect/replace damaged wiring, repair corroded connectors, and ensure good grounds
  10. If wiring and mechanical parts OK, test/replace BCM or immobilizer module per manufacturer guidance (often last resort)
  11. After repairs, clear codes and verify normal operation under the same conditions that set the code

Likely causes

  • Ignition switch contact welded or stuck in START/ON position
  • Starter relay contacts welded closed or relay stuck energized
  • Pinched harness near steering column causing short to battery
  • Corroded connector at ignition switch or BCM causing intermittent/continuous signal
  • BCM input driver damaged or faulty

Fault status

⚠️ Status
Key switch signal: long — the ignition/key input was detected active for longer than expected; possible stuck switch, wiring short, relay or module fault.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

B29E0 B29E1 B29E2 B29E4 B29F0
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 .