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Home / DTC / C1340 — Stop lamp switch

C1340 — Stop lamp switch

Detailed page for trouble code C1340.

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Code

C1340

MITSUBISHI C — Chassis

Stop lamp switch

Brand: MITSUBISHI
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Defective stop lamp (brake) light switch
  • Incorrect switch adjustment or misalignment
  • Damaged wiring or broken conductor in switch circuit
  • Corroded, loose or disconnected switch connector
  • Blown fuse or poor fuse connection affecting brake switch circuit
  • Faulty body/ABS/BCM module input or poor ground

Symptoms

  • Brake lights do not illuminate when pedal is pressed
  • Brake lights stay ON continuously
  • ABS, VSC/ESP or traction control warning lights set
  • Cruise control may not engage or may disengage immediately
  • Shift interlock or starter interlock (no start unless brake pressed) malfunction
  • Diagnostic trouble code C1340 stored and may be accompanied by other related codes

What to check

  • Visually inspect brake light bulbs and fuses for the brake lamp circuit
  • Check switch location at brake pedal for physical damage and correct alignment
  • Operate the pedal while watching the stop lamps (verify on/off behavior)
  • Inspect the switch connector and wiring for corrosion, loose pins, chafing or breaks
  • Use a scan tool to read live data for the stop lamp switch/BRK signal while actuating the pedal
  • Measure voltage/continuity at the switch connector with connector plugged/unplugged according to vehicle wiring (verify expected values)

Signal parameters

  • Typical switch behavior: open when pedal released, closed when pedal pressed (or vice versa on some models)
  • Continuity: closed ≈ 0–1 ohm, open ≈ OL/infinite (vehicle‑specific)
  • Voltage: signal may be switched battery voltage (approx. 12–14 V when active) or a low‑voltage logic reference (≈5 V) depending on vehicle — consult service manual
  • Scan tool parameter: brake switch status (ON/OFF) should change state immediately when pedal is actuated

Diagnostic algorithm

  1. Confirm symptoms and retrieve freeze frame/related codes with a scan tool; note other modules affected.
  2. Inspect brake lamp bulbs and relevant fuses; replace if necessary and retest.
  3. Visually inspect the stop lamp switch at the pedal for secure mounting, correct plunger travel and obvious damage.
  4. Operate pedal while observing brake lamps; if lamps don’t behave correctly, suspect switch or wiring.
  5. Disconnect the switch connector. With ignition ON, backprobe the connector and measure reference voltage and ground presence. Compare to factory service values (12 V or 5 V reference).
  6. Check continuity of the switch: measure resistance across switch terminals while actuating pedal (closed ~0 Ω, open =∞). If readings are out of spec, replace the switch.
  7. If switch tests good, trace wiring to the control module: inspect for opens/shorts, repair damaged wiring, and verify connector pins.
  8. Check module grounds and power supplies if wiring is sound. If module inputs are not behaving and wiring is good, consider module fault or need for module reprogramming/calibration.
  9. After repairs, clear codes and perform functional test cycles (operate pedal, confirm lamp and module responses) and re-scan for reappearance of C1340.

Likely causes

  • Failed stop lamp switch (most common)
  • Connector corrosion or bent terminal causing intermittent contact
  • Switch plunger out of position (ride height change, pedal pad moved)
  • Short to battery or ground in the switch wiring
  • Module input circuit fault or poor ground at module

Fault status

⚠️ Status
Stop lamp switch circuit malfunction — missing, stuck or out‑of‑range stop lamp switch signal.
🟢 Repair difficulty: Easy
⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

P0571 P0572 C1201 U0121 C1350
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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