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Home / DTC / P0622 — Alternator FR terminal

P0622 — Alternator FR terminal

Detailed page for trouble code P0622.

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Code

P0622

MITSUBISHI P — Powertrain

Alternator FR terminal

Brand: MITSUBISHI
Type: P — Powertrain
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Page language: EN

Causes

  • Broken, pinched or shorted wiring between alternator FR terminal and ECM
  • Corroded, loose or damaged connector at alternator or ECM
  • Faulty alternator (internal regulator/FR terminal)
  • Poor battery voltage or weak battery
  • Blown fusible link or charging system fuse
  • ECM fault (rare)

Symptoms

  • Battery charging warning light (ALT/GEN) illuminated
  • Battery not charging or poor charge (low battery voltage)
  • Reduced electrical system performance, dim lights
  • Possible battery drain or no-start after extended cranking
  • Intermittent charging or erratic instrument cluster behavior

What to check

  • Scan for P0622 and any related charging codes; record freeze-frame data
  • Visually inspect battery condition and terminals; verify battery is fully charged
  • Inspect alternator and ECM connectors for corrosion, bent pins or loose fit
  • Check fuses and fusible links for the charging circuit
  • Backprobe FR terminal at alternator and ECM to observe signal/voltage with key ON and engine running
  • Perform continuity and short-to-ground/battery checks on FR wiring

Signal parameters

  • Battery voltage at main battery terminal: ~12.4–12.8 V (key off) and ~13.5–14.8 V (engine running, normal charge)
  • FR terminal: may show battery voltage or a variable/pulsed control/feedback signal depending on system — should not be open or shorted
  • Continuity between alternator FR terminal and ECM pin: low ohms (near 0 Ω to a few ohms) with circuit intact
  • Resistance to ground on FR lead: should not show a direct short to ground (OL or high resistance expected unless commanded)

Diagnostic algorithm

  1. Verify battery state of charge and health; recharge or replace if weak.
  2. Clear codes, then start vehicle and see if P0622 returns to confirm reproducibility.
  3. Visually inspect alternator and ECM connectors and wiring for damage, corrosion, or loose terminals; repair as needed.
  4. With connector connected, backprobe FR terminal at alternator and at ECM. Compare voltages with key ON engine OFF and engine running. Note differences and intermittency.
  5. Check continuity of FR circuit between alternator and ECM (with power disconnected). Repair any open/high resistance wiring.
  6. Check for short to battery or short to ground on FR lead (isolate circuit and test).
  7. If wiring and connectors are good, bench-test or replace the alternator (or perform known-good alternator swap) and retest.
  8. If alternator replacement does not clear the code and wiring is confirmed, consider ECM testing/replacement as a last step after verifying inputs and grounds.

Likely causes

  • Open or high-resistance circuit in FR lead
  • Short to battery or short to ground on FR lead
  • Internal alternator regulator failure affecting FR terminal
  • Corrosion or poor pin contact at alternator connector
  • Intermittent wiring contact from vibration or heat

Fault status

⚠️ Status
ECM detected abnormal voltage or signal on Alternator FR terminal circuit (possible open/short or alternator/regulator fault). Charging system performance may be impaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0620 P0623 P0627 P0562 P0563
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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