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Home / DTC / C1860 — Power supply high voltage

C1860 — Power supply high voltage

Detailed page for trouble code C1860.

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C1860

MITSUBISHI C — Chassis

Power supply high voltage

Brand: MITSUBISHI
Type: C — Chassis
Views: UK: 11 EN: 17 RU: 15
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Overcharging by a faulty alternator/voltage regulator
  • Incorrect external power source applied (e.g., 24V or improper charger/jump start)
  • Short or wiring fault that feeds higher voltage into the module power pin
  • Internal failure of the module's voltage regulator or surge protection
  • Aftermarket accessories or accessory wiring incorrectly connected to ECU power
  • Corroded/loose battery or ground connections causing voltage irregularities

Symptoms

  • DTC C1860 stored; related warning lamp(s) may be illuminated
  • Erratic behavior or loss of function of the system controlled by the module
  • Blown fuses or damaged electrical components
  • Possible driveability or communication faults if other modules affected
  • Battery/charging system warning lamp or battery voltage abnormal on scan tool

What to check

  • Use a scan tool to confirm C1860 and record freeze-frame data and battery voltage at time of fault
  • Measure battery voltage with engine off and with engine running at idle (multimeter)
  • Measure voltage at the affected control module power supply pin(s)
  • Inspect battery terminals, ground straps, main fuse/fusible link and harness for damage or corrosion
  • Inspect wiring for aftermarket devices or evidence of incorrect jump/charger connection
  • Check alternator output and regulator operation (voltage and ripple), including under load

Signal parameters

  • Battery resting voltage (engine off, good battery): ~12.4–12.8 V
  • Key ON / engine OFF system voltage: ~12.4–13.0 V
  • Charging voltage (engine running, normal): ~13.5–14.8 V
  • Typical high-voltage threshold to trigger overvoltage DTC: >15.5–16.0 V (manufacturer-specific)
  • Transient/voltage spike indication: short-duration excursions above normal charging range; extreme case if connected to 24V source

Diagnostic algorithm

  1. Connect a scan tool, read and record C1860 plus any other stored codes and freeze-frame data (note measured voltage when fault recorded).
  2. With vehicle off, measure battery voltage at the battery posts and compare to expected resting values.
  3. Start engine and measure charging voltage at the battery and at the alternator output with engine at idle and under moderate load (lights/blower on).
  4. Measure voltage at the affected module power pin(s) with engine running and with accessories on to check for overvoltage or spikes.
  5. Inspect battery cables, ground straps, main fuses/fusible links and connectors for corrosion, looseness, or heat damage; repair as needed.
  6. Inspect wiring harness for aftermarket connections or signs of being connected to an improper voltage source (e.g., 24V).
  7. Test alternator/regulator operation: bench or in-vehicle test for proper regulation and diode ripple. Replace alternator/regulator if it overcharges.
  8. If voltage at module is high but alternator is normal, trace and repair short/incorrect feed or replace blown fusible link/fuse; check for internal module regulator failure.
  9. After repairs, clear codes, perform wiring/charging re-checks, then road test while monitoring voltage and ensure C1860 does not return.
  10. If the module shows physical or internal damage and wiring/charging system are good, consider module replacement per manufacturer procedure.

Likely causes

  • Alternator voltage regulator failure causing charging voltage > 15.5–16V
  • Vehicle was jump-started or connected to a charger with too high an output
  • Power feed to the affected ECU is shorted to a higher-voltage circuit
  • Failed internal power regulator or transient suppression inside the control module
  • Blown or damaged fusible link/fuse allowing unregulated voltage to module

Fault status

⚠️ Status
Control module detected supply voltage above the acceptable threshold. Code set when module input voltage exceeds manufacturer-specified limit or when an overvoltage transient is observed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0568 P0562 C1234 U0001
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Code

C1860

Other C — Chassis

PRNDL Input #3 Circuit Failure

Brand: Other
Type: C — Chassis
Views: UK: 19 EN: 31 RU: 28
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Overcharging by a faulty alternator/voltage regulator
  • Incorrect external power source applied (e.g., 24V or improper charger/jump start)
  • Short or wiring fault that feeds higher voltage into the module power pin
  • Internal failure of the module's voltage regulator or surge protection
  • Aftermarket accessories or accessory wiring incorrectly connected to ECU power
  • Corroded/loose battery or ground connections causing voltage irregularities

Symptoms

  • DTC C1860 stored; related warning lamp(s) may be illuminated
  • Erratic behavior or loss of function of the system controlled by the module
  • Blown fuses or damaged electrical components
  • Possible driveability or communication faults if other modules affected
  • Battery/charging system warning lamp or battery voltage abnormal on scan tool

What to check

  • Use a scan tool to confirm C1860 and record freeze-frame data and battery voltage at time of fault
  • Measure battery voltage with engine off and with engine running at idle (multimeter)
  • Measure voltage at the affected control module power supply pin(s)
  • Inspect battery terminals, ground straps, main fuse/fusible link and harness for damage or corrosion
  • Inspect wiring for aftermarket devices or evidence of incorrect jump/charger connection
  • Check alternator output and regulator operation (voltage and ripple), including under load

Signal parameters

  • Battery resting voltage (engine off, good battery): ~12.4–12.8 V
  • Key ON / engine OFF system voltage: ~12.4–13.0 V
  • Charging voltage (engine running, normal): ~13.5–14.8 V
  • Typical high-voltage threshold to trigger overvoltage DTC: >15.5–16.0 V (manufacturer-specific)
  • Transient/voltage spike indication: short-duration excursions above normal charging range; extreme case if connected to 24V source

Diagnostic algorithm

  1. Connect a scan tool, read and record C1860 plus any other stored codes and freeze-frame data (note measured voltage when fault recorded).
  2. With vehicle off, measure battery voltage at the battery posts and compare to expected resting values.
  3. Start engine and measure charging voltage at the battery and at the alternator output with engine at idle and under moderate load (lights/blower on).
  4. Measure voltage at the affected module power pin(s) with engine running and with accessories on to check for overvoltage or spikes.
  5. Inspect battery cables, ground straps, main fuses/fusible links and connectors for corrosion, looseness, or heat damage; repair as needed.
  6. Inspect wiring harness for aftermarket connections or signs of being connected to an improper voltage source (e.g., 24V).
  7. Test alternator/regulator operation: bench or in-vehicle test for proper regulation and diode ripple. Replace alternator/regulator if it overcharges.
  8. If voltage at module is high but alternator is normal, trace and repair short/incorrect feed or replace blown fusible link/fuse; check for internal module regulator failure.
  9. After repairs, clear codes, perform wiring/charging re-checks, then road test while monitoring voltage and ensure C1860 does not return.
  10. If the module shows physical or internal damage and wiring/charging system are good, consider module replacement per manufacturer procedure.

Likely causes

  • Alternator voltage regulator failure causing charging voltage > 15.5–16V
  • Vehicle was jump-started or connected to a charger with too high an output
  • Power feed to the affected ECU is shorted to a higher-voltage circuit
  • Failed internal power regulator or transient suppression inside the control module
  • Blown or damaged fusible link/fuse allowing unregulated voltage to module

Fault status

⚠️ Status
Control module detected supply voltage above the acceptable threshold. Code set when module input voltage exceeds manufacturer-specified limit or when an overvoltage transient is observed.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0568 P0562 C1234 U0001
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