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Home / DTC / P2508 — ECM/PCM Power Input Signal High

P2508 — ECM/PCM Power Input Signal High

Detailed page for trouble code P2508.

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11,451generic
22,461specific
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Code

P2508

Generic P — Powertrain

ECM/PCM Power Input Signal High

Brand: Generic
Type: P — Powertrain
Views: UK: 30 EN: 55 RU: 33
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Charging system regulator/alternator overvoltage
  • Battery overvoltage (charged incorrectly or faulty battery)
  • Backfeed from aftermarket electronics or accessories
  • Short to a higher-voltage circuit or incorrect wiring/pin swap
  • Poor or corroded ground reference at ECM/PCM
  • Intermittent connector contact or wiring damage (chafing, pin corrosion)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Stored P2508 and possibly other voltage-related codes
  • Intermittent or poor drivability (hesitation, stalling)
  • Electrical oddities (instrument gauge errors, radio or accessory anomalies)
  • Hard starting or loss of communication with ECM on scan tool

What to check

  • Read freeze-frame and stored data with a scan tool to capture voltage at fault time
  • Confirm battery resting voltage (key off), key on (engine off), and charging voltage (engine running) at battery posts
  • Visually inspect battery terminals, main fuses, fusible links, and power distribution junctions for corrosion or damage
  • Inspect ECM/PCM connector for corrosion, pin damage, or fluid intrusion
  • Check for aftermarket accessories tied to battery or ignition circuits that could backfeed power
  • Measure voltage at the ECM/PCM power input pin(s) and compare to battery voltage

Signal parameters

  • Normal battery voltage (engine off, key off): 12.4–12.8 V
  • Key ON (engine off): ~12.4–12.8 V (may rise slightly with accessories)
  • Charging voltage (engine running, normal load): 13.5–14.8 V
  • Voltage considered high: sustained readings above ~15.0–15.5 V or spikes significantly above charging range
  • Intermittent spikes can be much higher for short durations — check with a scope or data-logger

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note engine state when fault set (idle, start, load).
  2. Perform a visual inspection of battery, charging system, main fuses, fusible links, and ECM connector for obvious damage or corrosion.
  3. Measure and record voltages at the battery posts: key off, key on (engine off), and engine running. Compare to expected ranges.
  4. With scan tool connected, monitor system voltage/ECM power input parameter while revving engine and turning electrical loads on/off. Look for overvoltage conditions or spikes.
  5. Measure voltage directly at the ECM power pin(s) and ground with engine running. If directly at the module the voltage is still high, suspect charging system or backfeed; if low/normal at battery but high at module, suspect wiring or connector backfeed or pin short.
  6. Disconnect non-OEM accessories and any in-line devices that could backfeed power, then re-test. Inspect harness for pin-to-pin shorts or wire insulation breaches.
  7. Test alternator/regulator function: check for correct regulator control, diode integrity, and absence of overcharging. Replace or repair alternator if it produces excessive voltage.
  8. Check and clean all main engine and chassis grounds; measure ground resistance to battery negative. Repair as needed.
  9. If wiring and charging system check good but high voltage persists only at ECM, consider ECM internal fault — consult manufacturer tech data and consider module replacement or repair.
  10. After repairs, clear codes and perform road/idle test to confirm issue does not recur; re-scan to ensure no related faults remain.

Likely causes

  • Alternator voltage regulator failure causing sustained voltage >14.8–15.5 V
  • Aftermarket device wired to constant power feeding back higher voltage into ECM harness
  • Corroded/loose battery positive/ground or main power junction causing voltage spikes
  • Short between power circuits in harness or connector (e.g., fused circuits sharing pins)
  • Failed ECM power regulation or internal comparator

Fault status

⚠️ Status
ECM/PCM detected high voltage on its power input circuit. Condition indicates over-voltage or backfeed into module power supply; further electrical/charging system inspection required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3 hours

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Code

P2508

LAND ROVER P — Powertrain

Power input signal of the engine control module / module high power train control

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 15 EN: 36 RU: 16
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Charging system regulator/alternator overvoltage
  • Battery overvoltage (charged incorrectly or faulty battery)
  • Backfeed from aftermarket electronics or accessories
  • Short to a higher-voltage circuit or incorrect wiring/pin swap
  • Poor or corroded ground reference at ECM/PCM
  • Intermittent connector contact or wiring damage (chafing, pin corrosion)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Stored P2508 and possibly other voltage-related codes
  • Intermittent or poor drivability (hesitation, stalling)
  • Electrical oddities (instrument gauge errors, radio or accessory anomalies)
  • Hard starting or loss of communication with ECM on scan tool

What to check

  • Read freeze-frame and stored data with a scan tool to capture voltage at fault time
  • Confirm battery resting voltage (key off), key on (engine off), and charging voltage (engine running) at battery posts
  • Visually inspect battery terminals, main fuses, fusible links, and power distribution junctions for corrosion or damage
  • Inspect ECM/PCM connector for corrosion, pin damage, or fluid intrusion
  • Check for aftermarket accessories tied to battery or ignition circuits that could backfeed power
  • Measure voltage at the ECM/PCM power input pin(s) and compare to battery voltage

Signal parameters

  • Normal battery voltage (engine off, key off): 12.4–12.8 V
  • Key ON (engine off): ~12.4–12.8 V (may rise slightly with accessories)
  • Charging voltage (engine running, normal load): 13.5–14.8 V
  • Voltage considered high: sustained readings above ~15.0–15.5 V or spikes significantly above charging range
  • Intermittent spikes can be much higher for short durations — check with a scope or data-logger

Diagnostic algorithm

  1. Retrieve and record all DTCs and freeze-frame data. Note engine state when fault set (idle, start, load).
  2. Perform a visual inspection of battery, charging system, main fuses, fusible links, and ECM connector for obvious damage or corrosion.
  3. Measure and record voltages at the battery posts: key off, key on (engine off), and engine running. Compare to expected ranges.
  4. With scan tool connected, monitor system voltage/ECM power input parameter while revving engine and turning electrical loads on/off. Look for overvoltage conditions or spikes.
  5. Measure voltage directly at the ECM power pin(s) and ground with engine running. If directly at the module the voltage is still high, suspect charging system or backfeed; if low/normal at battery but high at module, suspect wiring or connector backfeed or pin short.
  6. Disconnect non-OEM accessories and any in-line devices that could backfeed power, then re-test. Inspect harness for pin-to-pin shorts or wire insulation breaches.
  7. Test alternator/regulator function: check for correct regulator control, diode integrity, and absence of overcharging. Replace or repair alternator if it produces excessive voltage.
  8. Check and clean all main engine and chassis grounds; measure ground resistance to battery negative. Repair as needed.
  9. If wiring and charging system check good but high voltage persists only at ECM, consider ECM internal fault — consult manufacturer tech data and consider module replacement or repair.
  10. After repairs, clear codes and perform road/idle test to confirm issue does not recur; re-scan to ensure no related faults remain.

Likely causes

  • Alternator voltage regulator failure causing sustained voltage >14.8–15.5 V
  • Aftermarket device wired to constant power feeding back higher voltage into ECM harness
  • Corroded/loose battery positive/ground or main power junction causing voltage spikes
  • Short between power circuits in harness or connector (e.g., fused circuits sharing pins)
  • Failed ECM power regulation or internal comparator

Fault status

⚠️ Status
ECM/PCM detected high voltage on its power input circuit. Condition indicates over-voltage or backfeed into module power supply; further electrical/charging system inspection required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3 hours

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P2507 P2506 P0563 P0562 P0627 P0628
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