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Home/DTC Codes/Ford/Explorer/2002-2005 4.6L V8/P1633
P1633

Keep Alive Power Voltage Too Low

2002-2005 Ford Explorer 4.6L V8 🇨🇦

Moderate SeverityPowertrain

Description

The PCM has detected that the Keep Alive Power (KAPWR) voltage is too low. This immediately illuminates the MIL and means the PCM cannot maintain its adaptive learning values. The KAM circuit should maintain battery voltage at all times.

Symptoms

  • Check Engine Light (immediately on)
  • Engine may not start
  • Poor idle quality
  • Harsh transmission shifts
  • Loss of all adaptive values

Common Causes

  • Corroded battery terminals or cables
  • Faulty PCM power relay
  • Blown KAM fuse
  • Discharged battery
  • Excessive parasitic draw depleting battery
  • Wiring issue in KAPWR circuit

Diagnostic Steps

  1. Check battery voltage (should be >12.4V key off)
  2. Inspect battery terminals for corrosion
  3. Check KAPWR fuse
  4. Test PCM power relay
  5. Test KAPWR circuit voltage at PCM connector
  6. Check for parasitic battery draw

Repair Notes

Clean battery terminals. Replace KAPWR fuse. Replace battery if discharged. Repair wiring.

Related Codes

P1600Loss of KAM Power — Open CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1600ECM Battery Backup CircuitP1600Loss of KAM Power Circuit OpenP1600ECM Battery Backup CircuitP1600ECM Battery Backup CircuitP1600Loss of KAM Power — Open CircuitP1600Loss of KAM Power — Open CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1600PCM Battery Direct Power CircuitP1605PCM Keep Alive Memory Test FailureP1605Knock Control CPU MalfunctionP1605PCM Keep Alive Memory Test FailureP1605PCM Keep Alive Memory Test ErrorP1605PCM Keep Alive Memory Test FailureP1605A/T Diagnostic Communication LineP1605Knock Control CPU MalfunctionP1605A/T Diagnostic Communication LineP1605Knock Control CPU Malfunction

Other Powertrain Codes

P1633 on Other Vehicles

Ford Aerostar

1990-1997 3.0L V6

Ford Aerostar

1990-1997 4.0L V6

Ford Bronco

1990-1996 4.9L I6 300

Ford Bronco

1990-1996 5.0L V8 302 Windsor

Ford Bronco

1990-1996 5.8L V8 351 Windsor

Ford Bronco

2021-2024 2.3L I4 EcoBoost

Ford Bronco

2021-2024 2.7L V6 EcoBoost

Ford Bronco Raptor

2022-2024 3.0L V6 EcoBoost

Common Questions

What does code P1633 mean on a 2002-2005 Ford Explorer?

P1633 stands for "Keep Alive Power Voltage Too Low". The PCM has detected that the Keep Alive Power (KAPWR) voltage is too low. This immediately illuminates the MIL and means the PCM cannot maintain its adaptive learning values. The KAM circuit should maintain battery voltage at all times.

What are the symptoms of P1633 on a Ford Explorer?

Common symptoms of P1633 include: Check Engine Light (immediately on), Engine may not start, Poor idle quality, Harsh transmission shifts, Loss of all adaptive values.

What causes P1633 on a 2002-2005 Ford Explorer?

Common causes of P1633 include: Corroded battery terminals or cables, Faulty PCM power relay, Blown KAM fuse, Discharged battery, Excessive parasitic draw depleting battery, Wiring issue in KAPWR circuit.

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