P1594moderate severityPowertrain
Charging System Voltage Too High
on 1997 Jeep Wrangler 4.0L I6 · 4WD
What this code means
The PCM has detected that the charging system voltage is above the acceptable range. The voltage regulator in the alternator is allowing excessive voltage, which can damage electrical components and boil battery electrolyte.
Symptoms
- Check Engine Light
- Battery warning light may illuminate
- Electrical components failing prematurely
- Battery swelling or leaking
- Headlights excessively bright
Common causes
- Faulty voltage regulator in alternator
- Poor ground connection at alternator
- Corroded battery cables
- Faulty PCM voltage sense circuit
- Wiring issue in charging circuit
Diagnostic steps
- Measure charging voltage at battery with engine running (should be 13.5-14.8V)
- Check alternator ground connection
- Inspect battery cables and terminals for corrosion
- Test voltage regulator function
- Check PCM voltage sense wire
Repair notes
Replace the alternator if the voltage regulator is causing overcharging.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1