P1594

Tests 21 - 25:

Tests 26 - 27:

SYMPTOM
P-1594 CHARGING SYSTEM VOLTAGE TOO HIGH

WHEN MONITORED
With no other charging system codes set. With the ignition on and engine running above 1500 RPM.

SET CONDITION
The battery sensed voltage is 1 volt below the charging system goal for 25 seconds. The PCM senses the battery voltage, turns off the field driver and senses the battery voltage again. If the voltages are the same, the code is set.

POSSIBLE CAUSES
- Generator field driver circuit short to ground
- Generator shorted
- Powertrain control module defective
- PCM defective (battery temperature)
- PCM defective (charging voltage)