Powertrain, generic (extended)

P2504 Charging System Voltage High

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2504 is logged when the charging output overshoots: the measured voltage rises above what the module asked the generator to produce. FCA names it Charging System Output High and publishes several cases. A 2021 Ram 1500 lit the check engine lamp after a repair, with P2504 set and P2503 stored, and the advice was to voltage-drop every circuit involved. On a 2022 Ram 1500 that would not crank, the cause was the N1 connection at the high-current fuse array plus poor grounds from battery to body and from body to engine. The Durango bulletin treats P2504 alongside P2503 and the loose B+ post. Poor connections fool the measurement, so a sound alternator can be blamed. P0563 differs: it rates the module supply. Real overcharging can boil the battery and damage electronics.

Likely causes

High resistance at B+ fuse array or ground straps distorting the reading
Regulator stuck and overcharging
Battery current or voltage sensor delivering wrong values

Symptoms

  • Check engine lamp, sometimes battery lamp
  • Very bright lights, bulbs failing early
  • No crank in connection-related cases

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–900
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

alternatorvoltage regulatorbattery

Related codes

P2502P2503P0563

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.