5 XF 95 series Alternator DIAGNOSTICS 2. ALTERNATOR 2.1 FAULT-FINDING TABLE 1 200303 2-1 SYMPTOM: ALTERNATOR NOT PRODUCING POWER WHEN IDLING Possible cause Remedy - Open circuit in connection 15 on alternator - Connection 15 on alternator short-circuited to earth - Internal defect Repair connection 15 Repair connection 15 Replace regulator SYMPTOM:
ALTERNATOR WARNING (YELLOW) Possible cause Remedy - Open circuit in ‘S’ connection - Open circuit in ‘L’ connection - Open circuit in connection 15 - Voltage difference between ‘B+’ and ‘S’ connections greater than 2.5 V - Voltage too low Measure the regulated alternator voltage with as many consumers as possible switched on and with the engine turning above idling speed Check/repair wiring Increase the engine speed to approx. 1500 rpm. If voltage is now present, check connection 15 on the alternator Check all contacts between alternator and batteries (contact resistors). Internal battery resistance too high Check alternator drive. Check wiring on contact resistors.
Check regulated voltage Replace voltage regulator SYMPTOM: ALTERNATOR VOLTAGE HIGH (RED) Possible cause Remedy - Voltage too high > 31 V - Internal defect Measure voltage Replace regulator/alternator