Alternator Light - Comes ON at Idle

Article No. 85-10-6


CHARGING SYSTEM - ALTERNATOR WARNING LIGHT COMES ON AT IDLE

FORD 1985 TEMPO

LINCOLN-MERCURY 1985 TOPAZ

The new "integral alternator regulator" (IAR) has a circuit that is supposed to indicate a low battery voltage condition. Under high electrical load and low engine speed (idle), the circuit can be actuated, causing the charging system warning light to turn on. This circuit was added to the regulator to warn the customer that
continued operation under a low engine speed/high electrical load condition can discharge the battery. This condition is most likely to happen at cold ambient temperatures and under high vehicle electrical load conditions and is not necessarily an indication of a charging system problem.

If the subject concern is encountered, the following diagnostic procedure should be followed to determine if a charging system failure exists:

^ Start the engine and turn on the high beam headlamps, high blower, and rear window defroster. Allow the vehicle to idle for ten minutes.

^ If the warning lamp does come on, increase engine speed to approximately 2000 RPM - the lamp should go off.

^ If the lamp does not turn off, refer to the appropriate model year Shop Manual, Section 31-01, for the complete charging system diagnostic procedure.

OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"