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Alternator light ON with KEY OFF[240-260/83] posted by Rick on
Wednesday, 22 July 1998, at 6:31 p.m.
In my 1983, 245 Turbo I am having a unusual problem.
After the ingnition is switched OFF the Alternator light comes on!!! The first few times this happend the light went off after a few (5-10) min. Now it stays on for hours and drains the battery. Any ideas? My thoughts are either a wiring short or a Bad regulator.
I have had the charging system checked out and all seems to be in working order.
An additional piece to the puzzle about 3-4 wks earlier the "BRIGHT" indcator light stopped working. Any connection?
Thanks
--
Rick
Re: Alternator light ON with KEY OFF[240-260/83] posted by abe crombie on
Wednesday, 22 July 1998, at 11:41 p.m.
Your rectifier diodes in alternator are faulty.
Take an AC voltmeter with it running and check for AC voltage, anything over 25 millivolts AC indicates bad rectifier diodes.
One of them is shorted and when you switch off key it is backfeeding through regulator circuit to alt light wire terminal and then feeding into cluster, with key off the other bulbs all combined provode enough of a ground path to light bulb. The alternator will pass a simple voltage output test but would fail an amperage (load) test if the diode(s) is (are) faulty. The remaining 2/3 of alternator is working when one of the diodes fail. Battery will stay up unless you drive slowly and have a lot of things on like lights and fan at same time.