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Discussion Starter · #1 ·
question for allt the 68 owners out there I have roughly an 800 millivolt drain with key off (.8V) Way too high. I finally got my service manual for this year car and have found the solution and another problem. The drain seems to be the voltage regulator. I have batt voltage going in on the orange wire. A .4V drop coming out at terminal F. An another .4V loss at the alternator. I know how to take care of the regulator to alt. problem. WHen checking thew wiring diagram, It showed that the regulator was grounded to the chassis only. Yet in the regulator testing section, it showed a ground at the regulator, and a wire going to ground on the alternator. Was just wondering if the extra wire is nonexistent or i really need it. If i Can find any extra wire laying around i will loosely run it just to see if anything changes.
 

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The alternator is grounded through it's case. You usually don't need a ground wire connected to it unless the brackets aren't making the ground connection. In either case, the alternator ground wouldn't cause a current or voltage flow to be going through the regulator when the engine is off.

Peter
 

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Sounds like you have a bad diode in the alternator. For some reason most alternator shops will tell you the alternator is good if it will charge, but never check for bad diodes.
 

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Discussion Starter · #4 ·
not sure about the diode. Vehicle had a drain when i bought it. I swapped out the alternator for a new one because of a crack in the ear. Still draining.
 

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Tried disconnecting the main harness wire off the horn relay? This will separate all the items inside the car and the headlights from the charging circuit. Leaves pretty much only the alternator, regulator, horn relay, and junction block behind the battery in the circuit. Should tell you if it's the regulator or not.
 
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