Hi, I have a 1985 Ranger, 2.3L. Just recently, battery started discharging over night. I checked and find a parasitic drain with ignition key off of about 3.5 – 4 amps so I know there's something pretty wrong here (I just disconnect the battery whenever I stop now). Disconnecting the field and stator wires on the alternator drops the drain to something like 30 milliamps. Disconnecting only the battery wire to the alternator has no effect. Replacing the alternator with a remanufactured one also has no effect (surprised me because I thought the alternator was failing).

Last night while doing some of this testing, lights on the truck got noticeably brighter and a headlight burned out. I measure 18+ volts across the battery now when engine is idling, (and battery charge meter moves pretty far to right when engine is revved. I figure my voltage regulator (it's the external one) is now dead.

I can replace the regulator, and headlights and all, but I figure all these are symptoms, and somebody whos knows what they are doing (which I don't) would recognize immediately the problem.

Could anybody suggest what to test, check or fix next?

If it matters has a remanuf. engine and about 320K miles on it (I bought it new and it hasn't ever given me too much trouble)..

Thanks for any help.


Note: this post has been crossposted to the Ranger Forum

 

I would replace the regulator first. Also check the yellow wire running from the terminal "A" on the regulator up to the bat connection on the starter relay. The "A" terminal wire sends the regulator the voltage level info of the truck. If this wire has a bad connection, the voltage on the "A" terminal would drop, and the regulator would tell the alt to put out too much current.

 

And when you replace the regulator, make sure it has a good ground. Run a jumper wire from a mounting bolt to a known good ground if you have to. If the regulator isn't grounded, it can't "see" the correct voltage to know when to shut down (the overcharging). However, that won't make it stick on (the drain), so you'll still need to replace it.

 

Voltage regulator and alternator (for good measure) did the trick .....

Thanks for the help.