1998 Ford Ranger electrical system

BRIAN RANGER98

MEMBER
1998 FORD RANGER
3.0L
V6
2WD
AUTOMATIC
250,000 MILES

Instantly blowing generator voltage regulater fuses every time I change it. The alternator was charge when I first found that the generator voltage regulater fuse was blown and I changed it and it was charging good and the battery light went off in the dash. But a few hours later it blew it again and now it's blowing that fuse instantly. Any idea where the short could be or other possible fixes? Please?

1 Reply

CARADIODOC

MECHANIC
33,741 POSTS

A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

I assume it's a blue 15 amp fuse. If it is, that feeds the voltage regulator and the field winding on the yellow wire in the generator's plug. That circuit remains live all the time, and there is very little that can short and blow the fuse. Most of what can short will cause a drain on the battery, but not a blown fuse. That leaves the yellow wire itself. If I'm right, the short will still be there when you unplug the connector. The ignition switch doesn't even have to be on. Follow that wire back to see if it is rubbed through someplace and touching the body.

If the short DOES go away when you unplug the connector, suspect the voltage regulator. That would not be common.