F800 series turn lights on truck shuts off

JALEGRE0

MEMBER
1999 FORD
VR6
TURBO
RWD
MANUAL
200,000 MILES

Thought it was alternator, just replaced. Truck is acting the same. Truck runs fine till you turn the lights on, once you do truck shuts off but if you shut lights back off fast it will stay started. Once off try to restart truck just makes clicking niose. Jump it, starts right back up? What do you think problem is

1 Reply

CARADIODOC

MECHANIC
33,727 POSTS

Sounds like you're not getting enough output current from the generator. That can be due to one defective diode of the six. You may also be getting no output at all. There's three possible causes for that. First observe the operation of the "battery" warning light on the dash. If it turns on with the engine not running, that circuit is working. If it stays on with the engine running, suspect a blown 15 amp fuse. If it goes off with the engine running, suspect a blown fuse link or fuse link wire between the output terminal and the battery positive terminal.

Start by measuring the battery voltage with the engine off, then with it running, and tell me those. Next, record the wire colors in the three-terminal connector on the back of the generator, then back-probe them through the rubber seals and measure those voltages, and the voltage on the fat output wire with the engine running, and holler back with those. Also measure all of those voltages with the engine off and the ignition switch on.