My 1999 f250 wont charge, to date we have changed and tested the alternator (x4) the battery (x3) the under hood alternator plugs and the battery terminals. tested the wire between the alternator and
My 1999 f250 wont charge, to date we have changed and tested the alternator (x4) the battery (x3) the under hood alternator plugs and the battery terminals. tested the wire between the alternator and the battery and had the same voltage both ends, also replaced the starter
Cars & Trucks
Answers & Comments
Let's start at the beginning.
When you turn the key on, you send 12 volts thru the charge light (if equipped) which triggers the alternator "on" and when the engine starts the alternator should generate enough voltage to reverse the direction of that circuit and turn the light off. If you have a volt gauge the effect is the same without having a warning light.
On some models the alternator gets its on signal from the engine computer instead of the instrument cluster.
If the alternator checks out ok on the test bench, but does not produce 13-14 volts on the truck, either the main power circuit is dead, or the alternator is not getting the "on" signal.
The three circuits involved are the large wire with a 175 amp mega fuse or fuseable link, a 20amp circuit going to the alternator, and a 10amp circuit to power the alternator "on".