Help with dash lights

[RustyPile]

Originally Posted by Coalkracker

If i leave the battery connected its dead within a few hours. If i disconnect it, its good for months. I unplugged the F and R plug at the alternator and it did not make a difference. Ive only visually inspected the wires under the dash to see if anything looks bad. Thats as far as ive gone so far. No testing yet.

That is a preliminary test. It determined that something IS pulling the battery down. Here's the procedure for tracking down the drain. The following is done with the ignition key in the "OFF" position. Remove one of the battery cables (doesn't matter which one) from the battery.. Using a 12 volt test light, attach the probe to either the exposed battery post or the removed cable itself (again, doesn't matter which one).. Attach the lead of the test light to the post or cable, which ever is left. The light should illuminate.. Go to the fuse box and start lifting one end of each fuse. Lift one at a time and each time take a look of the test light.. When you lift a fuse and it makes the light go out, that's the circuit that has the drain.. In some cases, the fuse protects more than one item, so here's where you'll most probably need a wiring diagram for your specific truck. You'll need to know what items are protected by each fuse. When you locate and identify each item on the offending circuit, put the fuse back in place and check the test light again. It should be illuminated again.. Disconnect each item on that circuit, one at a time, until the light goes out again.. The item, when disconnected, is the offending item..

If none of the fuses, when lifted, causes the light to go out, replace the fuses and unplug the harness at the voltage regulator. If the light goes out, you have a shorted regulator.. If the light doesn't go out, disconnect the large gauge charging wire on the back of the alternator... If the light now goes out, you have shorted diodes in the alternator.. The alternator will continue to charge (although at a reduced rate) with 1 or 2 bad diodes..