im about to shove this truck off a cliff (however with my luck it would drive itself back to me) i have a 91 half ton with the 300 and 4 on the floor, recently i took out my dash to do a giant clean up job, i put everthing back together as i found it, about 36 hours later the headlights were getting dim and the truck was running odd, i determined it must be the alternator, so i took it in to have it tested, it tested at 9 volts (clearly not enough) got a new alternator, problems persist!!!!!!!!!!!!!!! help!!!!!!!!!!!! i checked all the alternator wiring

the truck stays at about 12.6 volts and idles/runs on about 12.4..... help me, the baterry slowly drains and ... ugh i just wanna run this thing off a cliff

 

Check the wiring pigtail just behind the headlamp switch, and check the wiring pigtail at the alternator especially the one at the alt. as they actually reccomend replacing that harness (Major shorting issues that actually created fires) when changing an alt during that generation Ford truck....

 

sorry i didnt see that you checked the wiring to the alt, .... check that plug really well as the plug is the actual issue as the wires short inside the plasit connector..

 

ok... i've got a new plastic connector, i'll re-splice the wires and hope for the best, be back in a few with results

 

well that did absolutely nothing, battery still slowly but surely drains while its running

 

may want to have the battery checked out too i ran into the same problem with my hunting truck started fine but let it set for 6 or 8 hours nothing have to jump it off now theres a new battery place problem fixed

 

I have some electrical troubleshooting help here;
Ford Truck Enthusiasts Forums - Grubbworm's Album: Troubleshooting help, for anyone that needs it.

Just let me know if it helps.

 

just checked the battery, its more than good, the guy at the parts store gave me a plug he says goes bad alot, i will replace that later, and if that doesnt work i will definitely check out that thread grubbworm

 

well, figured out the problem, and youll never guess what it was, one of the plugs behind the gauges that controls the left side, wasn't plugged in all the way!!!!!!!!!!!!!!!!!!!!! and thats what was causing my battery not to charge!!!!!!!! can you believe that?!?!?!?!?!?! oh well, its fixed now

 

thats normally how it goes, it's something small that will affect the biggest things and you look around forever trying to find it and when you do your like wow....really? anyways nice job dude, glad to hear it's back up and running.

 

of course it is, with all this computerized stuff ARGH!!!!