Originally Posted by 77fordhighboy
I have a 77 ford F250 highboy. i love the truck but the wiring is ugly from years of jerry-riggin. my problem now is that a few weeks ago my aulternator went so i replaced it along with my battery because it was shot to, and my voltage regulator. before i put the aulternator in i had it bench tested and it put out 14.5 volts, but when i put everything on my truck and tested the voltage it was only putting out 12.1 volts, which is not enough to run my truck for long (a week or so using no accesories). i traced all my wires from my aulternator to my battery, and i even replaced my starter selinoid a few months ago. this thing has had me and everyone that has looked at it confused so if you have any info please post a thread or you could call me anytime at (412) 716-4629
I put a new reconditioned alternator on a few months back. Wired perfectly, but it just would not kick into action. Would constantly stay @ 12 volts (batter power). Double and tripple checked the wiring. Had me stumped too.
Took it back to the supplier who gladly invited me out to the workshop test bench.........see here you go mate, works perfectly.....DOH! Oh no it didn't! After stripping it down, some of the diodes had blown. He said I must have connected my battery up backwards - the day hell freezes over I did! Anyway, got a new one home and it worked fine.
So, don't spend all day doing the wiring if you wired it up the same way you removed it. Take it back and get it tested again.
As mentioned, mine needs to get upto about 1500 and sometimes 2000rpm to come on line. Try giving it a rev, then check the voltage.