electrical problem.....

r0n1n · #1 (**permalink**) 06-29-2009, 08:46 PM

i've been having what i thought were problems with the alternator, where the voltage needle bounces back and forth, i just replaced the alternator and i still have the problem. only now it just seems to bounce back and forth a little but the needle never dropped to the left like before. i used a test light and there is no short in any of the circuits. the battery before starting the truck was ~12.55 but now after driving back from checker, about 15 minutes, i turned the truck off and the battery voltage is 12.98

also, when i turn the ac to max the voltage needle stops bouncing and just stays in the middle. any ideas? i read somewhere that the gauge can lose it's damping???
thanks, jason

Franklin2 · #2 (**permalink**) 06-30-2009, 09:29 AM

At night with the lights on, if they blink with the voltage gauge, then you might have a problem with the charging system. If they are steady, but the gauge still varies, it might be the gauge.

BPofMD · #3 (**permalink**) 06-30-2009, 11:04 AM

Have you checked the electrolyte level in the battery (s)?

r0n1n · #4 (**permalink**) 07-05-2009, 10:09 AM

at night the lights flicker when the gauge bounces,although i drove for 3 hours and when i stopped i tested the battery and the voltage was 12.7. so it is charging. the whole trip the gauge was bouncing back and forth.

Franklin2 · #5 (**permalink**) 07-05-2009, 12:46 PM

I don't know what year truck you have, but if you have the separate regulator system, run a ground wire from one of the regulator mounting bolts to the battery negative, and see if the problem goes away.

r0n1n · #6 (**permalink**) 07-05-2009, 04:24 PM

sorry, 97 F250 w/ 7.5L it's an internal regulator, and i just got the alternator and reg replaced. the battery was bought in march 09, but i'll get it tested to see if there's a bad cell.

Franklin2 · #7 (**permalink**) 07-05-2009, 11:44 PM

Take a jumper cable and clamp one end to the alternator housing, and the other end to the battery neg. If that doesn't make it go away, I would check the plugs on the alternator to make sure they are not melted or corroded inside. If they are ok, I would get another alternator. You will not be the first to get a bad alternator if it's a rebuilt unit.

r0n1n · #8 (**permalink**) 07-06-2009, 10:10 PM

i hooked up a cable to the alternator and to the neg battery post, no change. i've checked the plugs on the alternator and they seem fine. this is the second alternator that i've had this problem with, so i don't think it's the alternator. the last alternator i had tested fine at o'reilly but a guy was nice enough to exchange the alternator anyway. with the lights dimming and the sound it's making, it seems as if the alternator is charging in spurts. i'm at a dead end with this, any new ideas?

thanks, jason

BPofMD · #9 (**permalink**) 07-07-2009, 12:40 PM

Get another alternator.... I've seen people have to swap 'em more than twice to get a good one.