Hey all,

'88 7.3 automatic, fairly recent batteries and rebuilt alternator (from a parts truck of mine).
The volt gauge shows right in the middle, but today my battery light came on and stays on. The 1st time it went away when I revved it, but now stays on regardless.

Any ideas as to the problem ? electrical gremlins are a weak point for me.

 

First guess is the alternator is crapping out. Check the voltage on the large wire on the back of the alt. You should have at least 13 volts with engine running. Be carefull around the belts.

 

'that could be the case. I forgot to mention that when I start the truck, the voltage gauge stays to the left (negative) until the revs are up.

I don't have a test gauge (got to get one), but I do have another spare alternator I could try tomorrow.

 

An aftermarket volt gauge is a great thing to have.

In 23 years my amp gauge in the dash has never moved.

 

'swapped in a spare alternator today. The battery light went out, but the volt gauge on the dash still stays to the left until the truck has run for a while.

I need to buy a test gauge, and look at the 130 amp conversion .

 

Yesterday my battery light started coming on again. The alternator I changed in was from a parts truck, and untested. I had my old one bench tested at Canadian Tire - it was on it's way out. I bought a testing meter - I'm getting just over 14 volts lights off, just over 13.5 volts lights on ?? I haven't been able to get an amps reading off the alternator, can you ?
On a hunch (from other posts) I changed the voltage regulator with one from the parts truck (it looked newer and was less corroded). The battery light went out.
My in dash gauge comes up to the middle now, but draws down to the left periodically, and when lights etc are on. The old alternator I'm using may be starting to fail ?
I bought a rebuild kit from Lordco for 29.95. I'll try fixing one of my other alts for the time being. (how do you put it back together with the spring loaded brushes sticking out ?)

Anyhow, all tips appreciated.

 

Look on the altinator case on the end the brushes go in, just above the bearing there will be a small hole. The straw from a WD40 can will fit through it. Replace the brushes in the case, push the carbon brush into the holder, take the WD40 straw and push threw the hole in the case holding the brush up in the holder,and do the same with the second brush. Then put the altinator case back together. When the 4 screws holding the alt. case are tight pull the WD40 straw out.

 

As long as the batteries are disconnected, straightened out paper clips work well to keep the brushes retracted as well.

 

Thanks for the tips. Is there a way to get an amperage reading off the alternator ?