ALTERNATOR OVERCHAGING

My alternator is charging at a rate of 16.9v at idle 800rpm my battery is reading 12.4v so that's right but I thought 16.9 was high could there be an issue?

the reason I checked it was that the battery charge light came on in the dash. it sounds to me like the regulator board might be bad.

anybody have any idea's

Yeah that seems high, looks like its time to replace it. 15V+ is too high, roughly 14.7V is the highest you should see. Hope it doesn't fry anything.

there is a regulator board on these trucks right?

I didn't see anything that looked like it anywhere?

I believe that you'll need a complete new alternator.

I once had a 1979 Toyota truck and one day all the lights got bright and burned out except for headlights and flashers. So I had to replace bulbs as well as alternator (and that may have had a separate regulator too, can't remember).

The voltage regulator is internal, its a complete unit. Get a new one or swap to a more powerful one like a GM alt.

thanks I appreciate it.

Found a reman for about 85 so im gonna do that.

Don't condemn the alternator before having the battery load tested!
Bad batteries can cause all sorts of goofy gremlins.

Ive never done a load test on a battery. ill have to youtube that one. I checked the battery (two months old by the way and not a cheepy) and it was showing 12.4 with the truck off. I have until Friday when the new alt gets here so ill do a load test.

I have to use it for the short 10 min drive to work and back but I won't drive it other than that until I get the new one in.

I hope nothing fries up on me.

I think you have a bad battery. Or maybe on the outside, a bad cable that is corroded internally. Replacement cable ends are a place for trouble on 20+ old trucks. Given that your battery is only two months old it should be showing more than 12.4 volts. I'm thinking you have a dead cell and the alternator is trying to push voltage past the dead cell. Or the corrosion in the cable. Each cell in a 12 volt battery at discharged state should be 2.1 volts (2.1 x 6 = 12.6) and the alternator is going crazy trying to get the battery to 13.6.~ 14.2. All the extra voltage building up in the alternator is being bled off as heat and that will take out the alternator.

With the engine off, you can do a simple load test by turning on every electrical draw for about three-five minutes and checking your voltage. What that does is drop off the surface charge to something a little more normal for the battery, I think you're going to see the voltage drop to around 11 VDC on yours, a sure sign that the battery has a weak cell.

Hope this helps.

Most chain parts stores will load test the battery for free. A decent shop may also do it for nothing.
Call around.