So I have had a random battery light come on now and then (2000 Excursion 7.3). I have a volt meter in the cab and the fluctuations have been rare and random pinging a volt change for a second then goes away (This is a once in a while occurrence). The other day as I was driving to work and upon accelerating the meter would light up the Alt. light and drop to 12.0 and slowly go down to around 11.6. Sitting at a light in idle would take it back up to 14.2; then repeat upon acceleration and drop down. I immediately drove to have the batteries and alt. tested which came back showing no issues. I currently have a code(s) for 2 glow plug replacements that I am getting ready to remedy. Would these relate at all? (I wouldn't think so). Any advise above the ordinary testing would be appreciated.

 

Possible belt slipping...could happen under acceleration and be fine at idle. May need to watch the belt and alt. pulley when revving the engine.

 

Didnt even think abt belt. It is only 4 mos old.

 

Check the connections on the back of your alternator. If the big one is not making good contact, it may be prone to acting up.

Drake

 

If the belt is slipping on it also be sure to check the tensioner arm for proper operation. If that's the culprit throwing a belt at it won't help. Also, if you don't have the dual alternator upper radiator hose it's a messy job that you might not need to do.

I'm sure you did this, but it wasn't mentioned so I'll ask anyhow just to cover the bases. Battery connections clean and tight?

 

OK. After poking and prodding without success I finally went and bought a multi-meter...I know I should have already had one. So I did my own tests on everything top to bottom. What a big surprise to find out the alternator failed (this is the second one in 4 mos.). So I will be replacing that under warranty and all "should" be well.

 

Good deal....where do you get the alt. at¿

 

I get most of my stuff through Napa...Dad is the Electrical rep in Salt Lake City district so it comes with perks I can't pass up, but this alternator issue is becoming a hassle.

 

Might see if they offer an upgraded unit.

 

It is usually the diode on the back of the alternator that overheats. Ensure for the next one that you wire brush all wire terminals and the post they connect to. May as well go ahead and get a GPR109(for your GPR unless you have a GPCM) since dear ole dad is helping out.

 

Skip the gpr109 and go for the stancor. JMHO. I was going through a few 109's every year. I've put one stancor in and have four years on it. Same as my old truck(new owner still has it installed) and my FIL.

 

I tested GPR and it was good. But maybe I will use dear ole dad for a new one as suggested.

 

Around 97 or so, Ford came up with a voltage regulator that has a low speed charging circuit for idle and another one that took over at higher rpm. So when the alternator starts to fail, some would show a batt light at idle and others would show one at high speed until eventually it would just stay on all the time after it completely failed. The ones I always seem to find, are the ones that fail at idle and work at high speed. So that when you take it off to have it tested and they spin it up fast, and it charges.

i like the rebuild shops for alternators when they build them in house. Back when these first came out, I could not find a rebuild shop that could make these work reliably and really still have not had good luck with any of them. I do not know what it is but I had a 07 6.0 that we put one from the rebuilder on . The first one was bad out of the box, and them about every 4 months it would fail when the second was installed. Now the same places can build alternators/generators reliably for every other application you can imagine but not for the ford truck so I am not sure exactly what causes it to be so temperamental. I have run into the same issue with the ones from just about every big box retailer as well. My job puts me in contact with a lot of ford products and we usually try to use wherever is closest to our location or some companies supply their own parts.

I eventually ponied up the extra money for a FORD alternator and never had another issue with it.