Alternator Not Charging

[swampedout]

Hey folks,

Started driving the 250 and it's draining batteries. I found one small draw from the trailer brakes that the previous owner wired straight off the battery. I unplugged that for now but I went ahead and checked my voltage when the truck is running in the driveway and I had 2 batteries which tested around 12.6 when I first cranked the truck and minute by minute, they went down to 12.3 before I cut the engine off. Also did a voltage drop test across the negative post to alt. body, bracket, engine block and didn't see anything wrong.

Both of the batteries were recently charged off the vehicle.

I'm going to take the alternator in to bench test and hopefully it's just a bad unit. But because most of my problems don't seem to have simple solutions, what else can I test for? I'm not very familiar with the voltage regulator system here. Any tests I can run on it?

Thanks in advance.

[swampedout]

Here's a couple thousand more words better than I can describe this mess.

The alternator was hooked up so that the 4 wires soldered together into a red wire that connects at alternators battery position.

Then there is an orange wire that was going from one of the smaller terminals in the middle to the F connection on voltage regulator. No ground connection on alternator although there is a big negative cable on the top of the alternator bracket

[85lebaront2]

Ok, first item, alternators, unless they are mounted in non-conducting bushings like my Chrysler, ground through the case to the mount bracket. The wires connected together, if it looks as though they are welded, that is a factory splice, it probably had friction tape on it or was potted in something originally (Detroit was changing a lot of wiring methods in the 80s and 90s.

That alternator looks like one of the 60 or 90 amp side terminal style know as a 1G for 1st generation which uses a remote (fender mounted) regulator rather then the integral regulator of the 2G and 3G designs. It is not a super difficult conversion to a 3G 130 amp unit from a Taurus 3.8L V6.

Does your truck have an ammeter? Full gauge package had that and was also built with a tachometer option.

[swampedout]

Ok, first item, alternators, unless they are mounted in non-conducting bushings like my Chrysler, ground through the case to the mount bracket. The wires connected together, if it looks as though they are welded, that is a factory splice, it probably had friction tape on it or was potted in something originally (Detroit was changing a lot of wiring methods in the 80s and 90s.

That alternator looks like one of the 60 or 90 amp side terminal style know as a 1G for 1st generation which uses a remote (fender mounted) regulator rather then the integral regulator of the 2G and 3G designs. It is not a super difficult conversion to a 3G 130 amp unit from a Taurus 3.8L V6.

Does your truck have an ammeter? Full gauge package had that and was also built with a tachometer option.

Truck does have ammeter and tach. Ammeter seems to work. It sticks up at halfway mark.

A lot of the wiring is definitely not factory so it would be nice if that one splice is. Its the only soldering ive seen so far. PO seemed to use butt splices and crimp connects.

The red power wire will spark when it touches the alt case so I think I have power to it and a good circuit to negative.

So either alt is bad, regulator is bad or regulator wiring is bad?

[ArdWrknTrk]

Truck does have ammeter and tach. Ammeter seems to work. It sticks up at halfway mark.

A lot of the wiring is definitely not factory so it would be nice if that one splice is. Its the only soldering ive seen so far. PO seemed to use butt splices and crimp connects.

The red power wire will spark when it touches the alt case so I think I have power to it and a good circuit to negative.

So either alt is bad, regulator is bad or regulator wiring is bad?

There is always the EVTM in the Resources folder for step by step diagnostics of the alternator and voltage regulator.

[swampedout]

There is always the EVTM in the Resources folder for step by step diagnostics of the alternator and voltage regulator.

Thanks, I need to spend more time looking through the resources in this website. Sorry for not looking there first.

But luckily I think me and the old process of elimination might have solved the problem. Replaced the regulator and batteries were charging on idle. I let the truck run for a couple minutes and saw the batteries go up to 13+ so I'm happy for now. Glad I didn't have to get further into the wiring. The Gr stator wire goes from the regulator to the cab (and presumably ammeter?) and no stator wire is needed on the alternator itself. I still have a lot to learn.

Thanks for your help.

[ArdWrknTrk]

Thanks, I need to spend more time looking through the resources in this website. Sorry for not looking there first.

But luckily I think me and the old process of elimination might have solved the problem. Replaced the regulator and batteries were charging on idle. I let the truck run for a couple minutes and saw the batteries go up to 13+ so I'm happy for now. Glad I didn't have to get further into the wiring. The Gr stator wire goes from the regulator to the cab (and presumably ammeter?) and no stator wire is needed on the alternator itself. I still have a lot to learn.

Thanks for your help.

I hate to say "look at the manual" but I was under a van changing calipers.

There are two ways the 1G was wired.

If you had a light instead of a ammeter, the green/red wire would indeed excite the alternator.

Glad a simple regulator swap seems to have fixed your problem.

Edit: The ammeter has red/orange wires.

I believe the green/red wire is key on power.

[Gsmblue]

Thanks, I need to spend more time looking through the resources in this website. Sorry for not looking there first.

But luckily I think me and the old process of elimination might have solved the problem. Replaced the regulator and batteries were charging on idle. I let the truck run for a couple minutes and saw the batteries go up to 13+ so I'm happy for now. Glad I didn't have to get further into the wiring. The Gr stator wire goes from the regulator to the cab (and presumably ammeter?) and no stator wire is needed on the alternator itself. I still have a lot to learn.

Thanks for your help.

That 4 way splice looks like mine did. I pulled it apart and resoldered it.

Anyhow. Both my trucks had issues at the same time. One was a bad voltage regulator on the fender and the other was the alternator.

Once you bench test the alternator you will know!

[Danny G]

That 4 way splice looks like mine did. I pulled it apart and resoldered it.

Anyhow. Both my trucks had issues at the same time. One was a bad voltage regulator on the fender and the other was the alternator.

Once you bench test the alternator you will know!

I had a similar problem, required a whole new wire run practically, new crimps, environmentals etc. I'm glad yours was a quick fix but it looks like it wouldn't hurt to start thinking about redoing that wiring, or at least protecting the exposed stuff.

[swampedout]

I had a similar problem, required a whole new wire run practically, new crimps, environmentals etc. I'm glad yours was a quick fix but it looks like it wouldn't hurt to start thinking about redoing that wiring, or at least protecting the exposed stuff.

Yea I knew when I bought this truck that the wiring was going to be a project. Im going through it bit by bit.