hey guys whats up, i have a 1986 dodge b-150 custom van, it has a 3.7 litre 225 slant six engine in it with an automatic transmission backing it up

yestreday as i was coming home from the store, i noticed(via the amp meter) that the alternator was no longer chargeing, the turn signals were labored(blinking very slowly, also the indicators were extremely dim) the headlights and dash lights were fading fast, luckily i was able to get it home okay.

4 months prior the same thing happened only i had to nurse it home 10 miles in the dead of night with no lights, heat or otherwise.
that time i had purchased a new alternator as well as a new voltage regulator and the problem was solved

this time i thought mabey the voltage regulator had quit on me again so i bought a new one, no such luck, so i figured mabey the alternator had quit, yeah i know it was new but when i first installed it it made a whiring noise, made the van sound like an old military jeep,which didnt sit right with me, so i brought it back and exchanged it for another one, still no gettin any juice i checked the field connections from the voltage regulator to the alternator with my ohm meter and they checked out just fine, i even brought the new alternator, as well as one i had gotten from the junk yard, to autozone to be tested ,they both passed.
the alternator is being run through one of those sun pro gauges, so i checked powerflow through the gauge with my ohm meter and it was just fine, but still could the gauge be defective?
how bout the wiring going through the gauge? thats about the only thing that i hadnt checked yet
i also ran another test, i losend the negative battery cable and started the van, i then pulled the cable off the battery while the motor was running and the motor cut out, which means the engine is running off the battery right? shouldnt it be running off the alternator? what could this be?
what the heck is going on here?

 

I was led to believe if one disconnected the battery while the engine is running the diodes in the alternator go POOF!!

Other things to check are the battery connections, don't just look but remove them and make the lead look like silver.

Battery to engine ground.
Engine to frame ground
battery to firewall ground.

There are some fusible links stuffed behind the brake booster. One if these bridges the alternator and battery. Find it and check it.

Some voltage regulator cases must be good and grounded before and after reconnecting the battery.

 

I KNEW IT!, well ill have to check those links, i looked at the wiring diagram the book i have provided me with didnt show any fuseible links, so i didnt think that was a possibility. ill check behind the brake booster, hopefully i find the links. ill keep yyou posted after im done today.

 

OH, and i made a ground strap the last time i did the voltage regulator, grouned it to the battery, and aparently the diodes are fine had the alternetor checked after i did that.

 

NO LUCK!, i replaced every single fusible link behind that booster and as i cut them out i checked them for continuity and they all passed NOTHING CHANGED. i even changed the regulator out with one of my other new ones!! i spent all day on this, i checked all the fuses, im defienttly missing something here
the alternator passed at autozone so thats not it
the regulators are all new, so thats not it,
replaced the amp meter, and crimped on some fresh connectors to the wires that bolt to it, THATS NOT IT,
and still when i pop that cable off the engine dies

OKAY so,if the alternators not charging the battery, AND its not running the engine, and the battery is doing all the work, then that must mean that the alternators power flow is screwed up somewhere right? if it ran the engine and didnt charge the battery then i would suspect the VR but thats not the case here.

so that big thick black cable on the back, the one that bolts to the alt, could the problem be there? because after extensively searching the net i found a wiring diagram, and according to the diagram there is a fusible link somewhere in that cable, anyone know where in the harness it would be, lol the diagram shows it being rather close to the alt, but the diagrams probably just showing its conected in series with the wire.(im a novice when it comes to wiring guys so bear with me)remeber i already eliminated the fusible links behind the booster (dont tell me one of those was it) also i noticed that the blue and green wires that go from the alternator to the voltage regulator, run into the coil, should i suspect that, it would seem odd but hey the only stupid question is the one you dont ask....
my dads also been throwing the idea around that it could be the battery cables themselves but i just dont see how that could be, the van starts and runs just fine, but when the battery gets tired well you know

i think ive found something a little more frustrating than body work lol

 

Is the belt on right?

 

"Is the belt on right?"

That would be hilarious.

There are 2 fat wires coming off the alternator. One goes to ground, even though the case of the alternator is grounded. The other wire goes to the battery. Somewhere along there is a fusible link, or should be. My fusible link for the alternator is not in the same harness as all the other ones, but is about 12 inches away. There are also a couple of barrell and pin type connectors on this wire, on mine anyway.

I would figure out which is the hot wire off the alternator and run a jumper cable from it to the battery, for testing purposes. Are you putting a digital voltmeter on the battery? Don't rely on the dash amp gauge.

A lot of older mopar guys would remove the ammeters as they were a known fire hazard. A voltmeter can tell you if the alternator is working. Above 12.8 charging, under 12.4, not charging. The alternator current is then not being routed through the firewall, through the ammeter, then back through the firewall and back to the battery.

Also, fully charge the battery before each bout of testing. A new or rebuilt alternator's brushes have not broken into the armature, and a depleted battery can suck so many amps that the brushes can glaze over or can retract from the armature and get stuck.

In fact this could be happening, and each time you remove the alternator to have it tested, the springs push the brushes back, and it tests fine.

I'd also be testing the field wires in all their bent configurations, could have an intermittant break.

 

OK. you need to remove your wipers first. Then the cowl panel. There's a fusible link on the drivers side under there. It's a black wire that's either 10 ga (60amp alt) or 6 ga (100amp alt). This wire connects to your ammeter and then routes back to battery through barrel connector. GL

 

those are the very first things i checked, the belt and the connections. its funny you mention that theres two wires coming off the alternator, cause mine only has one, its bolted to a post on the back the only other two wires coming off the back are the blue and green field wires. and if there is another i dont see where it connects too on the alt
yeah, i put an volt meter to it 12 volts even everytime
heh ill go out and give the alternator a tap today just for the heck of it, seems the only way to get anything workin is to beat it lol
ill check that fuseible link today they hide these things everywhere dont they?!

 

finaly got the van fixed today, it was a dead short, i was straightening out the wiring harness today, and i noticed that an old add-on wire, probably from the hack job that did the wiring before me had fallen out of the under-dash harness, and wash touching the metal portion of the dashboard underneath so i cut it and capped off the end, when i started the van everything came back to life.

thanks for all your help guys it was much appreciated, one question, i want to install an after market radio in the van but it originaly came without a radio, wich is wierd considering is a conversion van, but anyway any suggestions on where to hook up the positive connections to the radio? i dont want something thats hot all the time, i only want it to work when the key is on naturaly, the memory wire im just gonna run to the battery it needs to be hot all the time so that the pre-sets will stay pre-set on the radio