Large case 3G install w/Explorer charge harness

[85crownHPP]

I got some sunshine and only worked a half day yesterday so I went ahead and threw a 3G into the p72.
I used a large-case 3G from a '95 3.8 Taurus (to replace the large-case externally regulated one that commonly comes on the police box's) with a 3G charge harness from an older explorer. Look for the one with twin fuse links in the charge cable.

Fitment was a direct plop-in once again, no cutting or grinding of the bracket needed. I did have to remove the brace between the bracket and the intake manifold, the extra bulk of the 3G was contacting it, limiting its travel. Not all boxes have that brace anyway so it should be fine.
The car already had a XXX507 belt on it, so it fit fine.
Also I noticed while handling a few large case 3G's that they seem to all have threads in the top mount, unlike the small case which require using a larger bolt with a nut. The large cases needed a smaller metric thread bolt.

The wiring couldn't have been any easier...
First I disconnected the battery and removed ALL the old alternator's associated wiring that did not involve any cutting. Most of it should disconnect in several places allowing you to remove it. NONE of the original wiring is needed when installing a 3G except the green/red wire for the warning light. This one is usually easy to find and isolate on the fender too.
I ran the charge cable to the '+' terminal on the battery (doesn't reach the solenoid) and wired the yellow wire to self-sense (hook it to the output stud).
The green wire is tucked away in the loom with the factory engine wires and pops out where you see the blue tape and joins into the warning lamp wire.
Also don't forget to remove the solenoid end of the original charge harness.

Its charging a beautiful 14.6 volts... total cost, $25

[87gtVIC]

Very nice. So the built in fusible link (assuming the black thing those two strands of wire coming out out the one large strand of the Explorer charge cable are the fusible links) would take the same function of a mega fuse, correct?

Was that lower alternator bolt a pain to back out?

[85crownHPP]

Those lower bolts are always a pain... lol...

And yep - those grey ones look like the single link that was on the 85's old 65amp ex-reg alternator... 2 x 65 = 130 so I figure Im good
Those Explorers either got a 95 or 130 amp 3G (doesn't fit in boxes) and i saw some with one fuse link and some with two.
OE FTMFW!!!

[87gtVIC]

Sure is cleaner looking than having a mega fuse in the entire flow of the wire.

[Archangel]

Right, but when the links blow for whatever reason you're pretty much fucked, whereas with a megafuse you can replace it and be on your merry way (assuming the issue is intermittent and not some major VR malfunction or something else of the sort).

By the way Pete, the green wire with red tracer ain't really for the light, it's the key-on trigger for the VR. I know what the wiring diagrams show, but it don't really work this way, at least on my truck it don't and the diagram is the same as what's in the Panthers - I actually have the alternator trigger on a manual switch running directly off battery power (this way I can lose the main harness and still keep going, with the CB and some lights working to boot), and my voltmeter gauge and battery light still work fine... go figure, lol. About that top alternator bolt, it's M8, and I drilled mine out for a 3/8" bolt with a locknut on the other side - fuck that small shit in threaded aluminum, I don't trust it for how much I have to tighten down my belt.

[85crownHPP]

Right, but when the links blow for whatever reason you're pretty much fucked, whereas with a megafuse you can replace it and be on your merry way (assuming the issue is intermittent and not some major VR malfunction or something else of the sort).

*when* it blows? lol... I don't think I'm going to pull more than 130 amps...
I bet you could though with all your stuff! You have power inverters and all kinda stuff in there right? And even in case something heinous happens, Ill just keep a spare one in the trunk, since they are cheaper than a replacement fancy fuse I guess you could always even double up the charge wires to be extra covered.

By the way Pete, the green wire with red tracer ain't really for the light, it's the key-on trigger for the VR. I know what the wiring diagrams show, but it don't really work this way

Yeah i figured out it was the trigger to when I did the 85... it didn't charge until i hooked it up. I forgot to mention that in this install thread... Doesn't it serve both functions? trigger/excite and the warning lamp? My EVTM's have been pretty trustworthy so far :p

[Archangel]

*when* it blows? lol...

Yeah, I know, but that asshole Murphy don't sleep either, lol

I don't think I'm going to pull more than 130 amps...
I bet you could though with all your stuff! You have power inverters and all kinda stuff in there right? And even in case something heinous happens, Ill just keep a spare one in the trunk, since they are cheaper than a replacement fancy fuse I guess you could always even double up the charge wires to be extra covered.

Actually I don't think you can't really pull more amps through that harness than the alternator provides, the most you can do is those 130 amps continuous, it will likely damage the alternator due to the 100% duty cycle, but it won't blow the fusible links due to overloading. When I have all my lights and what not running the 130-amp alternator cannot keep up with the demand, and as a result I can watch my battery voltage slowly drop, but that's it, nothing really fries or gets damaged in other ways.

The fusible links will go poof tho if the rectifier shits the bed and the alternator decides to short out internally. Theoretically speaking if your VR spikes up and shoots say a 150-amp charge through the cable the links would burn too, but that's simply cause they can't handle that much current, which is not to say the batteries cannot absorb it - basically the OEMs use the smallest harness that can semi-safely handle the maximum charge the alternator is able of producing and then fuse it according to the wires chosen - they can certainly do like me and run a 1/0 cable fused at 175 amps, but that's a whole lot more expensive than two 10-gauge wires fused at 65 amps. In other words the fusible links are really for protecting the electrical system (the batteries in particular) from grounding due to alternator failure, not so much for protecting it against too high of charge.

Yeah i figured out it was the trigger to when I did the 85... it didn't charge until i hooked it up. I forgot to mention that in this install thread... Doesn't it serve both functions? trigger/excite and the warning lamp? My EVTM's have been pretty trustworthy so far :p

I dunno man, it's supposed to be for the lamp too, but like I said mine works just fine without that wire even plugged into anything. I guess you can always verify it for yourself, disconnect the trigger wire and temporarily install a manual one in its place, then watch your gauge and warning light and see what they do...

[85crownHPP]

You mean your battery light works even without the green wire hooked up? Its on with the engine off and goes out when you start it up? interesting...

[Archangel]

Yeps, does just that

[gadget73]

The amp light in the dash is run off the green wire. It goes from key-on + to the light, and from the light to the alternator. Light is in-series with the circuit, and it doesn't work if you remove the light and the resistor that bridges it. Unplug the cluster sometime and you'll see it not charging. The circuit pulls a very tiny amount of power under normal conditions, so the bulb won't glow. When something happens, it grounds at the alternator and the bulb comes on.

[Archangel]

Well then why does my light come on and goes off like it should upon startup, then if I kill the engine with the ignition still on (I can do that) it comes right back on? The green wire ain't connected to anything no more...

[gadget73]

no idea, but in stock Panther configuration, the light is in series between key switched hot and the I terminal of the regulator. I haven't got a clue what may be going on with diesel wiring or your specific diesel wiring

The other thing with pulling the cluster I found out because 86Vicky did it, and the alternator quit charging until he plugged it back in. I also had the same crap years ago on my VW. It wouldn't charge with all new working parts. My uncle asked me if the bulb worked. Sure enough, the damn thing was burned out. New bulb and everything was good.

[91waggin]

Well then why does my light come on and goes off like it should upon startup, then if I kill the engine with the ignition still on (I can do that) it comes right back on? The green wire ain't connected to anything no more...

Maybe it goes back into bulb-check mode because the engine is off?

On the other side of the coin, the bulb check mode might simply be activated because the alternator isn't charging (because the engine is off)

[GM_Guy]

The light is supposed to come on if the engine dies. When the alternator stops turning, it has no output and the light comes on.

Alex.