Need wiring diagram for 85 Wag! Trucks dead!!

[JeepFreak]

Anyone have a wiring diagram for a 85 GW? Replaced the alternator last night and let her run till the battery charged up then shut her off and restarted and all was well. Wife went out to start her this morning and nothing. No dash lights, no starter, no nothing. Acted like there wasn't a battery in there at all. Well got out the portable jump box and still nothing so I am pretty sure I have blown a link somewhere. Really odd though that it could blow overnight??? Asked the wife it she had the clock before she tried to start it and she of coarse said "was I supposed to". She said she wasn't looking. DOOHH! I have never went through the wiring on this rig and like alot of our rigs this one has been hacked on by the PO. I'm not going to even start without the wiring diagram though because who knows whats missing(like fuseable links). Like I said battery is fully charged right now but there is no power anywhere. Ive been really lucky on my Wags and haven't ever had to replace a link on any of them so I have no idea where they are on these. Last night everything worked great and the amp gauge was working properly. I can't think of what would have went wrong in 10 hours of just sitting. If anyone has the wiring diagram please oh please send it my way.

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JeepFreak

[bigblack'74]

BEFORE GOING TO ALL THE TROUBLE OF LOOKING FOR FUSIBLE LINKS CHECK TO SEE IF YOU POWER TO THE STARTER BY USING THE TRUSTY TEST LIGHT. I HAVE SEEN BAD ALTERNATORS FRY STATERS, BUT THAT HAS BEEN MOSTLY ON COMPACT DOMESTICS, BUT IT IS A SHOT FIRST..THEN CHECK ALL 4 POST ON THE SOLENIOD WITH THE KEY IN THE ON POSITION. SEE IF THERE IS ANY POWER ON THEM AT ALL. THE STARTER SEEMS IN SOME CASES TO HAVE A WAY CUTTING EVERYTHING IF IT IS BAD.THATS A GOOD START

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JeepFreak:
Anyone have a wiring diagram for a 85 GW? Replaced the alternator last night and let her run till the battery charged up then shut her off and restarted and all was well. Wife went out to start her this morning and nothing. No dash lights, no starter, no nothing. Acted like there wasn't a battery in there at all. <HR></BLOCKQUOTE>

Of course, check all power points with a voltmeter. But if the battery has juice, the problem is with the wiring or switches (yeah, obvious, I know); it's just a matter of determining which ones. Do the dome lights and headlights work? Weak or strong?

If they work (they get constant power), but nothing else does, then I'd suspect the ignition switch and/or wiring. To check this, turn the key to the "run" position and check for continuity with an ohmmeter between a constant and a switched ignition 12V(+) source.

If NOTHING is working, but the battery is reading ~12V, check the ground wire to the block, from the block to the chassis, and from the battery to the chassis.

I used to consider auto electrical systems a black art; that is, until it became obvious that most technicians were as clueless as I was, and that it would cost me a fortune to find someone good to do it right. A $15 multimeter will pay back for itself in the first 20 minutes you use it, however.

So, it looks like it's time to start pulling some connectors and checking for volts and continuity; Good luck!

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[JeepFreak]

Reading about 13 volts at the battery. Reading about the same at the alternator. I have nothing on the inside of the truck. No dome lights no nothing. With ignition switch on nothing at the solenoid. This one has got me stumped. I was wondering if the ignition switch could cause this but the dome lights don't work nor does the back gate. It's as though someone cut the hot to the fuse box. The ground could definetly be an issue but I have a small ground from the battery to the fender which should be plenty to run the dome lights.

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JeepFreak

[Gladi8r]

Did you have the Battery disconnected when you installed the Alt??? Check that all the battery wires are tight in the battery cable ends. Had Wifey's GW at the shop the other week and they installed a new battery. Well when I went to pick it up the thing wouldn't start. No power at all. It was cold and getting dark when I was there so told the guy to do what he could and I would get it the next day. Turns out that one of the small wires from the battery was not properly installed and was just loose enough to not make contact. It was the wire going to the relay I think. Good luck and remember that it cant be anything major, you only replaced the Alt. Probably just a loose wire somewhere. http://www.ifsja.org/ubb/biggrin.gif

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DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille(to be installed)
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto
71 Gladiator Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld2&.src=bc)

78 GW (parts truck)
360 4v Th400
Dana 44 F/R
http://www.j-trucks.freeservers.com/
78 Wagoneer Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld3&.src=bc)

[JeepFreak]

Ok across the top two posts on the solenoid from positive to each post Im reading full voltage. Ok so my wirings good there. From the hot on the alternator to the positive side of the battery reading 12v so wiring is good there. I have some trace voltage to the fuse panel but with the key on it drops to nothing. This really sounds like a classic ground problem to me but I have checked my grounds and cleaned them all??? So whats next you electrical guru's! I can hold my own on electrical but after checking the obvious I am left with nothing.

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JeepFreak

[JeepFreak]

The funny thing is that she started and ran and charged a dead battery back to full charge. Drove it around last night, parked it, restarted it just make sure all was well and then this morning nothing. I might add Bob that my interior lights don't work right now so Im not sure if they have voltage or not. It did poor down rain last night but it was parked then and can't see that making much of a difference. Im fixing to take the harness lose from the mounting block on the firewall to check for voltage there. You just dont go from fully functional to nothing unless something is wrong. Still seems to me that this sounds like a ground problem so I will keep checking.

I did remove the battery before installing the alternator. I am to lazy to get on the ground so I removed it just so I could get to the alternator better. Nothing seemed out of the ordinary. Amp gauge sat on around 30 for probably 30 minutes untill the battery was charged then went back down to zero.
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JeepFreak

[This message has been edited by JeepFreak (edited January 11, 2001).]

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JeepFreak:
Ok across the top two posts on the solenoid from positive to each post Im reading full voltage. Ok so my wirings good there. From the hot on the alternator to the positive side of the battery reading 12v so wiring is good there. I have some trace voltage to the fuse panel but with the key on it drops to nothing. This really sounds like a classic ground problem to me but I have checked my grounds and cleaned them all??? So whats next you electrical guru's! I can hold my own on electrical but after checking the obvious I am left with nothing.
<HR></BLOCKQUOTE>

To rule out grounds, check continuity between the (+) post on the back of the alternator and the (+) connections inside the cab (fusebox is a good spot to check both constant and ignition-switched (+) feeds). Everything is powered off the 10ga red wire that goes from the alternator through the bulkhead connector at the firewall to the "big-splice" in the dashboard harness. If that wire is fried, you won't any power except what backfeeds through the ammeter.

The usual source for toasting this red wire is a fried ammeter. Does your Ammeter happen to be stuck in one position? If it begins to melt, the plastic housing deforms and jams the needle against the face.

I would focus on that 10ga red wire; check for continuity back to the fusebox, and if there is any significant resistance, check along at different points (bulkhead connector, mid-way along, etc) to see where continuity is restored. If you're lucky, the damage will be obvious (i.e. the wire touched the exhaust manifold).

If the ammeter is fried, bypass it by putting the red and yellow wire ends on the same stud on the back of the ammeter so no current is passing through it. I still recommend a charging bypass wire so that the battery is not being charged from the alternator that is feeding 12V(+) to all other circuits. If your battery is really low and drain is high elsewhere, you can easily toast that 10ga wire if it has corroded or weakened at any point in the last 15 years. I run a 10ga (w/14ga fusible link) back to the 12V(+) feed on starter relay just for charging, so the 10ga wire to the cab only has the job of powering everything else.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[gbarrett]

I had done some work to my 84 GW a while back and somehow the leads on the back of the ammeter had become loose. The power comes from the alternator to the ammeter then to the fuse panel. If you have trace voltage to the fuse panel, check backwards from there - there aren't too many places it could fail between the two.

Hope it helps,

Greg

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84 GW
Driveline is
Stock 360/727 combo.
New paint, carpet, stereo. Rhino grille, etc.

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JeepFreak:
The funny thing is that she started and ran and charged a dead battery back to full charge. Drove it around last night, parked it, restarted it just make sure all was well and then this morning nothing.
[snip]
You just dont go from fully functional to nothing unless something is wrong. Still seems to me that this sounds like a ground problem so I will keep checking.
<HR></BLOCKQUOTE>

YIKES! http://www.ifsja.org/ubb/eek.gif

You let the *truck* charge the dead battery! BIG no-no with the stock charging circuit. Tell me you didn't have the headlights on when you were doing this.

I'd place good money now on a fried wire off the back of the alternator to the ammeter. If you're lucky, your yellow wire survived. Heck, if the dash didn't catch fire when the red wire's insulation melted, then you ARE leading a charmed life.

Even with a separate 10ga charging circuit, though, DO NOT USE YOUR FSJ AS A BATTERY CHARGER. And install a fusible link off the back of that alternator, both on the new feed wire and the additional charging wire.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[JeepFreak]

Bob the battery was really dead. The amp gauge sat on 30 for a long time but when the eye on the battery went green the gauge went closer to zero so I assumed all was well. The gauge doesn't look bad from the front but the back side would tell the tale.

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JeepFreak

[JeepFreak]

Ok checked from the alternator the red to yellow and had full voltage there with key on and off. Im thinking that this is a problem. With the key off I shouldn't have voltage to the yellow wire right??? The PO has the yellow wire wired to the positive post on the solenoid and the terminal B or red wire from the plug that goes to the alternator is wired in to the yellow as well. I am wondering if when I shut her off that the wires were hot and just melted to eachother. I looked at the fuse box and don't see anything there nor do I smell any burnt wires. I guess all I have left to do is to take off the dash I guess. What a pain. Bob the battery wasn't completly dead but it was dead enough that all it would do was click when you tried to start it. There are no fuseable links that I can see at the alternator and I like your idea of running the charging circuit seperate from the power.

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JeepFreak



[This message has been edited by JeepFreak (edited January 11, 2001).]

[JeepFreak]

Quick update! Bob you called it. It was indeed the amp meter. Shorted the two wires and had power again. Lucky for me I have another console with an amp meter so I will swap it out. Question? You talked about putting the charging circuit on it's own leg. Explain the best way to do this so I don't have this problem again and does anyone know what size fuseable link to run off the alternator. Also Bob do I need a link for the charging circuit and power circuit? You guys are great!

Also is it common for the amp gauges to go out or do I need to be looking for another problem as well? The one I took out is still showing continuity however only about half as good as the new one. The old one has gotten hot and started to melt. I wonder if this was because I was trying to charge a really dead battery? Where is the fuseable link supposed to be anyway? I really don't want to fry another amp meter or worse fry my wiring. My wiring shows no signs of getting hot so hopefully it was just the gauge.


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JeepFreak



[This message has been edited by JeepFreak (edited January 11, 2001).]

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JeepFreak:
Quick update! Bob you called it. It was indeed the amp meter. Shorted the two wires and had power again. Lucky for me I have another console with an amp meter so I will swap it out. Question? You talked about putting the charging circuit on it's own leg. Explain the best way to do this so I don't have this problem again and does anyone know what size fuseable link to run off the alternator. Also Bob do I need a link for the charging circuit and power circuit? You guys are great!<HR></BLOCKQUOTE>

After frying, not only my ammeter, but the wiring to it as well (you got off lucky, this time... http://www.ifsja.org/ubb/wink.gif ), I added the bypass charging circuit. All it consists of is a length of 14ga fusible link wire with a ring terminal (you can buy these pre-assembled; I soldered my own connector onto a length of fusible link wire) connected to the back of the alternator, connected to a 10ga wire running to a ring terminal connected to the constant 12V post on the starter relay (the post that the cable from the battery runs directly to). Two or three dabs with a soldering iron and it's done. Of course, your ammeter doesn't indicate the charging of the battery any more, but that's not a bad tradeoff, IMHO.

<BLOCKQUOTE>quote:</font><HR>Also is it common for the amp gauges to go out or do I need to be looking for another problem as well? The one I took out is still showing continuity however only about half as good as the new one. The old one has gotten hot and started to melt. I wonder if this was because I was trying to charge a really dead battery? Where is the fuseable link supposed to be anyway? I really don't want to fry another amp meter or worse fry my wiring. My wiring shows no signs of getting hot so hopefully it was just the gauge.<HR></BLOCKQUOTE>

The fusible link is supposed to be in that red wire off the ammeter; mine was missing anything of the sort, helping to explain why my wiring harness melted.

As far as the frequency of ammeters melting, well, mine did, and others have had theirs melt as well.

Theoretically, the stock wiring and gauges should be able to handle whatever load the alternator might put out, but in actual practice, ammeters melt and wires burn. Hence my suggestion for the additional circuit to bypass the ammeter.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally I wrote:
Theoretically, the stock wiring and gauges should be able to handle whatever load the alternator might put out, but in actual practice, ammeters melt and wires burn. Hence my suggestion for the additional circuit to bypass the ammeter.<HR></BLOCKQUOTE>

Then, I saw your reply to another question:

<BLOCKQUOTE>quote:</font><HR>The newer wags had a 61 amp but there was an option for a 84 amp one. It is about double the price at the part stores but it is what I run on my wifes 85 Wag. I'm worse than Tim Allen when it comes to the bigger is better question! Funny thing though, when I installed the larger one the back window rolled up and down with no trouble. Before I thought it was going to die.<HR></BLOCKQUOTE>

That ammeter is only rated for up to 60A; guess what melts when you put more than 60A through it...? http://www.ifsja.org/ubb/frown.gif

DEFINITELY add the ammeter bypass if you're running a high-output alternator!

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[JeepFreak]

Bob whats the easiest way to see if the regulator is working in the alternator? Filled the battery with water and she is bubbling some out(very little). I normally world not worry about this but given the state of my problem I don't want to fry a battery also. I took a reading and the battery with the engine off is at 12.5 volts and running is at 14 volts. Battery is not fully charged yet so I am thinking of going and getting an auto charger tomorrow and leaving it on the battery overnight.

Also I took the 84 amp back to my buddy's part store and got the 61 amp one. I need to upgrade some wiring before I go getting power hungry!


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JeepFreak



[This message has been edited by JeepFreak (edited January 11, 2001).]

[BobBarry]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JeepFreak:
Bob whats the easiest way to see if the regulator is working in the alternator? Filled the battery with water and she is bubbling some out(very little). I normally world not worry about this but given the state of my problem I don't want to fry a battery also. I took a reading and the battery with the engine off is at 12.5 volts and running is at 14 volts. [snip] <HR></BLOCKQUOTE>

You test it by checking the battery voltage when the engine is running; if it's in the acceptable range (~13.8-14.4V@1200rpm or so), then the regulator is working fine. A voltmeter would show if it is intermittently spiking or dropping.

As for high-output alternators, they are usually not a must-have; anyone recall an editorial in one of the off-road mags where a guy with a flatfender had a bad high-output alternator, so "temporarily" replaced it with a 40A unit he had lying around? He's apparently still running it, as it was sufficient for the amount of winching and off-road lighting he needed it for.

Since high-output units are generally less-efficient at low-rpms, this may be one of those places that just enough is better than too much.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/