1998 Jeep - Swapped Alternator's and the new one is frying my 20A fuse

[Candymancan]

I know my vehicle isnt a sports car or whatever you guys have on these forums.. But i found a link to this website while doing google searchs on my problem.. The people on jeepforum.com havent a clue so i was hoping you guys could help me.

I have a 1998 Jeep grand cherokee 5.9 liter v8.. It came with a 150A alternator from factory.. The 5.9 Jeep was a very limited number production and because of this they dont have an aftermarket for its one of a kind parts which include this alternator.. I have to downgrade to a 136 for a direct swap... Which sucks.. and all the other 5.9 owners have the same issue.

So there are a few how to threads on how to get around this.. They call for taking the durango/dakota/ alternator from a 5.9 engine which are 160Amps and swapping it to our vehicles.. The only problem is these trucks are from 2001-2005 and in 99+ they changed the pigtail plugs on the alternators to a new standard. But the writeups show how to swap your old pigtail to the new one.. and its pretty simple..

I got 3 pigtails from a JY.. I cut off my old one and proceeded to follow the guide.. The guide called for cutting the ring connector off on the pos and negative cables as well because you need a larger ring connector for the positive bolt on the back of the alternator.. I did that and crimped the connector to the POS wire and also soldered it and taped it.. The negative i did the same thing.. Now the difference between the old alternator and the new one is the old one had a direct ground going to it.. The new alternator doesnt but all the guides say you can just plug the ground to a bolt behind the alternator where there are already a few grounds.. Which i did..

The other 2 wires go to the PCM which is where the voltage regular is "external regular" and something else. The guides claim the order these wires plug up doesnt matter.. The new pigtail had a solid green and a brown/orange wire. Mine were solid green and green.purple.. So i wired both solid greens together and the green.purple to the brown/orange..

I hook it all up and when i turned the key to the on position i had no gauges no power and no gas.. It wouldnt start either just crank.. I checked the fuses and i blew a 20A fuse in the box inside the engine bay which controls the Alternator/PCM/O2 sensor and fuel pump.

I tried a new fuse and same thing blew as soon as the key went to power.. I unplugged the pigtail on the alternator and tried a new fuse and it works and my gauges work, shows battery and fuel level... So the alternator is blowing that 20A fuse when the key is flipped in the on position.. Why is that ?? Did i wire these wires incorrectly ?? I dont see how the alternator could be bad.. Its brand new remanufactured. I dunno, i need my car its been sitting for over a week and ive been carpooling and sharing a car with friends.. I do landscaping so this is my lively hood.. I need this working. The only other thing i can think of is the old alternator ground pluged directly to the alternator.. This one doesnt have that.. But isnt the alternator case itself and the engine it bolts to a ground ? So i dont see why that would matter.. Maybe i should take the ground and bolt it to one of the case mounting bolts ? I dunno

Please help sorry for a long post but i wanted to give as much info as i could.

Here are pics on how its wired. And the link to the writeup.. as you can see its wired correctly i believe ? Maybe i should swap the green wires on the pigtail ? The solid green to the brown/orange and so forth ? I dunno...http://www.jeepforum.com/forum/f13/write-up-durango-160amp-alternator-swap-1330999/

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[Candymancan]

okay update.. I rewired the pigtail swapping wires.. and this time doing that the 20A fuse didnt blow when i turn the key to the power position.. Gauges worked for battery and fuel.. so i turned the key and it started.. Voltage on the gauge was right in the center of 14v. So i got out and was checking the engine bay out when suddenly the lights got super bright and i went back to the car and the battery gauge was reading 0v but the Jeep was running and the lights were bright as hell..
Sigh what now ??? The 20A fuse isnt blown this time..
Turned it off and turn it back on and same thing, and i turned on the headlights and dash went crazy speedomter and rpm gauge were up and down and so were the other gauges... So i turned it off and unplugged the alternator and turned the Jeep on with just the battery and it ran fine despite the low voltage because it was on battery power.
What the hell is going on ?

 

[Maes]

It sounds like your voltage regulator in the alternator blew and its dumping way more voltage to your charging system which is bad.

 

[Candymancan]

well the voltage regulator is in the PCM and if thats the case im f***ed... I love my Jeep and love the engine... but man im hating old cars.. Ive spent so much money n time fixing both my 98 grand cherokee's.. and a PCM for a 5.9 is going to be hard to find...


UHG i dunno what to do... Should I pick up a regular lower amp alternator from the auto part store and hook it normally and see if the regulator really is bad.. Or maybe its just the wiring on this durango 160 wont work, i dunno im at the point where you know everything breaks, nothing good happens and you just want to give up...

 

[Maes]

The alternator should have a regulator inside of it. Not in the pcm

 

[Candymancan]

No its in the PCM on most chrysler vehicles of this era trust me i know this for a 100% fact


This is a external regular kit for this reason in case your regulator goes bad you dont have to spend $200 on a new PCM... But im really hoping it isnt the regulator... Tomorrow im just going to downgrade to a 136A alternator and hook it up like normal and see if it charges right.. Perhaps doing this cut and splicing wires and plugs just isnt sending a good signal to the regulator.. The Jeep is charging like the wires to the regulator arent hooked up.. or as if the regulator as you said is bad.

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[Maes]

Well good luck man

 

[Maes]

I was just stating the obvious

 

[Candymancan]

okay im sorry ?

Now what do you think is wrong.. The guides claim the wiring of the green wires doesnt matter which way they go yet one way pops fuses the other way acts as if the voltage regulator is dead.. which i hope isnt the case.. The only way i can check that is get a normal Jeep alternator and hook it up normally to check and see if the regulator is regulating

 

[crimsondragon]

Did you get a voltage reading off the alternator and see what it was putting out?

 

[1990TSIAWDTALON]

Could you not buy the rebuild parts for your alternator, is that what part of the problem is? A new regulator, diode trio and brushes are the normal rebuild parts. Just trying to help.

 

[darknezz7]

Have you used a multi meter to confirm your grounds and wiring?

Yes the alternator case ground to the engine BUT, I have seen them put the main ground FOR THE ENGINE at the alternator. So make sure you still have a good ground from engine to body or just put another one on.

My cherokee has a ground from batt straight to body then straight to engine, then straight to body again, had ground issues before not now.


You say you want a newer car? Trust me, unless your talking dealer warranty new (still look to the car being in shop half the time) youll be working on any newer car just as much or more.

The cars I have had the least trouble with is my 89 cherokee (260k orig miles) and 85 bmw (over 300k miles). 90's and early 2000's cars are constantly breaking and new cars are only made to last 100k miles before they completely fall apart. I have owned several dozen cars from 80's 90's early 2000's and work on everything from fords, kia, vw, toyota ect.

Of all the new cars, Toyota is STILL the most reliable and best engineered.

 

[Candymancan]

I called an alternator shop they also said those 2 green wires doesnt matter which way they are plugged. Well my regulator is fine.. I said F it and i got a 136A from autozone. Hooked it up with the regular pigtail and Jeep works, runs and drives and charges fine.. Electric fan comes on and the needle doesnt even dip. So my voltage regulator is good thank god.



Shoulda just got a 136A in the first place, its a downgrade from the 150A but woulda saved me alot of hassle with that 160 swap. That was the whole point in doing this 160A durango swap.. because my 5.9 has an electric fan vs a clutch fan so it draws alot of amps. Thats why they put a bigger 150A in there.. But they dont make 150A alternator due to this being a limited production Jeep (only like 10k made) I did go to a few shops who would rebuild my 150A but they wanted $200 which is freaking insaine


So i have no idea though why the 160A wont work it makes no sense to me.. why the Jeep wont regulate it. It charges the system like there is no regulator hooked up.

As for the ground, yes the alternator is and should be grounded.. On the ZJ grand cherokee's the alternator have a direct ground from the battery to the back of the alternator. I grounded the 160A im trying to get to work the same way, just took the ground ring terminator and put it directly on the alternator case by one of the mounting bolts. So i have no idea why this 160A alternator wont work..

It charges but the voltages was at 17v for some reason its like the regulator isnt hooked up to it. Like some of you thought i thought i fried my voltage regulator in the PCM but getting this normal 136A Jeep alternator proves the regulator is fine. So why wont this 160A work ?

Yes the pigtail on it is different but the 2 wires going to it are the same all they changed was the plugs . Any ideas why the regulator wont regulate this 160A alternator ?

 

[Candymancan]

well i had the alternator checked by a independant alternator shop they said its fine and putting out the correct amps and voltage.. They also said the way im wiring the alternator is correct and they are just as stumped as me as to why its poping fuses or overcharging like there is no regulator

 

[Dsmkauai]

To me it's where you had the ground connected. It's not really attached to the alternator casing and needs to be. It's hard to tell from your pic but normally it's grounded right to the back of the alternator. Not on a bracket off to the side. That ground is really important with that much juice flowing. Should be on a case mounting bolt like you suggested In your first post can you post a picture of the back of the 160amp alternator? Id like to see if there is any spot that looks like a grounding point.

 

[darknezz7]

Yeah sounds like ground issue to me too.

Good that its working though, I doubt you will notice much difference. I think mines only like a 90amp , I too want to upgrade but to the v8 GC 136.

 

[Candymancan]

eI notice the diff from the 136 to my old 150 when my electric fan kicks on the battery boltage is slightly lower then with the 150 it dips near the first line to the left. I didnt do this to upgrade really i did this because there are no 150A alternator replacements for my Jeep.. All the shops list the replacement as the 136A and i just didnt want to downgrade.

But for now i at least have my car running, i have to figure this 160A issue out soon because i wont be able to return it to get my money back if i wait too long.

Anyway here is what the alternator looks like lemme know if this link does or doesnt bring you to the alternator.

http://shop.advanceautoparts.com/p/...rans&utm_campaign=shipped&utm_content=general





there really are no ground points in the back of the alternator. So i re-mounted the ground wire to the lower mounting bolt against the case in the front and it still pops fuses and or charges super high. Shouldnt that have properly grounded it ?

What had the guy in the alternator shop confused was the 2 smaller wires which go to the generator field source and generator field driver.. Can be mixed and matched doesnt matter which way the wires are splice together.. Which was proved by me putting that 136A on as i lost the original pigtail and guessed which way they were wired. So if 2 alternator shops and 2 guides say it doesnt matter which way those 2 green wires are connected to the plug then he was confused to as why one way would pop a fuse and when i reverse the wires the other way it would start but charge really high.


I wonder would the pigtail harness be bad ? Probly not, tomorrow i was going to try a 2nd pigtail i got from the jy to make sure.. Where else do you think i should try to mount the ground on the alternator ? If directly on the case in the front mounting bolt didnt work then where else note the wire is only so long too

 

[Dsmkauai]

One of those three bolts on the back is the dedicated ground for the alternator. It's to hard to tell by that pic which one. But like I was saying they all have a dedicated power and ground. Let me see if I can find some answer for you and see if we can't figure out which on it is. Can you look at yours and see if anyone has a little - sign by it? Or take a pic of the back of yours and post so I can see better. Zooming on that pic you gave makes it blurry. I'm reading you have to add a external voltage regualtor for it to work. Let me read some more to confirm k. Makes sense since you said it was putting out 17v. I've done this before for almost the same issue. Oh ya it was on a jeep I remember now

 

[Candymancan]

Those 3 bolts are just for the cover i thought ? Im not sure how id get the ground wire on those tiny screws the ground is pretty big. I mean i could try but i think those are just the screws to the take the back off. My old alternator has those as well and the ground wasnt on them it was bolted to the outer casing

My jeep does have an external regulator its in the PCM thats what those 2 green wires go to. Here is a picture of how its wired.. I tried it again.. Cut the wires went clean, use connectors this time vs soldering and i used a different pigtail.. I mounted the ground on the bottom mounting bolt in the back this time. Turned the key to power and click poped the stupid fuse again... grr Here also is a pic of the power distribution box under the hood the fuse that keeps poping is the smaller 20A fuse. Under that upper 15A fuse there is an empty spot thats where the yellow 20A goes and always pops. The alternator guy suggested i put in a larger fuse... but yea i dont think i wanna risk frying my PCM im pretty sure that fuse is there to protect it

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[Dsmkauai]

I know but your PCM regulater isn't working and ya your right the ground just goes to the case, I see now. Ive done the external regualtor on a jeep before with your same issue and it worked. I remember now, but that issue was the PCM reg was messed up and pushing out 17v. I found a right up on it and that's what the fix was adding a external to bypass the pcm's. Reading some more for ya. You may need a 30amp fuse to combat the higher output of the alternator.
https://snapguide.com/guides/fix-jeep-grand-cherokee-alternator-not-charging/

 

[Candymancan]

Well how can my regulator be messed up if it regulates the stock Jeep 136 and 150A just fine ? Remember i put in a 136A alternator with the original ring connector plug for those 2 green wires.. and it worked fine today.

Here is what the original alternator pigtail looks like.

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See the 4 ring terminals on that black box ? The 2 larger ones on the side were ground and bolted up to 2 points on the outer casing. The 2 smaller ring connectors on the bottom of the box bolted to the back of the alternator. The new alternator has that brown plug you see in the picture. Which elimiated bolting it to the alternator. All you had to do was clip it in. So what the guide calls for is cutting the ground and 2 green wires off that ring connector pig tail.. Then putting a ring connector on the ground wire and wiring those 2 green wires to the new pigtail plug.

I did all that yet it keep poping the fuse .. Uhg.. The only difference i can see from the old case to the new one is the old case had 2 grounding points with the big ground wire. The new case doesnt have any grounding points so i have to take the big ground wire and bolt it to the case VIA the mounting bracket.

One thing i do notice on my new alternator the one causing problems is its painted black in the middle. The alternator in the picture above isnt painted. I mean i dont think thats doing it but who knows at this point

 

[Dsmkauai]

Not saying the PCM reg is messed up saying it's not handling the 160amp output. The 139a is not a issue cuz it's lower than the stock. I'm following what your saying bro on the same page Another thing could be the pulley size. Is the 160a the same pulley as the oem you took off? Is it painted where your trying to ground it? That could cause a weak ground if so. And you should scrape the paint off. Either use the 139a. Or if you really want the 160a and not have it throwing out 17v. Add the external reg and problem solved.

 

[Candymancan]

Well pully wouldnt matter at this point because its poping the fuse when the key is on the on position you know for power before you crank.. havent even started the jeep. If i swap wires i can start it though.. But yea the pully is the same, this alternator goes to the same engine 5.9 V8.

That is what i asked the dude at the alternator shop could it be just the regulator doesnt like this 160A alternator. I dont think that is the issue, as people with the Inline 6 4.0 engine have done this 160A swap and there original alternators were only 90 and 117Amps.

Thanks for the help, i know this issue is frustrating.. imagine how i feel.. downgrading alternator from 150 to 136 is not something i want to do... but its looking more and more like i might have too

 

[Dsmkauai]

If it pops the fuse just turning the key it's shorting out for some reason. Or the 20amp fuse is to small for that alt. Just do the 160 and add the ext reg won't hurt anything. Then make sure it's wired correctly so your not blowing fuses. All good bro I'm helping my friend with a nightmare dodge that keeps popping fuses with the key on. Lol. Thank God for short finders haha. Question what falled on the 150amp that you needed to replace it?

 

[darknezz7]

You shouldn't "have to" something is wrong, find it, fix it.

Do the external regulator.


Ah love my Renix, not much for a PCM .