97 TJ alternator swap question

[romankastle]

Hey there, I'm new here and this is my first thread post.
I turned 19 recently and my parents got me a 97 TJ for my first vehicle. Its a standard Sahara, green with a tan hard top. I love it dearly, but lately its been having some minor issues that I have been able to fix for myself. Now though I'm up for a bit of a challenge, my alternator doesn't seem to want to charge my battery anymore. Its brand new battery from Oreille's, only two weeks old. When turned off its about 12.2v when running I'm at 11.75-9v(checked it with a multimeter). So its not charging at all. I've checked and cleaned almost every connection I could find, and that hasn't solved it so I'm pretty sure the alternator is done for. I'm about to install a wench and sound system so I'm gonna need bigger ALT anyways I'm thinking 160 amp. I'm just not sure if one that size will fit. I've read that you could do a swap with a salvaged ALT from Durango, but I was wanting to install a new one. From what I've read a new 160amp wont "fit", but no one explains why. I was wondering is you guys could help me with some advice and answers. I've done a lot of my shopping through extreme terrain if that helps. Thanks in advance!

 

[Jerry Bransford]

No need for a bigger alternator because you're installing a winch, the winch draws most of its power directly from the battery. No way can any automotive size alternator keep up with a winch that can easily draw >400 amperes. I have actually had to use my winch a couple times when I couldn't start the engine, the battery is the key to good winch performance.

Also, while the alternator MIGHT be bad, it regulator is actually contained within the engine computer (PCM). So the problem could be in the alternator, its voltage regulator inside the PCM (mounted on the firewall), or the cables or their connectors. Give the cables and where they are connected to their connectors a very thorough examination.

By the way, I have done a lot of winching the past nearly 25 years and have always had the stock factory alternator with a very good heavy-duty battery.

And a big welcome to WTF!

 

[qslim]

Hey there, I'm new here and this is my first thread post.
I turned 19 recently and my parents got me a 97 TJ for my first vehicle. Its a standard Sahara, green with a tan hard top. I love it dearly, but lately its been having some minor issues that I have been able to fix for myself. Now though I'm up for a bit of a challenge, my alternator doesn't seem to want to charge my battery anymore. Its brand new battery from Oreille's, only two weeks old. When turned off its about 12.2v when running I'm at 11.75-9v(checked it with a multimeter). So its not charging at all. I've checked and cleaned almost every connection I could find, and that hasn't solved it so I'm pretty sure the alternator is done for. I'm about to install a wench and sound system so I'm gonna need bigger ALT anyways I'm thinking 160 amp. I'm just not sure if one that size will fit. I've read that you could do a swap with a salvaged ALT from Durango, but I was wanting to install a new one. From what I've read a new 160amp wont "fit", but no one explains why. I was wondering is you guys could help me with some advice and answers. I've done a lot of my shopping through extreme terrain if that helps. Thanks in advance!

First off good on you for tackling the TJ. When my nephew was 19 he had no inclination to even get a DL . He's 26 now & just recently started driving because my sister threatened to kick him out of her house if he didn't start working.

You'll find absolutely everything you need here to get any problem fixed yourself.

Jerry's right about the regulator & winch, but from what I've read on here (I have a 99) the earlier PCMs are fairly solid compared to later models, but you never know what can fail being 22 years old. If you're certain the connections are good, battery cables etc. are good, I'd throw another alternator at it.

BTW you can grab your factory manual for free over in the Resources sub-forum (the '97 manual is all the way at the bottom for some reason). There's a procedure in there to do a voltage-drop test on the charging system to make sure that there isn't excessive resistance soaking up voltage i.e. corroded cables, poor connections etc.

Also do everyone a favor & finish filling out your profile with the particulars of your TJ. It makes it easier for everyone to help you when they can see what you have.

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/

 

[SSTJ]

Welcome to the Forum!

It's true about the stock alternator being sufficient. Jerry answered similar questions of mine here.

Also, you have a 97! Welcome to the club. There are a few 'quirks' with the 97s, and you might enjoy this thread. If you discover any more as you go, let me know and I'll keep the list up to date.

 

[romankastle]

First off good on you for tackling the TJ. When my nephew was 19 he had no inclination to even get a DL . He's 26 now & just recently started driving because my sister threatened to kick him out of her house if he didn't start working.

You'll find absolutely everything you need here to get any problem fixed yourself.

Jerry's right about the regulator & winch, but from what I've read on here (I have a 99) the earlier PCMs are fairly solid compared to later models, but you never know what can fail being 22 years old. If you're certain the connections are good, battery cables etc. are good, I'd throw another alternator at it.

BTW you can grab your factory manual for free over in the Resources sub-forum (the '97 manual is all the way at the bottom for some reason). There's a procedure in there to do a voltage-drop test on the charging system to make sure that there isn't excessive resistance soaking up voltage i.e. corroded cables, poor connections etc.

Also do everyone a favor & finish filling out your profile with the particulars of your TJ. It makes it easier for everyone to help you when they can see what you have.

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/

Awesome thank so much for your help! I’ll defiantly keep that in mind about the manual. Definitely gonna need that haha. I actually did a resistance test earlier, negative to battery and positive to ALT housing. I got a reading of -0.18v, so there is defiantly some resistance. Now I know that’s not good, but what it means I don’t know. Most of the articles I’ve read like before didn’t really say. More of a “get a new ALT response”.

 

[TJ4Jim]

Awesome thank so much for your help! I’ll defiantly keep that in mind about the manual. Definitely gonna need that haha. I actually did a resistance test earlier, negative to battery and positive to ALT housing. I got a reading of -0.18v, so there is defiantly some resistance. Now I know that’s not good, but what it means I don’t know. Most of the articles I’ve read like before didn’t really say. More of a “get a new ALT response”.

Since your diving into the Jeep world and getting into wrenching on your TJ there is a lesson many have learned the expensive way. Stay away from box store parts like your new alt and especially any of the sensors or electricals that almost always need to be Mopar or NTK (no Bosch oxygen sensors) as they are either dead out of the box or do not play with the TJ computer system. Water pump and radiator quality is also rock bottom.

Also spend some time in the resource section where there are numerous "how to's" and Factory Manuals available.

 

[JKP]

As for your alternator, you can remove and take it to most any parts store and they will test it for free.

Just don't buy one of the cheap store brand alternators or you will become very proficient in changing it...