I've searched around for the answers, but came up empty. So I'll just come out and ask...

1.] Do cherokee 1998 alternators abruptly and irreversibly die? Or can they intermittantly and slowly die?

2.] The 4 wire harness on the back of the alternator, does it have a ground wire in it?

3.] Can a bad/dirty starter connection cause intermittant charging issues?

I went up north with my friends this weekend, and my alt gauge dropped to 11-12ish. It would intermittantly go back up to the 14 {normal} usually after a re-start, and occasionally drop to nothing with the check gauges light on. Rarely will the power output increase without restarting it. Also, it likes to work better when warm.

I assume there must be wires and contacts to clean that might help. I've cleaned the usual grounds. I also took off the alternator 4-wire connection and cleaned it. Problem is, I dilithium greased it and was wondering if that's good or bad. The issue was present both before and after the cleaning.

Which wire from the alt does the electricity it makes go through, and to where?

Thanks for your help!

 

From my knowledge and experience yes an alt can come and go. Cause by the internals

Yes a bad connection can cause an issue and create an open circut so the battery won't charge.

It will most likely be an alt issue tho

 

The gauge you have is your battery voltage gauge not the alt gauge. This gauge is notoriously unreliable and should not be trusted when verifying/troubleshooting issues with the charging system. You can take the alternator out and have it load tested.

do you have a multimeter? If so, you can have a quick glance at what your alternator is doing, by measuring battery voltage with engine off. Then start the car and measure again, you're looking for an increase of voltage of > 0.5V. Then, with egine running, start turning on the accessories like lights, radiao, AC, fan on high etc and see if the alternator can keep up with the increased demand. This gives you a rough idea how your charging system is going.
If the volts are not high enough, it does not immediately mean your alt took a crap. Things like cables, connections etc can be in play, as well as low belt tension etc. Many other things.
Remember: the alternator charges the battery.

So, go and do some on-board testing and let us know!
(or, if you cant be bothered, take both batt and alt out and have them tested in store

pm: ericthecarguy.com has a few nice videos on testing your charging system. All explained, in a nutshell.

 

Which connections should I check? The battery cable heads have been cleaned and changed. The back of the alternator was cleaned and di-lith greased. Any other conns?
What about the starter wires?

 

The Star Trek crystaline stuff?
If you mean dielectric clean it off with brake cleaner, electrical connections are best clean & dry.

 

You more than likely have a bad alternator. One or more of the diodes inside are bad. Alternators do wear out.

You don't have to take out the battery or alternator to have them checked. Auto parts stores can do a load test right there in the parking lot.

Bring money to buy a new alternator, assuming you are going to install it yourself. If not, bring money to your favorite mechanic's shop and get someone to follow you to pick you up while they work on it.

Do this soon before you are stranded.

 

Did you mean you used Dielectric grease?

Dielectric grease prevents corrosion when applied directly to metal connectors, but it can sometimes cause a connection to stop working if not all of the grease is pushed out of the way between the points of contact inside the connector. Just an FYI.

 

Yes, dielectric, sorry. Just a smidge. Some on my fingers with a light app. I live in michigan and everything rusts. What other grease should I put on it? Literally, I cleaned the contacts on he 4point harness last month, they're rusty already. Hence the slight greasing. Any suggestions?

 

Also, just took the alternator off. Only took a minute. Went thru the top, took out the battery shelf. What's the sensor in the shelf bottom do?

Btw, the wire to the top of the alt, from the fuse box looked horrible! I cut off 2 inches, and reconnected the round mount end. Post cleaning the heck out of it. Might've been the sole problem, but I'll run the alt over to the AZ for a check anyway.

So, alts CAN go out intermittantly? I thought when they're fried they're fried.
Info?

 

1998 5.2l durango alternator. 136a, has the same connections as the newer XJ's, and fits the mounting bracket with some grinding.

 

"So, alts CAN go out intermittantly?"

That's what mine did.

Code said either bad wiring, computer/ECM or alternator field.

Replaced alternator, problem never reocurred.

 

It is a battery temp sensor. It helps the computer regulate the charging system.

 

Often times they go out intermittently... Some do it as they warm up (usually an open in the coil windings)... Some do it with humidity changes (wire insulation break down)... Some do it because of worn brushes... In any case remove the alternator and open it up... There are several tutorials (even videos) online to instruct the proper testing process (VOM needed)... I rarely buy a new alternator... Most often it can be fixed (brushes, diode trio, or internal regulator) for less than $20... Do make a scratch mark down the length of the cases prior to removing the bolts... This insures you realign the cases correctly on reassembly...

 

Update...
Took it to the AZ. They ran it. It passed...

I was surprised. Asked to have it run again... it failed 1 of 3 steps.

Asked to run it again, failed 2 of 3. On the 3rd run, failed all 3.

LESSON: ask to run it multiple times. It simulates a warm engine. Got a new one. Works fine.

Also, sidenote, got the 40$ Piolt brand rectangle fog lights. Very nice, easy hookup, multicolored if desired. Very bright. Plus, the wiring harness was easssssy and nice.

Thanks for the help!

 

Great! glad you got it going.
As a side note dielectric grease works great for spark plug boots (that's the original use). It makes removal easier, and should help prevent arcing past the insulator.