I have a 98 xj an have been having a voltage problem. When I start it my volt meter comes up to 12 volts than will sit there for a few minutes than drop to nothing but sometimes it will climb to 14 volts. I cleaned all the alternator connections and it didn't help but if I start it than jiggle the black box(regulator?) in the alternator I can hear a slight high pitched sound and my voltage climbs to 14 volts. Needless to say I'm getting tired of getting under it every time I start the damn thing. Anyone had a problem like this or have some direction for a shade tree mechanic like myself? The black box looks to be part of the wire harness and I haven't been able to find one at my local parts store.

 

I also have been having a false low wiper fluid light that comes and goes and my radio will cut out when the windshield wipers come on which also comes and goes. I also have a turn signal problem that moves around. First the back signals would blink at the same time than that went away but the front driver signal quit working but would work When the hazards were on. Once again this problem comes and goes. Not sure if it is relevant or not but figured I should mention. Maybe something in the steering Column?

 

Pretty sure the regulator is in the PCM in '98, not part of the alternator. Which part are you shaking around? Generally if shaking something makes it work, there is a bad or dirty connection, bad connector, broken wire, etc..

 

You might want to check your grounds, particularly battery to chassis. That'll raise heck with voltage regulation too.
The low wiper fluid thing is probably slosh in the tank. Mine does it starting at 3/4 full and gets worse as the level gets lower.

 

I read that the grounds and other connections can cause problems so I cleaned all of them I can find the one by the battery and the one on the fire wall. I also in bolted all the fittings on the alternator and cleaned them. The black wire going to my alternator goes into a black box that looks to be part of the wire than has 2 tabs on the top and to cables coming out that all bolt to the alternator and when I tap or poke at those connections my voltage climbs to 14 volts. I'm going to try to work on it some more today.

 

Well I took the alternator off today and had it tested and it failed. Weather permitting I'm going to put the new one on after lunch but I'm still not sure what this black box is? It looks like the side of it is sunk in like it got hot or something anyone shed some light on the matter.

 

Pretty sure its just there for identification purpose so correct wire gets put on alt post id cut it off and reclamp a new connector myself .....

 

The black box is the Power Distribution Center (PDC). If you unsnap the lid and remove it you can see relays and fuses.

You can remove the small plastic cover on the end of it (towards the radiator), there you can see two power cables hook up there. One is from the battery anbd the other is from the alternator. Take a look at the connections and see if they are corroded.

 

Here's photos of the ground points in your engine bay.











Here's a photo of the PDC:

 

I cleaned all those connections and had a slight improvement for a day than the same issues again. I installed a new alternator between rain showers and it seems to have fixed my voltage issue only time will tell

 

Just an update alternator seems to have fixed my voltage issue and my sputtering at low speeds is gone which I'm assuming the new crank position sensor fixed. Now I just have to figure out my turn signal issues