You have several sets of grounds under the hood - and they will cause some funky behavior when they are corroded or gunked up - ask me how I know........

1. chassis ground - by the battery
2. engine ground - from battery (-) to coil mount
3. sensor grounds - harness to coil mount
4. sensor grounds - main harness to oil dipstick mount
5. PCM grounds - next to PCM on drivers side
6. ground strap from cyl. head to firewall

Scotchbrite or steel wool and brake cleaner is all you need. Cleaning them took my '93 from sputtering, stalling, leaving me in the middle of ATL rush traffic, and generally pissing me off, to running like a champ again.


It cant hurt to clean them, and it doesn't cost anything.


As far as the wire upgrade, I did 2AWG for +, -, and ALT. 4AWG to the starter. Marine grade cable, soldered lugs, and adhesive shrink tubed. I bypassed the PDC on the charge wire and went straight to the battery - I didn't want to mess with splitting 2AWG into the factory ALT wires to the PDC, and I already have a 2AWG cable going from the battery to the PDC.


Worthwhile upgrades

 

Definitely do 5-90s upgrade. Well well worth it

 

Open the link below and scroll down to post #49. It shows the ground points in your 1998 XJ engine bay. These are the ground points you want to disassemble, remove corrosion, and resecure.

Do not use Dielectric grease on these grounds.

https://www.cherokeeforum.com/f2/gre...e-6558/index4/

As well as the ground points, inspect the power points in the engine bay. Connection at the starter and the connection on the bus bar at the end of the PDC.

Personally, I see no point in changing the factory cabling in the engine bay to a heavier gauge cable. If you have lots of current draw mods then it may be a good idea, otherwie there's no advantage.

 

Ok OP, you need to stop reading all of these posts until you can actually troubshoot. By reading this stuff before you can do it at the same time, yore gonna hear hoofs and look for a unicorn when its really a horse.

I mean is, go home and start simple. Check the grounds and the main cables and ALL of their conditions. Bad wires can cause these issues. After you check the wires, then get the battery and alternator load tested. Do these things and then ask for further help.

 

Troubleshooting is the first thing I did when I got home since it was actually light out After poking around a bit found the fusable link had blown up, not burned out, blew up. 5-90 didn't answer my message so ordered a new 4 ga alternator wire from CustomBatteryCables.com and figured while I'm at it also order the 1/0 ground and power wire upgrade with military terminals, with 2 day shipping set me back about $180, sounds like a worth while upgrade though (and the alternator wire a necessary one).

But I do thank everyone here, I would have never thought of the wire failure, saved me from tearing the alternator back out... parts on order battery on charger as we speak

 

With that heavy gauge wire what are you going to use for a fusible link? You do need a fusible link, or equivalent.

 

Now that you upgraded yes, that wiring is very important. Like just mentioned,you need to upgraded that link too.

 

Also, put a multimeter on the positive terminal of the altnerator and ground it to the engine block -- check voltage.

Do the same thing at the battery cable to make sure the fusible link and wires are still good - you should have a very similar reading at both points.

Check the alternator voltage at idle with no load, at idle with lots of electrical load, and at 1500rpm with lots of load. All should be pretty similar as well, and anything less than 13v indicates a charging issue IMO. Should be reading ~14v if everything is working properly.

 

Won't an appropriately sized ANL or Mega fuse take the place of the fusible link in the wire from alt to battery?

 

4awg wire and the 136a alternator will work very good with a 150a fuse

 

I hate to chime in so late, but when my son's xj started having issues we found the there was a fuse (rely) in the fuse box in the engine bay that was faulty. replaced it with a new one and bam problem solved. It has been good for 6 months and going strong.

 

Tell us...

 

Do you have data to substantiate this?

 

A fusible link is an ancient technology fuse. A slo-blo fuse and some circuit breakers will mimic the operation of a fusible link.

I have all of the materials to replace the battery and alt to battery cables with 2 gauge stock and a Mega fuse.

We can always debate whether the stock XJ needs upgraded wiring but I don't believe it can ever hurt to do so. Does it need 2 gauge? No, but I'm doing my own work (if I ever get to it) and cost is manageable using top grade components including marine grade wire. Jon Kelley (5-90) suggests using a fuse with his kits. For whatever reason, I prefer Mega fuses to the ANL he uses, but I haven't heard negative feedback as respect his work.

We're here to learn. Let us know if we are missing something.

 

I have about 0 knowledge about alternators and this could be totally irrelevant to your prob, but my locks started going haywire and I let them go for a few weeks. Finally had a no start day (battery) and when I checked, battery was drawing about 2 amps when xj was totally shut down with doors closed, etc. Narrowed it down to pssgr power window / lock fuse (#16 IIRC...a 25 amp one. I took that out, charged battery and had no further voltage issues.