fuse block.

i have a 91 cherokee sport.
the fuse block under the dash has a plug on it that is labeled power
other jeeps i have looked at have a wire going into the harness
on mine there is a wire going from the plug labeled power to a switch on the bottom of the dash and the from the switch threw the firewall and it was grounded out on the headers.

i cant find anything online telling me what that plug on the fuseblock is for.

From your description not sure it is OEM.

Can you post up some pictures?

its the plug highlighted in red. i have looked in other jeeps and there is a wire going into it from the harness. on my it was wired to a switch which then went out threw the firewall and was grounded out on my headers.

Off to sleep, I will look in the electrical FSM tomorrow.

Can't think of a good reason to ground something to a header.

The closest I have is a 93 FSM and that spot is "UNUSED". If that is accurate for the 91, then the wire and switch are not OEM, and there is no way for anyone on or any other board to tell you what it is for.

Do you have any problems, other than the shorting out?

well when i turn my blinkers on the clock flashes with it.. probably a short?
my horn no longer works.
my battery keeps dying and the jeep is running rough
it was idling really low around 300 and missfiring and backfiring.
and if you gave it gas it would want to die. if you gave it alot of gas it would slowly start moving.
so i took it to a shop and he said it was an ignition wire (i couldnt figure it out to save my life)
i drove it for a day and it ran great, until my buddy totaled his car and asked me to come pull it out. i was about 100ft from the accident and the thing started acting up again.

i found out i cant adjust the timing with the distributor im new to jeeps.
the mechanic said my distributor and coil were fine (i have a mallory coil)

any ideas?

CharlesS said:

Can't think of a good reason to ground something to a header.

Click to expand...

I think it was connected to something else and the connection broke and the wire ended up stuck to the header when it shorted out on it.

I would disconnect that wire--you have probably already done that.

Ok, get your battery fully charged, and have it load tested--doesn't matter how old it is.

Now, FYI, low battery will make the engine management go wonky on you. When available voltage drops below 9 volts the electronics can't operate correct.

While the battery is charging clean both ends of the main cables. Renew your grounds, with particular attention to the POS braided strap from the rear of the head to the firewall. Clean all metal surfaces down to bare metal, treat with an anti-corrosion agent, and make the connections TIGHT. Best to replace that POS braided strap with a 4 or 2 ga. cable.

Ok, battery fully charge and passed a load test (or replaced), everything hooked back up, attach a voltmeter to the battery terminals--should have about 12.5 volts static. Now start the engine and re-read the voltage, should be 13.1 to 15.3 (there is a an ambient temperature chart with voltage ranges).

Here is the best article I have found on upgrading the XJ charging. Most of it is Renix centered, but it applies to all years and the bottom of the article is 91+ info: http://www.olypen.com/craigh/charge.htm

Post up what you find out.

PS--most of your running problems sound like the result of low voltage.

PPS--Welcome to !

yes i did disconnect the wire, and i will probably replace the battery and do everything else you said.

i just realized the battery that is currently in the jeep is bigger than a stock XJ battery so the ground post is hitting the inner support of the hood right next to the passenger side latch.

also there use to be a alternator in the jeep that was bigger than stock. and the previouse owner had rigged up some brackets out of angle iron.. these broke. so i got a good stock alternator and the stock mounting brackets. but now the new alternator has a wheather pack on it which i have no idea what it goes to. no clue but i was looking at it and there are some unplugged wires hanging by the alternator that go up to my mallory coil. any chance they are related?

Thanks for the help!

Well, the stock Nippon Denso in the 91+ XJs are regulated by the PCM.

Just how much of a hack job did the PO do?

how big of a difference would the alternator not beeing connected to the PCM would it make? would it cause the missfiring issues or just the battery not holding a charge?

and it is pretty hacked up. got weird wires everywhere for the ignition system the malory coil was installed funky with janked up homemade harnes speaker wire everywhere.. i didnt notice all of it at first.

i have found that there is a short somewhere but have no idea where to begin looking.

Thanks,
Mitch

Without the PCM connection the alternator will not charge the battery. Low battery power, less than 9 volts, and engine management suffers so if the alternator isn't keeping available voltage up all kinds of issues will present.

Your best bet is to get your hands on a FSM--factory service manual--for the 91. That way you can trouble shoot by wire colors.

FSM on CD available here: http://www.autobooksbishko.com/index.html for about $37 bucks, they are licensed copies. They also have the book manuals as reprints, about $100 for a set.

thanks, i am probably going to just take it up to the shop i originally had it "fixed" at i dont have time to fiddle with it as school is going to be consuming alot of time.

but i will certainly give him the information you have given me and i figured out and hopefully he can get it fixed quicker than me

Thanks,
Mitch

Ok, good luck.