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always something...failing alternator?

outlander

NAXJA Forum User
Location
Columbus,Ohio
89 xj 5speed 4l
Driving home from work tonight i noticed my dash lights and headlights flickering and going dim and then back to normal every two seconds or so....thought maybe I had a bad ground but haven't been able to look into it because im so tired from working 12hr days not to mention its cold as hell out.

I wonder if this can be symptoms of a failing alternator?My aftermarket volt gauge was going nuts from as high as 14.6 down to 13.8volts off and on.
Battery is brand new....less than a month old so thats ruled out
 
was your defrost on? it will turn your ac pump on and could be the culprit. with my 89 i definitely notice when that sucker kicks on. it doesn't quite stutter but you can tell there is a draw which could cause a breif slowing down of alt.

never had ac on at night though.
 
Start by REFRESHING those grounds.

Renix (87-90) are especially susceptible to electrical gremlins with a flaky ground. You must actually disassemble them, clean them until shiny and reassemble Can't tell jack crap by looking at them.

After that, the #1 suspect would be the alternator.
 
Start by REFRESHING those grounds.

Renix (87-90) are especially susceptible to electrical gremlins with a flaky ground. You must actually disassemble them, clean them until shiny and reassemble Can't tell jack crap by looking at them.

After that, the #1 suspect would be the alternator.


Couldn't agree more. Especially in rust-belt areas this should be number one priority.

Heck, I live in arizona and have rust-free Jeeps and their grounds get crappy. I can only imagine what yours are like.
 
I doubt it's a failing alternator if it only drops to 13.8. Usually when the alternator starts going it will drop right down below residual battery voltage. I'd check wiring, and consider the headlight switch itself as a suspect.
 
Yeah, check the back of the headlight switch for a burnt or hot connector.

The best cure for the bad headlight switch design, imho, is to install headlight relays and a beefed up wiring harness fed from a fuse connection directly to the battery. You'll see a noticeable improvement just from eliminating a volt of drop through the stock undersized wiring and switch.

This will also set you up nicely for upgrading the headlights. The link below is for the E-Code AutoPal headlights. They aren't $300 PIAAs, but they are a huge improvement over stock sealed beam bulbs for $40 shipped. I would suggest skipping the ultra-blue bulbs and go with the regular white 55/100 or 80/100 H4 bulbs. I run these with the 80/100 Napa house brand bulbs at $8 each in my MJ. The cutoff is great and I never get flashed with the lows and the highbeams really light up the road (great for spotting those errand deer and moose at night).

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330397530440
 
if you had the blower motor on check the flat brown connector at the back of the HVAC controls. I bet you'll find it half melted and burnt. the blower motor will make the voltage guage bounce around because of the substandard ground that everything in the dash is connectoed too.

Blame AMC, they couldn't wire a vehicle for crap.
 
I've had the dash lights dimming on me recently no other lights. I have an HD headlight harness and HID fogs with an HD harness also and they don't dim/flicker at all. It's weird that just my dash lights will dim slightly every few seconds. My volt gauge doesn't jump around at all.

Could it be the dimmer switch or maybe even just failing dash light bulbs?

97 4.0 with newish battery and 5-90 battery cables all grounds are fine(cleaned).
 
Ill look at the headlight switch but it is fairly new...

Don't have AC....

Heater wasn't on....

Headlights are already wired through an aftermarket loom and relays(makes me tend to rule out headlight switch)

Exactly where are the grounds that need to be cleaned on the renix bastard???
I want to get them all.....along with cps bypass of the c101
 
Ill look at the headlight switch but it is fairly new...

Don't have AC....

Heater wasn't on....

Headlights are already wired through an aftermarket loom and relays(makes me tend to rule out headlight switch)

Exactly where are the grounds that need to be cleaned on the renix bastard???
I want to get them all.....along with cps bypass of the c101

one from the head t the firewall.

You should add one bonding the alternator directly to the battery, then bond that cable to the body.
Should be one in the back for the fuel pump.

That's the major ones. Theere's on on the drivers side of the dash under there, it's really undersized. Double it up or replace it with 10 guage wire.
 
Batt to block.

Head to firewall (POS braided strap, replace with 4 or 2 gauge cable).

Dipstick tube (ECU, ICM, o2 sensor, others).

As stated, adding an alternator/batt/fenderwell cable will help.

Article on improving Renix charging: http://www.olypen.com/craigh/charge.htm

Those are the big ones. There are other grounds for lights, fuel pump, under the dash.

Your 89 shouldn't have the C101 connector, its last year was supposed to have been 88. The C101 connector is right on top of the brake booster--do you have one there?

The fuse block on the Renix is problematic for a number of reasons. If the brake or clutch MC leaks internally fluid runs down and "eats" the fuse block with bad results. Also, the crap that was put in them from the factory dries out and plays hob with things, and years of accumulating dust etc. doesn't help. It is a solid idea to pull the fuse block apart and clean it out and put some dielectric grease in there.
 
Thanks for all the help guys.
I have an alt bonding strap along with welding cable battery cables...been meaning to get around to running a cable from the neg post to frame....
Thanks again......
 
O and I guess I done have the imfamous c101

Ok, but the TSB for the CPS wiring mod was done all the way up to 90, so still not a bad idea to do it.
 
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ive been working on cleaning up grounds today and decided to do a voltage check with motor running volts at battery were 15v.....high?
Guess ill take it down to the parts store and have them hook their machine up to it and diagnose...
 
one from the head t the firewall.

You should add one bonding the alternator directly to the battery, then bond that cable to the body.
Should be one in the back for the fuel pump.

That's the major ones. Theere's on on the drivers side of the dash under there, it's really undersized. Double it up or replace it with 10 guage wire.

what is the that ground for under the dash?anyone have a link on adding grounds to sensors to be sure they are operating properly?
 
what is the that ground for under the dash?anyone have a link on adding grounds to sensors to be sure they are operating properly?

There are a few grounds under the dash--instrument panel, others.

You should use your ohm meter to measure the resistance on all of the sensors to see if the resistance is too high, indicating poor connection.
 
where is the heater blower ground?87 manche mentioned running a bigger ground there....my voltage drops really low with the heater on high
Does 15v seem like too much voltage at the battery?
 
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