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Voltmeter variation

S

SuperGlue

NAXJA Forum User
Location
Forest Grove, OR
Hello everyone, my volt meter wont really stay out of the red anymore. A couple weeks ago, I replaced the alternator main wire and the lead from the batter + to the relay block thing. I also replaced my alternator at the same time, because I wanted to go from 60 amps to 100 anyways. I also replaced the ground braid with a 6 gauge wire, which is the same size I used for the alternator main. Even after all this my gauge still reads in the red, sometimes the bottom of the read sometimes the top but never above. Should I try cleaning the gauge cluster plug and terminals? Is there something I have overlooked? Thanks for any help in advance, this is an 89 by the way so its internally regulated if that makes a difference.
-Phil
 
Seen a few people mention they fixed that problem by cleaning out and regreaseing the main bulkhead connector... I'd be willing to bet you can find a writeup on it in a search.

Thinking an ignition switch was also a cause of that in another thread.
 
The main bulk head connector? Is that the huge one next to the break booster I believe? The c202 or something like that. Lights don't dim, words don't slow down. It acts all normal. I'll check it with a multi meter tomorrow and let you guys know what it says. Thanks!
 
The question I would like to ask is, what is the actual voltage at the battery with the engine idling?

It would be good to know what the ambient air temperature is when you take the voltage reading as well.

The Alternator was replaced so that fairly well eliminates the Alternator as the source of the issue.

My suspicion is that the gauge in the cluster is a tad wonky. Certainly a clean and reseating of the cluster connectors is a good thing to do.
 
Alright, finally went out with a multimeter.

With the alternator I have had sense I bought it, which I can only assume is a 60 amp, im running 14.162 volts at the alt, and 14.160 at the battery.

With my new Duralast gold 100 amp,

14.171 at the alt and 14.170 at the battery.

So, I guess Im off to checking my gauge cluster and electrical connectors. The last time I took apart a main harness, which was my headlights, all the terminals broke and were so corroded that I just wound up making my own aftermarket headlight harness with some 30 amp relays and 10 gauge wire. Im afraid of taking that main connector apart for the same reason. If it all crumbles apart, will it be ok to just hard wire everything with crimps and shrink wrap?
 
The connector where the harness mates to the cluster is a common point for corrosion. Take it off and clean the flex circuit with a pencil eraser.
 
SuperGlue said:
Oh, and its 45 degrees where I live right now. Not sure why that would affect anything, but Im happy to learn. =D
Click to expand...


There is a sensor, located under the battery, that senses the battery temperature. This sensor feeds the temperature data to the PCM so as to help prevent overcharging the battery. A battery that is getting over charged will begin to run hot.

Also, at least in both the '97 I had and the '98 I have, the charge voltage is lower in the cold than in the warm.

As for my making a "Dangerous assumption". The statistical likelihood of two Alternators displaying this pretty definite error is not high...

And now, we have the actual voltage readings that back my assumption.

IMO, it is time to look closely at the cluster. The clusters have a history of idiomatic behaviors such as the speedometer stopping. Usually, cleaning the contacts on the back side of the cluster helps out.
 
I tracked it down to my fuse panel at the drivers feet. That entire box is so fried that almost all the fuses I have had to bend the blades so they make contact, and they are all corroded. My auto tech teacher from high school, (I have had this jeep for six years), told me that the manual renix xj's were notorious for the slave leaking, which is right above the fuse box. Then the hydro fluid eats away that box. What Im wondering is if anyone knows of a drop in wiring harness supplier? I cant seem to find one for a xj from painless.. Or maybe just a replacement fuse block? Thanks in advance!
-Phil
 
Not just the Renix -- I fought that battle for years with my '85 5-speed. (Beside the point but that's the master, not the slave.) I was always able to clean up the box in place and replace all the corroded fuses and it actually lasted the 20+ years I owned the thing.

I know that some have taken the box out and done a better job on it and there are old threads on this approach.

Sorry I don't have a better solution if your box is too far gone for this approach
 
What I would like to do, is buy a aftermarket fuse block that will fit in that cubby hole below my glove compartment. I found one from painless, but im unsure about how I would go about relocating the wire loom from the drivers foot to the passenger dash.. At the end of the day it will be far easier to just replace it where it is and fix it so that accessing it isnt neccasery on a regular basis. Does anyone know of a good wiring diagram for a 89 4.0 5 speed xj? I have looked in my chiltons and haynes without success. And googled but not having any luck. Any help is appreciated, thanks again!
-Phil
 
O-Gauge Steamer said:
There is a sensor, located under the battery, that senses the battery temperature. This sensor feeds the temperature data to the PCM so as to help prevent overcharging the battery. A battery that is getting over charged will begin to run hot.
Click to expand...

no such thing in the renix. Alternator is internally regulated and about as dumb as it can get.

The dash gauge pulls voltage readings from wiring that's inside the cabin.
if you have low voltage on the gauge and not under the hood you have a wiring problem under the dash.

Things I have personally had cause a low voltage on the gauge that were under dash related:
C101 connector. How I hate thee. pay particular attention to the two big orange wires on the top, those are the ones that bring in the power.
Renix fuse block soaked in brake fluid from clutch master. Caused all manner of corrosion on the back and wierdness.
There's a ground under the dash above your knee. When it's not good turning on electrical things inside will make the dash gauge do funny things. Electrical potential and all that.
Ignition switch and wiring burnt at the column.
 
SuperGlue said:
Does anyone know of a good wiring diagram for a 89 4.0 5 speed xj? I have looked in my chiltons and haynes without success. And googled but not having any luck. Any help is appreciated, thanks again!
-Phil
Click to expand...

there's a company authorized by chrysler to sell electronic copies of the FSM. I can't remember the name.

they're not terribly expensive, and will be the best investment you ever make to troubleshoot wiring in a renix.

AMC didn't exactly use logic when they wired a vehicle.
 
So, I unplugged the multi function switch from the base of the steering column. I was able to jump from the hot to every pin and either turn on the windshield wipers, the sprayer, but not the turn signals. Where else could the problem be?... A bad ground? I have had corroded plugs before, that caused the turn indicator to remain green always. At this time they do not blink or turn on at all... Any ideas? Thanks
-Phil
 
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