gauges started acting weird

[will e]

82 cherokee.
Temp, oil, gas guages all started acting weird during a wheeling trip.
Sometimes they don't appear to work at all.
Sitting in the driveway yesterday with the engine off and the ignition on the gas and water temp would move up what was probably the correct position and then pulse down a little bit and then back up and then back down.

I am thinking guage voltage regulator? I really don't want to pull the gauges. I assume the cluster unscrews. How hard is it to get the speedo cable off?

[rstep]

Check the grounds first Mike IIRC they are up high on the left side under dash.Pulling the gauges is last drop steering colum some and if you can go in threw the glove box to get to the speedo ,also remember the heater,vent cable and vac lines.

[letank]

82 cherokee.
Temp, oil, gas guages all started acting weird during a wheeling trip.
Sometimes they don't appear to work at all.
Sitting in the driveway yesterday with the engine off and the ignition on the gas and water temp would move up what was probably the correct position and then pulse down a little bit and then back up and then back down.

I am thinking guage voltage regulator? I really don't want to pull the gauges. I assume the cluster unscrews. How hard is it to get the speedo cable off?

The pulsing is normal, the CVR is going off and on. there is a very detailled troubleshooting method on the TSM for the 79 listed in tom's ol jeep site

http://oljeep.com/edge_parts_man.html

If no AC it is not too bad to remove the speedo cable, you only have to lay in a weird position, not good for tall creatures...

as said, check grounds , or add extra ground, may be engine ground to frame strap/cable

[will e]

Of course today they worked perfectly without issue. I am planning on going with some aftermarket gauges at some point. I hate the ambiguity of the stock gauges. I know what is 'normal' but it would be nice to have something a bit more precise.

I am leaning towards the ground being the issue. I was able to giggle the wires a bit yesterday and the gauges started working. If the ground is bad, what other indicators would there be?

[ShagWagon]

If you can jiggle and isolate, then you can trace it down and look for damage on the wire or connector.

[tgreese]

The factory gauges work well if you replace the goofy vibrator 5V voltage regulator with a 7805 integrated circuit. IIRC this is discused in several posts on the mother ship. I should have documented my installation ... but I did not. The 7805 has the advantage that if you lose a ground connection, it does not conduct. This protects your gauges. The vibrator goes to full voltage if it loses ground ... could smoke your gauges. Has happened.

[letank]

As Tim said, I did the 7805 last year... it is documented on this site... can add link later.
bad ground pin on the printed circuit of the gauges from the oil sending plug on the passenger side of the cluster

et voila

http://www.fsjnetwork.com/forum/viewtop ... 4&start=20



green is ground and connected to the heater fan switch ground which is a separate ground than the one on the oil pressure side molex connector

[az chip]

Where did you ground the new USB charger?

[will e]

I actually have a 5v converter I installed for the digital volt gauge. I am thinking I can use that for the gas/oil/temp gauge. I will need to do more reading.