temp guage fail

[notlyingdown]

85 CJ7 5 speed carbureted straight six 116,000miles
While looking into why the "4 wheel drive" light was not coming on in the speedometer cluster anymore when shifting to 4WD, I heard a distinctive pop as if a fuse blew (I might have crossed something) and then observed that the engine temp gauge (in the same speedometer cluster) stopped working. I checked all the fuses I could find and all are good. Is there another fuse somewhere for the temp gauge, or could it have been the actual gauge itself popping/frying?
As far as the "4 wheel drive" light, where is the sending unit/switch for that?
Would appreciate any/all input. Getting a little frustrated with the little electrical problems that seem to have been popping up lately. I put the oil pressure gauge problem on the back burner to take care of these first.
Thanks

 

[Torxhead]

In your CJ, the temp gauge is protected by the ign/lps fuse, as per the owners manual is a 15 amp fuse. Personally, I think it should be around a 3 amp as it is for the computer, fuel & temp gauge, oil pressure gauge, and 4wd indicator. A heavier fuse could fry the gauge with a short. A fuse blowing should not "Pop" either. The big box 4wd outfits do have replacement gauges. For more info on gauges look for John Strenk's New Gauge Page on the net.

 

[notlyingdown]

I will look again for the "ign/lps" fuse. If its for "the computer, fuel & temp gauge, oil pressure gauge, and 4wd indicator" and its fried, the fuel gauge and oil pressure should not be working. The fuel gauge works fine and the oil gauge is bouncing around (as mentioned I need to look into that) but its movement seems to show no burnt out fuse problem? I"ll look into it again tomorrow. Might just do the whole replacement angle through John Strenk's. Thanks for the info. Will F/U

 

[notlyingdown]

Torxhead, thanks for the info. Looking at John Strenks page and a couple hours of troubleshooting solved the Temp gauge problem. I'm working on the oil gauge now. It reads normal when first started up, but after about 20 mins of driving almost always starts fluttering around and eventually ends up staying around 0 to 5 psi. The gauge and sender are new and everything worked fine for a couple months, now this. Maybe a grounding problem affected by heat somewhere?
Also got the "4 wheel drive" activation light not working. Bulb is OK. I take it that it has a switch or sending unit somewhere around the Transmission /Transfer Case ?

 

[notlyingdown]

Got "4Wheel Drive" light working. Ended up being a three lead plug that needed cleaning and a little tighter reassembly.
The oil gauge is still a mystery. After driving for about 20 minutes it went to 0-5 psi (as is what has been happening) and just stayed there no matter what RPM. While idling, I decided to disconnect the wire that snaps to the top of the sending unit and quickly ground it to the negative battery terminal (about two seconds) and it pegged. Reconnected the proper lead back to the top of the sending unit and the gauge was reading again, not accurately but the same as just before driving it around the prior twenty minutes and it dropping down.
Would giving the gauge that jolt and having that effect point to a gauge problem, or could it still be a ground problem or maybe even a sender problem.

 

[DHugg]

Notlyingdown, can you be specific about the "no temp gauge" fix? I have had the same trouble since bringing my Jeep home. Been through the Strenk trouble-shooting guide without result.

 

[notlyingdown]

My "temp gauge fail" ended up being embarrassingly simple. While poking around looking to fix my oil gauge problems, I "pulled a plug" so to speak hooked to the temp gauge. Popped it back and it was back to normal. That probably doesn't help you out too much. I only got through half Strenk's troubleshooting before I spotted the problem. You actually went through the whole procedure, and nothing?
The "4 wheel drive" light problem also ended up being a plug problem but not so obvious. I'm back to figuring out the oil pressure readings issue now.