GAUGES 1990 Trooper Fuel/ Water Temp Gauges don't work?

[TroopsTrooper]

Has anyone ever seen this problem?

Both sending units appear to be fine. Both functioned earlier today. All ground wires and, for that matter, all wiring, appears to be intact and fine.

Fuses are fine, etc.. My cluster has 3 gauges; oil press., fuel qty and water temp. Oil works great, fuel shows nothing, water shows nothing. All show panel lighting, etc.. AND as all three share earth/ground, shouldn't they all work - just like the oil pressure gauge does?

Aaarggh.

Thanks for any help you can give,

Kevin

[atfdmike]

Hi, I have not worked on a Trupr II, but it does sound weird that they would quit at same time. I would definitely look at the cluster for the problem, maybe loose connector or such. Here is schematic, hope it helps or spurs others to offer suggestions.

[TroopsTrooper]

Hi, yep, I removed the cluster, researched the harness and all seems good.. like new in fact. I tried the ohm test across the fuel gauge, but it didn't show the 25ohms, suggested by the tech manual.. w/ign, w/o ign, etc..

My next stop is the dealer.. man, that'll hurt.

thanks for the reply though and yep, you're right, two gauges to go out at the same time suggests that it isn't the gauge, but more likely a ground, or short someplace? The gauge cluster shares ground through the Voltage regualtor, which I haven't quite located yet.... wish I were a smarter guy.

Kevin

[TroopsTrooper]

Further to that.... I may have spoken too soon. I hopped in the Trooper today and everything worked as designed. I drove it a short way and when I got back in to leave, they didn't work again.

I know - sounds like a grounding issue, but I checked the wire runs and the grounds are tight. AND wiring appears sound w/o soft spots, etc. I wonder if there is a capacitor someplace - inline - that is loading up and cancelling signal to the cluster, then, overtime, discharging causing them to work again??? Just random thoughts.

I really want to avoid the dealer.

Any guesses/?

thanks, Kevin

[atfdmike]

Sorry, no good guesses. the schematic does not detail the circuits within the solid state circuits, but if the cluster is out of dash, can you check to see if there is voltage at the gauges? Where that leaves you, I can't guess. Intermittents are a pita.

[Tryumph]

The same thing (almost) has been happening on my '89 for at least two years. The fuel gauge and temp gauge won't work (typically, when car is first turned on). Sometimes they come on after a few minutes of driving, or a half hour, but sometimes not at all. However (and this is the strange part) the oil pressure gauge ALWAYS works.

I took apart the gauge cluster, checked for presence of a power signal at each gauge and all were fine. I did loosen the nuts on the power-carrying terminals and add some vaseline (poor man's electrical booster) to ensure good electrical contact.

Also, the grounds seem OK. The one thing that I haven't done is checked the total resistance of the ground circuit, because I don't know where it ends up. That should probably be my next step -- I have been using a body ground to do the testing for convenience purposes.

By the way, I'm pretty sure that the "low fuel" warning light is on a separate circuit, because it HAS come on even when the other gauges were being problematic.

On more sophisticated cars, such problems are often caused by aging capacitors or solder joints that "go bad" due to repeated heat-cool cycles. I don't know if either could be a possibility here.