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If the fuel gauge is not working, pull the sender wire and ground it to the tank, that should peg the fuel gauge if the gauge is good and the sender is bad, or if the float is sunk. If the gauge doesn’t move then you have a burned out fuel gauge and the limiter maybe on the way out if the temp gauge is acting erratic, however there is NO power to the oil gauge, unless it’s the late type gauge, and that gauge should have a tube that sends oil to the gauge that reads the oil pressure, I can’t help much there, excepting that it may have something to do with how cold your oil is vs. engine temp at any given time, you’re climate may have something to do with it.
Yes, as said, fuel gauge has voltage limiter built in and if it is fused the temp gauge will peg till it burns out, unplug the line that goes from the top of the fuel gauge before that happens; or if the temp gauge will not read at all the voltage limiter is burnt out "open". Now, are these black face gauges or white face? A good voltage limiter should pulse from 0 to 7 volts, higher than 7 volts and burnt gauges, less means low readings.... Gauges can be rebuilt, for a price, but the volt limiter can not, if you get the gauge rebuilt you must use a external limiter like what was used on car dashes.... Jeffc Ground the wire @ the sender unit & have someone watch the gauge. It should go to full. If it does, then after checking the tank ground, replace the sender unit. That is what I would do first. If no fix, then repost. Regards GB Britt, I’m not going into a lot of detail here, but here are the basic’s of the dash system on our trucks: Power Supply - from the battery wire to the back of alt gauge buss bar (red wire that is nutted on), the buss feeds most of the system (other nutted red wire on alt runs to starter relay). Buss bar-feeds fuel gauge and ign. switch and heater switch and feeds fuse box in most of our trucks(red wire from buss bar) (buss bar is feed by the alt gauge)(early trucks 60s did not always have fuse boxes) Fuel gauge - fuel gauge has volt limiter built in that supplies controlled voltage for both the fuel gauge and temp gauge (temp gauge feed wire is dark blue from fuel gauge “A” post to temp gauge “A” post, post on both gauges marked “S” are were the senders for each to hook to). Volt Limiter - If volt limiter fails it will ether allow full voltage to gauges, which will burn out the gauges, or will cause both to fail do to lack of a power supply, most often the first. In the first case, the gauges will peg, or read high, before the failure (burn out from high voltage). A voltage limiter can be placed between the buss and fuel gauge post, ether a car type (most 60s cars have one that plugs into the back of the dash) or one can be made from newer style parts (solid state). If a external limiter is used, do not allow it to ground to anything. Oil light - if not a gauge, light is supplied from the back of the ign. switch (black wire), sender side is orange wire and runs to sender (uses engine as a ground though the sender; temp sender works the same way, pays to have good engine ground wire to make that work right, to say nothing about the coil and distributor). Print it out and keep it around for future reference, sooner or later you will have to deal with something here. Well if that doesn’t tweak your head a little and you want more.. let me know. Jeffc P/N from Ferd is: COAZ9202B Float for Dodge Sending unit. My name is Beav. I have owned my own alternator and starter shop for 23 years. A one-wire alternator can run your amp gauge if you do the following. Run a 10 gauge wire from the alternator battery terminal into one side of your gauge and out of the other side of your gauge to a 12 volt source (bat), that’s it. Beav |