Gas & Temp gauge not reading correctly

[Arberg0]

From: panchokitty  (Original Message) Sent: 4/10/2002 10:22 PM

I drove my '77 Dodge Minnie Winnie for the first time from California to New Jersey in November.  I found out the gas gauge only registers half a tank exactly, and the temp gauge hardly reads anything.  Only once did the gas gauge go to full ( I would fill it up every time I stopped for gas, which was twice a day usually, 'cause I didn't know how much I really had).  Anyone ever see this?  Also, my turn signals work sporadically, both either working or not.  I figured it's the indicator, but who knows?  melissa   




HAL HERE.  I AM HAVING THE SAME PROBLEM WITH MY 79 BRAVE. HAVE TALKED WITH A DODGE MECH. HE SAID" IT WAS PROBROBLY THE SENDING UNIT INSIDE OF THE GAS TANKS. RECOMEND REMOVING THE SENDING UNITS FROM THE GAS TANK AND CLEANING THEM AND CHECKING THE FLOATS. EITHER THE FLOAT ARMS ARE STUCK OR THE FLOATS ARE BAD.
AS TO THE TURN SIGNALS, IT SOUNDS LIKE GREASE HAS GOTTEN ON THE CONTACT POINTS. I SPRAYED MINE WITH CONTACT CLEANER AND THEY ARE NOW WORKING.   



 
Also looks like since other gauges are involved, you might have a problem with a ground on the gauges.   Matt 





Given that both the fuel gauge and the temp gauge have problems, it sounds like your Voltage Limiter is not putting out the 7 volts to the gauges (or corroded wiring connections resulting in a voltage decrease).  See "Dodge Manual 4" in Boatnuts picture posting.  The electro-thermal design (Dodge Manual 2) of these gauges is what makes them slow responding to rapid changes.  I suspect the best way to think of it is in the form of a bi-metal strip that bends when heated (sort of like a hoousehold AC/heater thermostat, the coil expands when heated, contracts when cooled).  For the gauge, the greater the current flowing through the circuit, the more heat generated, the larger the fluctuation of the needle (i.e. Tank full).  Because it takes time to heat the internal element (thermal part) within the gauge, there is a delay in it's response.   dave76chieftain