Fuel Gauge Modification

[LJ-TJ]

My stock fuel gauge on the instrument panel isn't working.  Is it possible to take an after market fuel gauge and hook it up to the existing sending unit and bypass the gauge on the instrument panel?  If so, how can it be done? Thanks guys ya never let me down yet.  T.J.

[Arberg0]

HI LJ-TJ

I seem to remember it can be done but it all depends on the sort of sender unit in the tank if you choose the wrong type of gauge the reading will be out i have seen this before in the UK on a van i had it said half full and it was empty .its all got to do with a rheostat type unit in the tank that sends the correct signal to that little meter on your dash did i not here you say you had got a spare dash last week when you had that wiring issue is there not a fuel gauge on that


arberg 0 aka William

[LJ-TJ]

Yeh! got the hole wireing harness as well as the insterment panel. Just not sure where to go from here. .

[tomr]

This is likely not the way you want to go, or it may not even be practical, but Princess Auto has a gauge and "sending unit" on sale right now.

http://www.princessauto.com/truck-trailer/electrical/12-volt-gauges/4230140-fuel-level-gauge?keyword=fuel+gauge

http://www.princessauto.com/truck-trailer/electrical/12-volt-gauges/4230157-fuel-level-sending-unit?keyword=fuel+gauge

The sending unit "Fits fuel tanks from 5" to 23-1/2" deep"...

Tom

[LJ-TJ]

I think I'll give it a whirle.

[DaveVA78Chieftain]

I am going into all this because it may not be a gauge problem.
What you have to consider with this area is that Dodge designed the fuel indicator circuit for only 1 tank with the ability to add a 2nd gauge to the instrument panel (74 and later).  Winnebago did not add a gauge.  They opted to redesign the circuit so that the Main/Aux tank select switch controlled not only the tank select valve, but also the tank level circuit.
So the first question is: Is the problem the gauge, the select switch circuit, or the wiring?

If the select switch, then is it a 5 pin or 2 pin switch?  (Winnebago lists switches in their catalog)
2 pin select switch (SPST) would drive a relay and possibly the select valve.  Relay would select which tank (Main/Aux) level sender feeds the gauge.  A second circuit on the relay could drive the valve.
5 pin select switch (DPST) would be split.  One side provides signal to the valve; other side selects which level sender feeds the gauge.

If the gauge is the issue then if memory serves me correctly, you need a 75-10 ohm aftermarket type gauge.  You may have to measure the resistance of your sending unit to ensure correct gauge selection.

I have had the pins on the instrument panel printed circuit board (74 up) break off.  Be careful with that board.

All stock Dodge fuel/temperature meters use a 5VDC constant voltage regulator.  For 73 and earlier (old style instrument cluster), the 5V source is built into the fuel gauge.  For 74 and later (new style instrument cluster), the 5V source is installed on the printed circuit board.  Aftermarket add-on gauges use a 12VDC source.

[Oz]

In addition, you may get some ideas from 2 items in the Tech Resources section.  One is troubleshooting fuel gauges and the other is an article on a primary electrical component which is often the cause of gauge problems and how to easily upgrade it.