Fuel gauge for aux tank not working

lip · October 30, 2016, 04:27 AM

Hello Everyone,

I have the following issue: Since I've installed new brake lines in the rig, my fuel gauge for the aux tank doesn't show anything. The standard tank is working.
Can anybody give me an advice how to start troubleshooting? It would help to know how wires are linked. is there a wire from each sending unit to the switch in the dash panel?
Thank you in advance for your help.

Best regards from Germany,
Lloyd
(1976 Brave M400)

Rickf1985 · October 30, 2016, 11:35 AM

Since this happened after you did the brake lines be sure to look in the area of the brake lines for any wires you may have disturbed in the process. 99% of the time a problem like this is the result of the last thing done.

lip · March 29, 2017, 03:16 PM

Problem is solved. The cable was rusted away on top of the tank. With thin and flexible arms it was fixed easily. Thanks for your help!

NiftyBetty · March 29, 2017, 05:10 PM

I have a 1975 D19, but not with the originaol engine. Fuel gauge does not work at all. Mechanic said he thinks the problem is in the gas tank, and he'd have to drain gas, disassemble, etc., to diagnose and hopefully fix. Does this sounds right to you? I know some of the older cars had some kind of "float" in the gas tank to measure the level. What are the likely reasons the fuel gauge would be dead? Any cures that are cheaper and easier that don't require a mechanic that charges $90 an hour?

P,S. I believe I checked the forum before about this and did not find anything. If I missed it, I hope the mighty OZ will forgive me.

LJ-TJ · March 29, 2017, 05:45 PM

Well! D:oH! I got a 1975 21footer and for years had trouble with my fuel gauges. You could check to see if it's a bad ground. I just said the heck with it a bought to autometer fuel gauges and installed them. However the fuel sending is installed on the top of the fuel tank and it's a son of a gun to get at. You pretty much have to drop the fuel tank to get at it and that's not the easiest job. With hind sight being 20/20 I'd locate the sending unit on the top of the tank. I'd then take those measurements go inside the rig and do the measurements and then take a good quality hole saw and drill down through the floor. You could then unscrew the sending unit install a sending unit or install an after market gauge.

Rickf1985 · March 29, 2017, 07:45 PM

If, and this is a big IF, you can reach the wire at the sending unit where it attaches to the tank and ground out that wire the gauge should go to full. If it does then the problem is definitely in the tank. But one thing to be sure to check is the ground connection from the tank sending unit to the frame. If this is broken ir dirty at the connection it will not work. This is all assuming you can even get to these wires which is impossible on a lot of them without dropping the tank.

DaveVA78Chieftain · March 29, 2017, 07:54 PM

Possibilities (from gauge to tank order):
1) Defective Gauge
2) Defective voltage Regulator on rear of Instrument Cluster (Water Temp gauge would also not work)
3) Broken connector or pin at rear of instrument cluster (common issue)
4) Corroded pin in connector at base of steering column
5) Bad connection at tank sending unit
6) Bad ground at Sending Unit. As Rick said, grounding the wire reults in "F" reading at the gauge. Doing that anywhere along the path has the same effect.
7) Bad Sending Unit (Dodge is a 10 ohm - 70 ohm unit)
8) Float for tank sender unit could have a hole in it and no longer floats

One needs the wiring diagram to T/S this.

Rickf1985 · March 29, 2017, 07:58 PM

Dave is always showing me up! :)rotflmao :)rotflmao :)rotflmao

DaveVA78Chieftain · March 29, 2017, 07:59 PM

LOL - Lets just say I have the circuit memorized from past experience is all. She at least does not have to account for Dual Tanks.

Thenoob · March 29, 2017, 08:11 PM

Lol same here

My 73 d19 dodge has always been stuck on empty, crawled under today and said, crap, might have to drop this thing.

I did notice the braces for the tank are starting to bend at each of the bolts. Which kinda freaked me out.

Thing I hate most is electrical, I'm horrible at it and it musher be a job to source out some help to show me.

C&T2 · March 29, 2017, 10:24 PM

I don't remember where I stumbled across this ~~Winnebago Fuel Gauge Troubleshooting~~ PDF - if it was someone/somewhere here my apologies! W%

Sorry, the quality isn't the greatest, but it looks to lay out sound advice for getting your fuel gauges working again... I'm hoping to walk through the steps myself for a non-functioning auxiliary fuel gauge that is driving me nuts!

Thenoob · March 30, 2017, 09:49 AM

Holy this is awesome!!!
Thank you thank you!!

turbinebronze · March 30, 2017, 12:19 PM

It was mentioned in a earlier post that grounding the fuel gauge wire will give you a full reading on the Dodge, which is correct....but, if you do it for any length of time you will let the magic smoke out of the gauge. The Chrysler fuel and water temp gauges are heat activated, the GM gauges are magnetic. If you check a Dodge gauge by grounding the sending unit wire, do so just to check for movement. Don't leave the wire grounded. You can burn out the gauge.
Just my 2 cents, Craig.

NiftyBetty · March 30, 2017, 03:18 PM

Great stuff. I will talk through this with my mechanic. Thanks!

Rickf1985 · March 30, 2017, 07:51 PM

Quote from: turbinebronze on March 30, 2017, 12:19 PM
It was mentioned in a earlier post that grounding the fuel gauge wire will give you a full reading on the Dodge, which is correct....but, if you do it for any length of time you will let the magic smoke out of the gauge. The Chrysler fuel and water temp gauges are heat activated, the GM gauges are magnetic. If you check a Dodge gauge by grounding the sending unit wire, do so just to check for movement. Don't leave the wire grounded. You can burn out the gauge.
Just my 2 cents, Craig.

Good info, and that goes for testing any gauge on any brand, do NOT leave it that way!

Sometimes I forget to add the things in that are obvious to me not thinking that the average Joe who is not a mechanic would not know that.

Thenoob · March 30, 2017, 07:59 PM

I'm horrible with electrical it intimidates me but I think I can handle the most of it.

Well written! For the dumb guy!!

stanDman111 · March 30, 2017, 08:59 PM

the only dumb guy, is the one that doesn't ask the question

DaveVA78Chieftain · April 01, 2017, 12:34 AM

QuoteI don't remember where I stumbled across this Winnebago Fuel Gauge Troubleshooting PDF - if it was someone/somewhere here my apologies!

It is one of the resources in members area of this site. That is the advantage of being a member of this site.

C&T2 · April 01, 2017, 10:18 AM

Quote from: DaveVA78Chieftain on April 01, 2017, 12:34 AM
It is one of the resources in members area of this site. That is the advantage of being a member of this site.

Oops - so sorry! Yeah, logged in and there it was. Damnit... Have pulled the document down... Curse me and my terrible memory.

(I honestly don't know how some of you guys remember all of this stuff!)

So folks, it is really, really worth the couple of membership $$$ to get access to the amazing documentation that lies under the hood here. It helps support this amazing online resource we all call home - websites don't run for free!

Froggy1936 · April 01, 2017, 12:39 PM

Memory is a very funny thing, Hm? I get surprises when i re read some of my old posts , He He I dont remember that at all even though i wrote it D:oH! ! Happens a lot !! i?? i?? i?? Frank

DaveVA78Chieftain · April 01, 2017, 02:12 PM

Quote(I honestly don't know how some of you guys remember all of this stuff!)

W%
I designed, built, and maintain those web pages for Mark so yes, I know what is there.