I have the instrument cluster pulled trying to figure out why my fuel guage isnt working. Well there are two wires connected to the cluster in the vicinity of the fuel guage. One is blue which connected to a pink wire that goes to the fuel tank. The other is red and has a connector on the end, but doesnt go anywhere. Does anyone know where this wire goes?
Thanks
Aaron

 

Perhaps you should say what year truck you have and whether you have a multi tank switch. I haven't had the cluster off my 69 but know it has a switch to switch between tank senders. My 76 and 79 don't have wires directly attached to the gauges, the gauge gets it's signal through a vinyl backing that has conductive pathways etched into it leading to a master wiring harness coupler. Could the disconnected wire go to switched 12V power? Or your tank selector switch? You do need to specify what year truck you have.

BBT

 

https://www.ford-trucks.com/dcforum/User_files/mil1ion/3bd0cd9b50ccc79b.gif
The 78/79 wiring diagram has a RED going ot the Tank selector switch.
A BLUE going to the Tank selector switch
Do you have Dual Fuel Tanks ?

HTH

Dennis


Dennis

 

I have a 77. It may have had dual tanks however it does not anymore, just one behind the axle. The bed is not original, so I dont know. The dash however is original and there is no selector switch on it, where would it be? The ALT light works and all the dash lights work, however the temp guage and the fuel guage do not work. It has an aftermarket temp guage, so thats no concern, however I would like to get the fuel guage working. If the vinyl circuit board was bad, would the dash lights and the non-analog guage still work?
Thanks
Aaron

 

Sounds like your CVR -constant voltage regulator - has given up the ghost.This is that little metal unit that snaps into the printed circuit board and is attached to the back of the cluster by one screw.With a test light you should have battery voltage at one terminal with key on and the other terminal should have a significant amount less,but your test light still should glow.Any parts house sell these.Ford gauges dont operate on 12 volts,the CVR's job is to lower the voltage to them.

 

what years did ford use the CVR to provide lower voltage to the gauges? I have a '70 in which neither the fuel guage nore and temp gauge work. Both gauges are powered by the same terminal which is not getting any voltage with the key on. I was just going to run a fused jumper from the ignition to this terminal. However if they opperate on a lower voltage this may not be possibel. Is there any other place that a CVR might be located other than on the instrument panal because the gauges are powered directly from the wiring harness.

 

With the key on ,test the plug end of your wtaer temp sending unit attached to the engine.
See if there is a pulse of power to it.
I once had a problem with my printed circuit on my 78.
I eventually removed it from the truck pulled off all the gauges and bulbs, then cleaned the printed circuit,re-assembled it and it worked as good as new.
If you don't have a fuel tank switch that explains the Red wire being loose.
It is normally located to the right side of the heater control panel.
The dash lights work independently from the gauges.

If I have a photo of the schematic,do you want me to send it to you?
Or do you already have one?

Dennis


Dennis

 

Dennis, if you have a schematic please send it to me.
aaron-weber@utulsa.edu
Thanks
Aaron

 

me too on the schematic!
only2human(No Email Addresses In Posts!)