69 Charger fuse block orange wire

[Monkeymaster]

Hello,
My 69 charger has a fuel gauge, sending unit issue.
I wanted to verify it had power to the gauge, I took my test light to the fuse block in glove compartment,
and I had power to all the fuses except the farthest one on the right side.
It is the "3 amp" fuse holder with an orange wire at the top of fuse holder, with "inst"typed on block, and then has a brown wire at the bottom, with "LPS" or maybe "LP5" typed on block.
I have a cd service manual, but can not find a wiring diagram with these combonations, at least my eyes do not see it.
Where do these 2 wires come from, or go to, and what are there purpose ?
I want to correct this before I trouble shoot my gauge issue, which this may be it, because everything else electrically is working, other than my fuel gauge.Thanks in advance !

 

[Beekeeper]

The orange wire is the feed to all the instrument lights and the tan wire is the feed to the fuse it comes from the panel dimmer. This fuse will have voltage only when the park/headlight switch is on. To help with the fuel gauge issue we need more info does the temp and oil pressure gauges work?

 

[Monkeymaster]

Thanks,
That makes sense, because I did not have the instrument lights on, and or dialed up.
I will do that test tommorrow night.
All other gauges are working.
I installed a new fuel sending unit last year, bought from Jegs, bench tested with Fluke, worked fine before installation.
I gounded my sending unit wire out, fuel gauge did not move.
I have a grounding wire from tank flange to frame, and have continuity from tank to frame. I took an ohm reading with my Fluke, it reads 43 ohms, and I have around 5 to 6 gallons of 91 in the tank.
Thanks

​

 

[Beekeeper]

If the other gauges are working the gauge feed is good they all use the same feed and go through the voltage regulator in the instrument circuit board.
Behind the drivers kick panel is a connector for the rear harness that has the fuel sending unit circuit
in it. Remove the kick panel and disconnect the connector and check continuity from the connector back to the sending unit it will be the dark blue wire in the harness. You can then ground the dark blue
Going up to dash at the kick panel to see if you get deflection in the gauge. Do this and report back the results

 

[Monkeymaster]

Thanks,
orange and tan as you stated, had to roll my dash lights up, reads fine.
Took kick panel off, took apart connector, good continuity back to the sending unit, grounded blue wire up to gauge to steering column bolt, no movement of fuel gauge.
I assume it is toast ?
Thanks again

 

[Beekeeper]

next thing would be to check continuity from the connector up to the fuel gauge. This will require removal of the instrument cluster. Also the speed nuts that connect the gauge to the board could be loose or need the connection cleaned. If this is all good it would be safe to say the gauge is toast. If you find that it is let me know I have one I have restored that's available.

 

[Monkeymaster]

Thanks,
I will check this weekend and get back to this post.
Thanks again

 

[Monkeymaster]

ok
Got up in by gauges and in doing so, the gauge moved, so I disconnected the battery and unhooked the wires, cleaned them, and dabbed some anti corrosion electrical "no lox" on them, and all is good.
I guess 48 years is long enough to cause a little corrosion or carbon build up.
Thanks for all the help Beekeeper.

 

[Beekeeper]

Thanks that's great glad you got it fixed and thanks for reporting back with what you found as it might help someone later on.