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Pulled out the stereo to check why it was turning on/off intermitently - that part is easy enough (thought.... the key'd power is going into a plug I'm confused/concerned about)
Edit: 1974 F250
Looking inside/under the dash behind things, I'm finding two plugs that don't plug into anything - green wire with elbow, and red/blue wire into straight connector - curious if anyone has ideas what these would go to? (I know my fuel gauge doesn't work, any chance one of these would fix that or something else?)
And the green plug that's obviously supposed to be plugged into something - it's running the key'd power for the steroe - was this part of the original stereo, or did this go to something else?
I believe the single green wire on the right is for the 12v/cigarette lighter socket that I see missing on your dash. The two wire green connector was for the original radio
X2 on the green for the lighter. The blue/red is a dash light power. It could have gone to anything with a light, like the original radio. The rest looks like spaghetti fired out of a bazooka.
X3 the green 2 wire plug is for the OEM radio. FYI THEY ARE BOTH HOT wires. So not your norm one hot, one ground. The OEM radio grounds via the mount bracket. One is hot always for radio station memory and one is keyed hot for the radio itself.
"Improper radio installation, the common mistake is to use the blue-with-red-stripe wire as a ground, since it shares a connector with the yellow switched-12V+ wire, and that will blow that fuse the first time you turn on the lights and hit the brake. That blue-with-red-stripe wire is for the dial light in the original factory radio, so if it gets grounded, it will pop that fuse."
X3 the single green with the 90* is for the OEM cig lighter. And it goes over to a 3 port (always hot) bullet connector plug behind and or just to the left of the glove box. The glove box light also gets its power from that 3 port always hot plug.
Usually the wire it Y'ed from just one power port to the glove box light and then Y'ed to the cig lighter. So no cig lighter no need for it, take it out and just plug in the glove box light single bullet connector.
That other spaghetti pile looks to have none OEM speaker wire connected so door or behind the seat aftermarket speaker wiring.
As always, you all are amazing! Though I'm bummed you didn't solve my fuel gauge with this ;-)
Finishing up re-wiring the stereo now! Love that the hot positive wire coming direct from the battery was done with speaker wire. Now replaced with new 14gauge
As always, you all are amazing! Though I'm bummed you didn't solve my fuel gauge with this ;-)
Finishing up re-wiring the stereo now! Love that the hot positive wire coming direct from the battery was done with speaker wire. Now replaced with new 14gauge
Don't forget to add an inline fuse on that new wire you added from the battery. I made the mistake on the '79 I owned years ago, thinking, well there is a fuse on the back of the new head unit I will be fine. I was lucky I didn't burn my truck down, I could smell something burning that I knew was electrical and was melting insulation, stopped the truck, popped the hood and the wire I ran into the cab was melting all the insulation off the wire, ended up burning my hand but I yanked on the wire real hard to disconnect it from the battery and stop the current flow. The fuse in the head unit never popped, and due to melted insulation the wire shorted to ground on the inner fender well and along the firewall so the fuse wouldn't have helped at that point anyway.
Lesson learned! Any wire I hook directly to the battery now gets a fuse within 12 inches of the battery or so. On my current '79 I added an extra fuse panel in the engine bay since I needed a 12v for the head unit and I added some headlight relays when I installed the new H4 style LED bulbs.
More radio power talk. "The OEM radio was powered by a GREEN 2-terminal pigtail. YELLOW with a BLACK stripe is switched power, BLUE with RED stripe is dash illumination. Do not mistake the BLUE with RED stripe wire for ground. The OEM radio grounded through its mounting chassis. The speakers were connected over a separate pigtail.
Looked behind the glove box and find a connection the goes off the green and yellow. GREEN with YELLOW stripe wiring is hot-at-all-times power for the courtesy lamp circuit. Use that. There is a black 3-connector pigtail behind the glove box (which also goes on to power the cigarette lighter).
It's not the stock radio wire because the stock radio didn't need hot-at-all-times power (EXCEPT the factory digital AM radio for clock memory)."
I am pretty sure that neither of the 2 random plugs behind the dash have any thing to do with the fuel gauge. Fuel gauge trouble shooting.
" 1. make sure you have one wire that is a ground back at the sending unit, if that did not fit it. 2. disconnect the elec connector (there is a 90* 2 wire push on connector) that goes to the fuel sending unit at the tank. You need to pop the plug off for the test. Yes you can barely get up in there with your head and see the plug. While looking at it, or just feeling for it, pop it off. Now VERY CAREFULLY if you can not get it with your hand, use a long screwdriver to pry it off. AND I MEAN VERY CAREFULLY. It is only pushed on like a 1/8". Again this is only if you can’t get it with your hands.
Now you need a helper....to turn the ignition to the "run" position and you use a jumper to quick ground out each bullet plug hole (one at a time, at the plug) you just removed from the tank sending unit. And have your helper watch the fuel gauge. If the gauge swings all the way to full, either the sending unit itself is bad or it has a bad ground. If the gauge stays on empty then either the gauge is bad or there is a wiring problem."
Lesson learned! Any wire I hook directly to the battery now gets a fuse within 12 inches of the battery or so. On my current '79 I added an extra fuse panel in the engine bay since I needed a 12v for the head unit and I added some headlight relays when I installed the new H4 style LED bulbs.
For a head unit I would think 10-15 range but might be as high as 25 or 30 depending on the internal amp it has. The owner's guide for the head unit might provide guidance or look at the fuse installed in the back, for most aftermarket stereos, and match that.
