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Fuse panel conundrum

Mach1 Driver

Well-Known Member
This is a good question for Midlife.
I have a FORD (Helm) manual with 37 pages of electrical drawings. It shows a fuse panel with an accessory post going to a 20 amp fuse #2. This supposedly feeds one or more of the following:
1. Seat belt warning
2. Swing tilt column
3. Door ajar
4. Low fuel
5. Power window
6. Speed control.
I'm the original owner and it is a completely stock 69 Mach1. It has a wire on the accessory post and a #2 fuse, BUT NONE of the above. So what the heck does this operate? Nothing else is shown in the diagrams.
Thanks for the help
 
Well what came with your car? Seat belt warning is the usual device that runs off this accessory post that I have seen. It's even possible that it came with your car and wasn't used for anything, but that seems unlikely to me. Do you have a Marti Report? That'll tell the story...
 
Mid, seat belt warning is item #1, and no it doesn't have it. I've read that is a separate light on the dash somewhere near the wiper switch? I never felt the need for a Marti Report, because I'm the original owner.
However, in the Temp/Fuel cluster there is a Brake System light that works on the left side, but I don't think the light on the right side has ever worked. What is that?
 
Could it possibly be the parking brake? I'd have to look where that's supposed to go.
 
I don't think so, its never had a light. Well dang I'm gonna have to pop the fuse an see what dies :eek:
Where this is all leading eventually is a listing off all the loads in the car. Why... because inquiring minds want to know. I will be upgrading with some items that may require a new alternator. Do you happen to know if this information is available somewhere? I need the amp draw for things like the A/C blower motor, wiper motor, wiper washer pump, etc.
I will probably need to take a reading through the various circuits with a ammeter.
 
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OK, the brake light in the fuel/temp cluster is your master cylinder brake warning light. There's another lamp socket below that (not to the right) but that is for an optional seat belt reminder lamp.

Based upon existing circuitry and fuses, the blower motors take less than 20 amps; parts of wiper/washer assembly takes less than 14 amps; other parts powered directly without fuse.
Let's do this another way...go by fuse.
ACC fuse: radio, backup lights, wiper/washer portion, turn signal flasher have 14 amp fuse.
ACC fuse: blower motor, 20 amps
ACC buss bar (#2?): 20 amps
Dash lamps: 4 amps
Battery fuse: e-flasher 30 amps
Battery fuse: courtesy lights, cigarette lighter: 20 amps

Everything else is run directly from either battery (unfused), ACC (unfused), or headlight switch (internal circuit breakers - 15, 18 amps).
 
In my 69 there is no light below the master cylinder light, but there is a red square on the opposite side of the temp and fuel gauges in that cluster, and it never lights. When I take the dash apart I'll have to check that out.
Thanks for the info, I'll run the actual loads and let everyone know what the current draw is for every item in my car. Someone may find the information of value. Things like motors can have 5x the inrush at start-up, and the fuses are sized appropriately. I noted that none of them are slow-blow so they just kicked the amperage of the fuse up by some amount to compensate.
I find it interesting that more of these old cars haven't shorted and gone up in smoke, since many of the circuits come directly from the battery without circuit protection. My car has 6 fuses and the two breakers in the headlight switch and I think that's it! Are there any fusible links? I didn't see any on the diagrams.
 
I'll predict that the total actual currents you find are about half of what the fuse is rated for. As for fusible links, they began in earnest in 1970, but some earlier power convertible top systems had fusible links near the battery/starter solenoid area.
 
Mid, I could use your help again: the diagrams show a resistor (probably a resistor wire) wire #30 violet that feeds the constant voltage regulator via the PCB for the gauges. Is this a wire, and do you know the resistance?
 
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