fuse block mods

[70MTroadster]

I got a chance to take out the Roadster for a fairly long run. Turned on the lights, heater, hazards, brights, blah, blah and no heating of the Park/Tail fuse Could it really have been that simple? Just that the 33 year old fuse holder blades were that dirty? Oh well, they are nice and shiny now and evidently that was all it was......until the next time anyway.

Continuing to be baffled and confused in Montana

scott

[spl310]

Once, on a rare occasion back in College when I actually had a date, we went out in my Roadster. It as dark and as we were driving all of the lighting died. (sure of the headlights, not sure about the taillights - hard to see them while driving! ) We pulled into a gas station and I proceded to check all of the fuses. None were blown. I was perplexed and proceeded to play with the fuses. Finally the lights flickered. I pulled out my trust pocket knife and scraped the clips. Lo and behold, a booming voice (inside my head) said "Let there be light! but you are SOL about this date) It was autumn, and the date did not care to be sitting in a dark sportscar while some clown (me) does a makeshift repair. So, I drove her home.

Anyway, yes, the buildup of crud can cause that problem. I also learned that the car had original fuses in most of the slots! fun stuff these cars.

Oh, I was not that disappointed about the date, so don't cry for me.

[Dave]

OK guys, time for me to be an engineering geek! Sorry...

Anyone familiar with Ohm's Law? The long and the short of it is: Voltage / resistance = amperage. Or, V/R=I. You can swap that around however you like. In the case of our dirty roadster fuse block, we have some added resistance. Let's put some numbers into the equation. Voltage stays the same at 12V. If we assume a resistance of 1 ohm in the circuit, we have this: 12Volts/1 ohm = 12 Amps. The consumer in the circuit (the lights in this case) can draw 12 Amps.

Now, let's get a nasty dirty fuse block. Our circuit now has a resistance of 4 ohms. Plug in the numbers and you get: 12V/4 ohms = 3 amps. The total power our bulbs can pull is only 3 amps. That's why they are dim. Resistance goes up, current goes down and the lights suffer.

So if the resistor (in this case a bad fuse block with lots of corrosion) is preventing the bulbs from drawing enough current, where is all that energy going? It goes to heat. The fact that the fuse heated up is a dead giveaway that the problem is in the fuse block. Had the excessive resistance been in a connector with corroded terminals, the connector would have heated up, not the fuse.

Hopes this helps.

[S Allen]

Cool! Glad to hear it was an easy fix and a little cleaning did the trick. Dirty connections can raise havoc in an electrical system.
Dave, thanks for the refresher on Ohm's Law.

Steve

[Minh]

Who was that kid in science class back in high school that said, "I am never gonna use this stuff?"

I guess he never figured on owning a Roadster.