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Hi fellas,
I'm new to TDR and a new first-time Diesel owner. I finally bought the '93 W250 that I've been wanting ever since I was 14 years old. It needs some cleaning up and rewiring, but it's in great shape and I really like it.
Here's the deal: The headlights were intermittently flickering off and on. So, I wired in relays up next to the lights. I went a little overboard with 4 relays (one for each beam on each headlight). Then I bought a new headlight switch and changed it out. I tried the new relays and switch. All worked fine except, the new switch was getting just as hot as the old one with the switch on in all positions. So, I thought maybe the parking lights were overworking the switch (previous owner had added high-5 cab lights and plenty of LEDs to the flat-bed). So, I added a fifth relay between the switch and the circuit that powers all the running/parking lights.
Result: No help. Everything works fine and burns bright(er), but the little rotating part of the switch (that controls the dash brightness) gets blazing hot and even lets off a little smoke after a while.
Is the switch just going to get hot no matter what? Since the big circuits coming off the switch are now on relays, would installing a resistor between the battery and the switch be a solution/possibility?
I'm fairly ignorant when it comes to electrical stuff and could use some sage advice.

Thanks in advance,
Verbum Domini Manet in Aeternum
 
Is the dimmer for the dash lights in the headlight switch? If so, turn the dash lights down all the way and see if that stops it from getting hot. I know the later year models have a roller type dimmer apart from the head light switch. The dimmer is just a resistor which creates heat. Could be a short in the dash lights. bg
 
The dimmer is part of the switch, and that is what gets hot. After doing some more poking around here, the general consensus seems to be that turning the dash lights all the way up reduces the heat from resistance, but I will experiment with both extremes and see if there is any difference. I'm really curious as to whether adding a resistor before the switch would help or make any difference. As I said, I'm rather ignorant about electricity and I don't want to cause a fire.

Verbum Domini Manet in Aeternum
 
Yes, all the way up would reduce the resistance (I had it bassackwards). A resistor in the 12v line will only cause a voltage loss depending on what value the resistor is. Don't know if there is a LED bulb that could be used in the dash/instrument lights but if so they should require less amperage to run. bg
 
I burned up two factory switches then I got creative and did this.
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That's bad ***! I'm kind of a junkie, when it comes to switches and knobs. I have visions of turning my dash into the cockpit from the movie Airplane! I'd like to know what each of those switches operate.
By the way, I tried running the lights with the rheostat at both extremes and different positions today, and sure enough, all the way up is ice cold; Any variation gets it cooking within seconds.
 
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Starting from left to right the switches run the marker lights, head lights, dash lights, fog lights, trailer lights, and finally dome lights.
 
Try Super Bright LEDS. I am running them in all my exterior lights and dash lights. I converted both my front side markers and front directional lights to LED. I had to modify both to get the results that are legal. You you will need to provide resistence so that your directional lights will flash bright enough to be seen at night. I solved this problem by running conventional lights in only my brake lights. A no load flasher would not solve the low light output at night.I found directional and front side markers at Six States OTR truck suppliers. I used the original front directional housings and cut out the back portion and used silicone to keep the light pack in place.

Bob
 
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