GageMarzigliano

My light switch on my 93 d350 burnt up this morning in the dark..all I had was headlights..no running lights at all..I replaced the switch but I'd rather do something else so I don't have to worry about the switch burning my wiring up the next time it decides to go..so I was thinking a few toggle switches to run all the lights..if it can be done and look good I would like to do it..and I'm not worried about not being able to dim the cluster lights..if anyone has and ideas or input on doing this I would greatly appreciate it. If anyone has done this and has a drawn up diagram for the wiring connection that would be great too..thanks in advance!

peckens

Yes it can be done. I know there was a thread awhile back and someone did it successfully. I can't seem to find it though.

You would loose your dim function.

peckens

Found the pictures, not a write up though.
http://www.cumminsforum.com/forum/89...-today-53.html

torquefan

Even if you put your lights on toggles, you would be better off to run the heavy current through relays, so you wouldn't be any farther ahead than using your factory light switch to power the lights through relays.

j_martin

Like he^^ says...
Put a relay right under the light switch, bolted to the dash for the clearance lights. Put headlight relays in near the battery and wire directly to the lights. That's 3 more badly needed fuses in these trucks.

It's amazing how much brighter ordinary halogen lights are when you aren't powering them through 30 feet of 16 gauge wire and a weak switch.

Jim Lane

Suprisingly the Ground lead off the headlamp socket is only a 20-gauge wire.

Jim

GageMarzigliano

Peckens..i did not see any pictures in that link other thana few of some first gens, and everyone else.. I couldn't just wire the lights into toggles with fuseable links?

peckens

Here are links to a pic, but def. do the relay mod. There is a sticky in the DIY section.

flyboy129

One of my first mods to my gasser 85 was headlight relays. The stupid headlight switch still melted down later on. I put toggles on, then the fuse box melted. I rewired the entire %^&$ truck with 16 gauge being the smallest leads anywhere (old wiring was shot) and put in two-6 slot fuse centers (one always hot, one ignition). Still run toggles now.

j_martin

The big feature of the posted relay mods is to run new fused supplies to the head lights, tail lights, or heater fan, thus taking the load off the switches.

Heater fan power, for instance, goes through a fusible link, the ignition switch, a fuse, the heater control module, and the fan switch. With relays, only a signal current, approximately 0.1a goes through all that, and the full power goes only through the relay and heavier wiring installed.


Both the head light and tail/clearance lamp circuits are grossly under-served by the stock switch and wiring.

GageMarzigliano

So basicly i can put them on toggles, they just need to have these relays you speak of?

flyboy129

Yeah, I had separate fused headlight power. It was the marker light circuit that did the damage.

GageMarzigliano

Ok one more thing..why the relay upgrade? Since the power all comes from the fuse box already fused.. sorry I'm just not to savy when it come to indepth auto wireing. Thanks for all the responses.

j_martin

The wiring, and the headlight switch, are less than adequate in the long run. The switch contacts, and also the connector contacts on the switch, as well as connector contacts on fuses
1. deteriorate with age
2. increase voltage drop
3. generate heat
4. go to (1)
<end loop> Fire and failure

It's a snowball effect that ends in catastrophic failure of the switch and it's connectors.

1 fusible link supplies the whole mess, so the failure of one component usually won't break the so called fuse before wires burn off. Replacing the headlight switch with bat handle switches just transplants the problem.

When you install relays, you divide the current to high beam, low beam, and marker lamps into 3 separate circuits, each with it's own fuse. The 30 amp relays with self cleaning contacts easily handle the 5-10 amps in each circuit. The only current that goes through the old inadequate wiring and switches is the coil current for the relays, typically 0.1A. The only real wear on the switch is mechanical. Relays plug replace in seconds.

Bonus is that your lighting, especially head lamps, is brighter because much inadequate wiring has been bypassed.

Best location for relays is near the battery for the head light relays, and near the switch for the marker light relay.

Believe me, those of us that have done it are happy with the results, and kicking ourselves for not doing it sooner and avoiding the back breaking core of crimping in new connectors under the dash, and having to tear the dash apart to replace a headlight switch.

I've been around long enough to see this problem evolve through the years. In the 60's headlights were pretty wimpy and switches were made of real metal. In the 70's, headlights got more numerous (quads) and the switches got cheaper. I was driving a Ford high cube van when the dashboard caught fire because the head light switch failed. I had an extinguisher in the cab, quickly diagnosed the problem and killed the power and put the fire out. Was a long cold night getting everything home and off the freeway.
Then the "engineers" got the bright idea to put a thermal breaker in the switch. It eliminated most of the fires by failing the switch, but it didn't solve the problem. That's about where the first gen Dodge is.

Now we've gone full circle, and most new cars and trucks have relays, or even solid state relays.

The same scenario goes for the heater motor circuit, with the addition that a permanent magnet DC motor typically increases current draw with age, adding to the snowball effect.

I hope this helps your understanding.

mknittle

A good source for the parts.
http://www.delcity.net/