Headlight Switch

[jbgroby]

My brother and I figured out the pins on the new OEM headlight switch, took about an hour of testing and drawing. I hope this helps others and NONE of the pins are marked nor do the switches seem to come with any instructions.

you have two hot pins P-1 and P-2, we decided to make a short to P-2 so they would power the two pins next to it at the bottom.

[Clyde65]

This definitely should be a sticky or something where it is readily available to members!

[jbgroby]

Ok, here are a few quick pics of the jumper and the dual pin set up. As I cut the wires short I crimp, solder and heat shrink, I have to do so sitting in the cab. The blanket on my lap acts as a safety net for the hot solder as you can see. The wiring is going slow as I'm kind of anal when it comes to doing it correct, I don't want to have to do it twice. I learned a long time ago time ago from my Father-in-Law (since passed) think twice, measure twice, cut once!

The first pictures shows the dual male connector.
The second pic shows the jumper, the blue insulator is only temporary so I can measure the length of wire for the jumper.
The third pictures shows the new connector on the main hot lead for the switch, which will allow me a extra mail connector for the jumper.

[tincan1966]

Not to be a jerk, here, but I am assuming you didn't have the OEM plug in? Because normally there isn't much deciphering here, just plug the switch in and go, unless you are wanting the park lights on all the time with the tail lights. In that case you just jump the purple wire going to the park lights to the brown wire going to the tail lights.

I guess I am a little sketchy on what you are trying to "fix" or repair. All the wiring diagrams for these trucks labels every wire on the switch.

It's a nice write up, just don't understand the dilemma you were trying to solve.

[jbgroby]

I have a new wiring harness from E-Z with bare wires and the OEM headlight switch would not match up because the "running lights" do not stay on when your headlights are on for the 60-61 (or some later years). Also I have the full options package as follows

glove box light, cig lighter, hazard switch, spotlight, compass w/lgiht (control with main power)

Instrument lights, radio, dome (control off reostat)

The main issue is trying to have several wires grouped not enough male spades.

[tincan1966]

If I remember correctly, the glove box lamp, cig lighter, and accessories feed power from the fuse panel ACC circuits, originally, not the headlamp switch. Running all these off a single power feed to the headlamp switch and jumped to create an ACC circuit will overload that circuit and possibly shorten the life of the switch, too.

You can purchase replacement wire ends and reuse your old headlamp harness plug housing.

I'd recommend feeding power to your accessories from the fuse box with proper amperage fuses for the specific load requirements.

We've tried to use the EZ wire harnesses in our shop before(customer's purchased them) and were very unhappy with circuit selection/division and the overall quality of product/lack of useful instructions.

JMO.

[jtrichard]

the oem layout has 2 power feeds one for just the headlights the other is (fused) for tail and dash ( also feeds brake light switch) (headlights i believe are breaker-ed) so if you have a short in tail/brake lights it wont take out the head lights also... so when you have no dash lights but do have head lights you know you have no tail/brake lights

[tincan1966]

Originally Posted by jtrichard

the oem layout has 2 power feeds one for just the headlights the other is (fused) for tail and dash ( also feeds brake light switch) (headlights i believe are breaker-ed) so if you have a short in tail/brake lights it wont take out the head lights also... so when you have no dash lights but do have head lights you know you have no tail/brake lights

Incorrect.

The OEM harness provides one power source IN to switch. The orange OUTPUTS go from the H/L switch to the fuse panel, then to the dome lamp and the brake light switch.

Of coarse either opinion is negligible when using an aftermarket harness. Most of the time, if you follow the directions from a reputable harness manufacturer, there won't be any guesswork or jumping wires, etc to make everything work.

This is why Painless, American Autowire, Ron Francis and the like get beat up on about their prices- they solve all of the guesswork for you, include the proper connectors, and divide circuits and system up for the best performance.
You don't get that with a $169 harness kit.
When we are hired to wire a vehicle, we can't reply on cheap parts.

[shortstep66]

Originally Posted by jtrichard

the oem layout has 2 power feeds one for just the headlights the other is (fused) for tail and dash ( also feeds brake light switch) (headlights i believe are breaker-ed) so if you have a short in tail/brake lights it wont take out the head lights also... so when you have no dash lights but do have head lights you know you have no tail/brake lights

I have this problem with my 1990 Silverado. Bad connections in the switch on the dash causes my running lights and tag lights not to come on if the instrument panel isn't lit up, but the headlights always work fine. Some wiggling of the wires generally fix the problem for a while. It's good to know I'll have that 'tell' in my C-10 when I get that far with the restoration. This is such a good thread.

[jtrichard]

my bad i was thinking it went from fuse to switch i stand corrected... i knew that there was a fuse for just the tail/brake/dash separate from the head lights

[ray_mcavoy]

Originally Posted by jtrichard

my bad i was thinking it went from fuse to switch i stand corrected... i knew that there was a fuse for just the tail/brake/dash separate from the head lights

Actually, you were correct with your initial description. I disagree with what tincan1966 said about the orange wire being an output from the headlight switch. The orange wire is a fused input to the H/L switch that is live all the time (not switched on/off via the H/L switch like an output would be).

If you look at the factory wiring diagrams, the main power feed wire (usually red) has a factory splice that branches off to feed the headlight switch, ignition switch, and one side of the "TAIL STOP" fuse (among others). The other side of the "TAIL STOP" fuse is connected to the orange wire that feeds power to another factory splice that brances off to feed the brake light switch, dome light, and headlight switch.

As you said earlier, the two inputs to the H/L switch (red unfused, and orange fused) allow the circuits to be separated so a short in the tail/brake lights won't take out the headlights or vice versa. And yes, there is usually a circuit breaker built into the H/L switch to protect the headlight circuit since the red feed wire is unfused.

[par4tom]

Ray,
Is the unfused portion of the red wire that initially feeds the h/l switch and ignition fused at any point prior to feeding these switches?

[ray_mcavoy]

Originally Posted by par4tom

Ray,
Is the unfused portion of the red wire that initially feeds the h/l switch and ignition fused at any point prior to feeding these switches?

No, the factory wiring does not have any fuses (or other protection) in that red wire prior to it feeding the switches.

And yes, that is definitely a safety concern. Both with factory wiring and with most reproduction OE type wiring harnesses.

Starting in 1967, GM added fusible links in the underhood wiring that protect that main feed wire. Adding fusible links to the earlier year wiring is definitely a good idea.

[jtrichard]

Originally Posted by ray_mcavoy

Actually, you were correct with your initial description. I disagree with what tincan1966 said about the orange wire being an output from the headlight switch. The orange wire is a fused input to the H/L switch that is live all the time (not switched on/off via the H/L switch like an output would be).

If you look at the factory wiring diagrams, the main power feed wire (usually red) has a factory splice that branches off to feed the headlight switch, ignition switch, and one side of the "TAIL STOP" fuse (among others). The other side of the "TAIL STOP" fuse is connected to the orange wire that feeds power to another factory splice that brances off to feed the brake light switch, dome light, and headlight switch.

As you said earlier, the two inputs to the H/L switch (red unfused, and orange fused) allow the circuits to be separated so a short in the tail/brake lights won't take out the headlights or vice versa. And yes, there is usually a circuit breaker built into the H/L switch to protect the headlight circuit since the red feed wire is unfused.

its been years since i have been under the dash but i though that the way it was and i thought there was a breaker in the light switch that just runs the head lights .....I havent driven the 63 in years but i do remember that when there was no dash lights that there was no tail/brakes either (dam trailer wiring shorted again)

[par4tom]

One last question on the unfused wire for Ray:

Any idea how much maximum amperage that red wire would draw, lights, heater fan, headlights, taillights, radio, wiper, etc all running? 60 amps?

[ray_mcavoy]

Originally Posted by par4tom

One last question on the unfused wire for Ray:

Any idea how much maximum amperage that red wire would draw, lights, heater fan, headlights, taillights, radio, wiper, etc all running? 60 amps?

Just a rough calculation here, but the tail lights, all the dash lights, etc. probably draw a combined total of around 3 to 4 amps. Stock 6012 sealed beam headlights are 55W on high beam so that's another 8 amps or so for both. The heater fan motor shouldn't be any more than 7 or 8 amps (I'd have to measure one to be certain). The wiper motor should be under 12 amps (again, I'd have to measure one for a more exact calculation). A stock radio doesn't draw very much power ... maybe an amp or two at the most. And then you have the engine's ignition system, gauges, and such being powered off that wire as well ... so figure in another 5 to 6 amps.

Adding that all up, I get 40 amps. Again, that's just a rough calculation but should be in the ballpark for mostly stock electrical loads. And as mentioned, the headlight relays will reduce the load on both the H/L switch and that main feed wire.

The important thing is to make sure that main feed wire is protected according to it's size. Like imjeff said, use a fusible link two sizes smaller (4 AWG numbers higher) than the wire. I believe this main feed wire is 12ga on most of these trucks so a 16ga fusible link would be the size to use.

The circuit breaker you added near the battery is a good idea. However, it would be possible to overload and damage a 12ga wire without tripping a 100A breaker. So unless you've also upgraded that main feed wire to something heavier than stock, I'd recommend protecting it with a smaller breaker or fusible link.

Originally Posted by tincan1966

Since we're being so critical of descriptions, I never said the orange wires were a "switched" output.
BUT like I said, I'm ok with you disagreeing, I never claimed to be an expert and darn sure don't want to ruffle anyone's painties over it. I just read the diagrams I have differently and know how mine and all the ones I've wired in the past worked. That's all.

I guess we're just looking at the diagrams & wiring from a different point of view in terms of what we're considering inputs vs. outputs

[tincan1966]

Originally Posted by ray_mcavoy

Actually, you were correct with your initial description. I disagree with what tincan1966 said about the orange wire being an output from the headlight switch. The orange wire is a fused input to the H/L switch that is live all the time (not switched on/off via the H/L switch like an output would be).

If you look at the factory wiring diagrams, the main power feed wire (usually red) has a factory splice that branches off to feed the headlight switch, ignition switch, and one side of the "TAIL STOP" fuse (among others). The other side of the "TAIL STOP" fuse is connected to the orange wire that feeds power to another factory splice that brances off to feed the brake light switch, dome light, and headlight switch.

As you said earlier, the two inputs to the H/L switch (red unfused, and orange fused) allow the circuits to be separated so a short in the tail/brake lights won't take out the headlights or vice versa. And yes, there is usually a circuit breaker built into the H/L switch to protect the headlight circuit since the red feed wire is unfused.

Since we're being so critical of descriptions, I never said the orange wires were a "switched" output.
BUT like I said, I'm ok with you disagreeing, I never claimed to be an expert and darn sure don't want to ruffle anyone's painties over it. I just read the diagrams I have differently and know how mine and all the ones I've wired in the past worked. That's all.

[tincan1966]

All I know is how I read the diagram and how mine is wired(all original dash harness) and my 25+ years automotive wiring experience.

BUT , hey, I can be wrong and you can wire it however you want to.

I personally just wouldn't want that many circuits on a single feed. That was my original hint of advise I was trying to give.

[imjeff]

You can greatly decrease the load on the headlight switch by installing relays for your headlights. This will increase its life and decrease your chances of overloading the wire. Then just add a fusible link two sizes smaller than the wire.

[par4tom]

Jeff,
I did install headlight relays. I also installed a 100 amp resettable circuit breaker about 18" from the battery for the vehicle electronics. Left one small wire "hot" from the battery so it didn't erase the memory from the aftermarket radio.

I was just wondering if the 100 amp breaker was going to be enough.

I'm an old-school car audio guy, and we always fuse at the battery for a large audio system and then again at the amps. My audio system is on a separate 100 amp breaker.

[imjeff]

Couldn't have said it better Ray! It's funny that we have more accessories to put in these trucks, but with LEDs and some relays we have greatly decreased current demands. Unless, of course, you have a gigantic stereo and heated seats!

[61K10]

there are different way's to rewire. I took my harness completely apart, cut out all the soldered connections and added a fuse box (had it from another project)
of course not stock but everything is on its own fuse.

[par4tom]

That's a good idea...my thoughts initially were that if there was to be a short in the factory wire, the breaker would trip. (Shorts can generate 100's of amps of current in a hurry when direct to ground and until the wire burns through).

I may get a 60 amp breaker just in case...I liked your calculations. Thank you.
T

[jtrichard]

tom you would be better off with about 30 amp max remember just like in your house wiring not everything is on at the same time the main power is 12ga. and only good to 40amp MAX at 10' and that is only for short periods .......look at this for your wire and fuse size http://www.offroaders.com/tech/12-vo...gauge-amps.htm

[ray_mcavoy]

Originally Posted by jtrichard

tom you would be better off with about 30 amp max remember just like in your house wiring not everything is on at the same time the main power is 12ga. and only good to 40amp MAX at 10' and that is only for short periods .......look at this for your wire and fuse size http://www.offroaders.com/tech/12-vo...gauge-amps.htm

I agree with your 30 amp recommendation. And I'm glad you brought that up about not everything being on at the same time. The calculation I posted earlier was done with everything on at once as a "worst case" / "maxium load" scenario. And if the 40A that I added up is close, it goes to show that the stock 12ga wire would be right at it's max current capacity as you pointed out for short periods of time.

Originally Posted by par4tom

...my thoughts initially were that if there was to be a short in the factory wire, the breaker would trip. (Shorts can generate 100's of amps of current in a hurry when direct to ground and until the wire burns through).

You're on the right track with those thoughts. Yes, a short to ground in the factory feed wire would most likely pass enough current to quickly trip a 100A breaker before it had time to melt the 12ga wire. It's just in the event of an overload that's too much current for the 12ga wire (but not enough to trip the breaker) that you'd have a problem.