Help! Headlight switch getting hot!

[DuallyGuy]

I had a melted headlight switch connector and a old beat up headlight switch. So I replaced them both including new wires. I turned on the headlights and I could still feel the orange wire was still getting hot. As you can see in the photo, the orange wire splits into two orange wires. I've tried tracing them to see where they go but it disappears behind the dashboard not to mention it's completely wrapped. If I don't need these wires, then I dont mind cutting them and eliminating the hot orange wire altogether. Can anyone tell me what these wires power up? I'm trying to find out before I cut them. One orange wires goes to a harness to the left and the other to a harness which goes to the right. I give up. As you can see I pulled out my cluster just to search.

 

[RetroC10Sport]

Looks like something got tied in to where it shouldn't be.

PM'd the factory wiring diagrams for you to look over.

 

[DuallyGuy]

Thanks for the diagrams. I'm reviewing it right now. Hopefully I can solve this mystery.

 

[chengny]

Don't cut them - if you do you will have no parking/tail lights or courtesy lighting. They are correct. But, the way that the wires are layed out is kind of deceiving.

It appears that one orange wire comes out of the lighting switch and branches off in two directions. That is not the flow.

What you are actually seeing is one fused hot wire coming in from the T/L CTSY fuse slot - but before it connects to the light switch it splits off. That branch supplies power to the courtesty lighting circuit.

The fused feed then continues on to the switch. When the handle is pulled halfway (or all the way) out, power from the orange wire is directed to the parking lights.

The courtesy light circuit is hot all the time on that orange wire side - opening a door (or twisting the dimmer knob all the way over) closes a switch that creates a path to ground. The CTSY lamps illuminate.

The parking/tail/courtesy lights are the only fused lamps that pass through the switch. The headlights are supplied with unfused power straight from the battery - well, not exactly unfused - the H/L's are protected by a fusible link.

Marked up wiring diagrams showing the layout of the circuit - up to the switch:

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[chengny]

As for the heat issue; since the orange wires are fused they are probably not generating the source of the heat. If there was any fault in the wiring, you would be blowing that T/L CTSY fuse all the time.

Does the orange wire get hot even when the H/L switch is pushed all the way in?

Or does it only heat up when the switch is pulled out (to either position)?

Where exactly does the orange wire get the hottest when this happens?

You have to ask yourself - why did the original switch fail and melt the connector.

 

[MrMarty51]

Sometimes a corroded connection at the switch will create excessive heat and cause them plastic connection housings to melt, I`ve seen this more than once.

 

[DuallyGuy]

Thank you for replying and sorry for the delay. The orange wire gets hot when the headlight switch is pulled out either halfway (parking lights) or completely (Headlights). It does not get hot if the switch is pushed all the way in (off). Before I replaced the headlight switch and the terminal connector, I could feel it getting hot right at the terminal. So I replaced them both. But now that everything is snug, I can still feel the orange wire warming up right before it Y's out. Also, I noticed when I throw my High beams on, my passenger Low Beam will shut off (4 headlamp truck). Does that have anything to do with this issue? Or is that a seperate issue? Thanks again for the info.

 

[chengny]

I can still feel the orange wire warming up right before it Y's out

Suspect a loose (or missed) crimp at the solderless connector as shown below. Due to increased resistance, loose electrical connections will heat up when current is flowing through them.

Since this has been going on for a while, it might be wise to start fresh. Rather than just re-crimping, suggest cropping out the used connector.

Strip the wires and make a new splice. Either crimp in another solderless connector or make a proper joint (with solder and heat shrink tubing).

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[chengny]

Also, I noticed when I throw my High beams on, my passenger Low Beam will shut off (4 headlamp truck).

If both the low beams work (when only lows are selected), the lamp is okay.

Both lows are fed off the same lead (tan wire, splits over to the RH lamp at the LH socket). That same tan lead supplies power to the low beams regardless of whether low or highs are selected.

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So, if only the only problem is that the RH low fails to illuminate (actually, it goes out) when highs are selected you almost certainly have a grounding issue.


Pull, clean and re-tighten the common lighting grounds on the radiator support frame.

 

[DuallyGuy]

Thank you for the great input. I will definitely follow your advice. I'm a little skeptical about the loose crimp because I used both of my mitts and proceeded to crimp the life out of that wire. Perhaps I pinched it off? Doesn't look like it though. I can def solder it. I hope that's solves the problem. However, when I was feeling the wire for heat, the entire wire seemed to warm up before the Y meaning that it may have been heating up at the terminal as well. But those terminals are all brand new and as well as the wires which run up to the crimps. I will def clean my grounded connections too. Thanks a lot. I'll update as soon as I find out if I fixed it or not. Thanks again.

 

[foamypirate]

So, here's a question. Just how hot, is hot? The headlight switch and some of th e associated wiring always got hot (but not HOT) in both of my squares. The headlights pull a lot of current, and will create some heat in the switch/wiring. Perhaps you can try qualifying just how hot yours is getting. Is it, "Meh, it's a little toasty" or "HOLY CRAP I COULD SEAR A STEAK? IN TWO SECONDS FLAT?!"

 

[DuallyGuy]

I would say a lil toasty, actually. Def not as hot as it got before I replaced it. But I just assumed its because the wiring and insulation is all new and the connector was melted so much the terminal was exposed on the orange wire and so I was able to touch it with my finger and I was like holy crap that's hot. So I'm not sure if it's really less hot or if I'm just not able to feel it as accurately as I did last time.

 

[chengny]

Just a suggestion;

When you break the "Y" connection open, do a check on the courtesy light branch by leaving it out.

Temporarily connect only the fused supply to the switch.

If I had to guess, I'd say the courtesy lighting branch is the one on the right - the one that heads inboard.

Then fire up the parking lights and see if the wire gets hot.

If not, try re-making the "Y" connection as original and feel for heat again. If it then gets hot, it would indicate a problem in the CTSY light branch.

 

[77 K20]

To kinda go along with foamypirate's thinking- the headlight switch does normally get warm/borderline hot. Sounds like yours is a bit more than that....

but have you ever considered a heavy duty headlight harness? (once you check your existing wiring anyway)

I bought one last year from LMC. Right now all the electricity has to go from the battery thru your headlight switch and then to the headlights. The new harness then has the power go from your battery directly to the headlights. My switch is much cooler now- and I'm running 100 watt H4 high beams.

The new harness needs to be wired to the + of the battery and then to a nice ground. The OEM connectors that plug into the headlights are disconnected. One of them (*I have a single headlight system, dual would be similar) then gets plugged into the new harness. This provides signals for low beam and high beam to turn on a relay that sends power directly from the battery. Even if I had the stock headlights they would be brighter as there is a voltage drop thru the old OEM wiring and then thru all the connectors and the headlight switch.

Something you might want to consider anyway. $30 at LMC or I've heard there are other places also.
http://www.lmctruck.com/icatalog/cc/full.aspx?Page=72


P.S. Your headlights now are stock wattage aren't they?

 

[DuallyGuy]

That sounds like an awesome idea actually. As far as I know they're normal stock wattage sylvania headlights. One thing I failed to mention not knowing if it really mattered or not is that I have a Lance camper. Will that tend to draw more through the headlight switch? Sidenote; I have unplugged the campers electrical just to make sure that it wasn't the reason for the hot wire. The wire remained hot. But thanks for the tip. I'm definitely gonna peep that out.