Melted my new headlight switch
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It would not be a 'short' on a ground wire. If that happened and the lights were already ON, nothing would change...as that system goes to ground, anyway. The problem would have to be in a power 'feed' or 'transfer' circuit that is BEFORE the item being powered for it to draw heavy current.
Also, I would do as much diagnostic work as possible without pulling the dash. You may locate the problem and find that you don't need to pull it. So, do what you can to find the circuit having the short, FIRST.
Also, I would do as much diagnostic work as possible without pulling the dash. You may locate the problem and find that you don't need to pull it. So, do what you can to find the circuit having the short, FIRST.
Thread Starter
Racer
Joined: Oct 2011
Posts: 294
Likes: 0
From: Easton pennsylvania
Thanks for all the comments. I hope I can find it. But with the dash area being as tight as it is, I dont see how...
What about the door switches? I know my passenger door switch is touchy. Some times it doesnt work, but the slightest touch and it works. I bought two new ones, but I cant figure out how they are wired in.. Well, atleast not obviously anyway..
Ernie, I will send it out first thing Thursday. Shoot me a PM or email when you get it and take a look at it. I will obviously need a new one in the end.
What about the door switches? I know my passenger door switch is touchy. Some times it doesnt work, but the slightest touch and it works. I bought two new ones, but I cant figure out how they are wired in.. Well, atleast not obviously anyway..
Ernie, I will send it out first thing Thursday. Shoot me a PM or email when you get it and take a look at it. I will obviously need a new one in the end.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
It would not be a 'short' on a ground wire. If that happened and the lights were already ON, nothing would change...as that system goes to ground, anyway. The problem would have to be in a power 'feed' or 'transfer' circuit that is BEFORE the item being powered for it to draw heavy current.
Also, I would do as much diagnostic work as possible without pulling the dash. You may locate the problem and find that you don't need to pull it. So, do what you can to find the circuit having the short, FIRST.
Also, I would do as much diagnostic work as possible without pulling the dash. You may locate the problem and find that you don't need to pull it. So, do what you can to find the circuit having the short, FIRST.
I'm looking at the rheostat and thinking something had to get pretty hot for it to heat up enough to melt the plastic.
Since the courtesy lamps are on a separate wire, to me the logic would be power coming in on the ground (white wire). It wouldn't affect any of the other circuits since the tail lamps and headlamps all have other grounds... I think I'd better pull a schematic vs. shooting from the hip.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Xterrable,did you have any trouble getting the HL ****/rod back in the switch ?
When you removed the ****/rod did you notice any burn marks on the rod ?
It is possible for the rod not to seat properly in the inner contact slide,this forces the slide beyond where it is supposed to be and might cross the contacts internally making the rod hot. Just thinking out loud. Here are 2 of the contact slides that the rod slides into. (there is only one of these slides in the HL switch)
When you removed the ****/rod did you notice any burn marks on the rod ?
It is possible for the rod not to seat properly in the inner contact slide,this forces the slide beyond where it is supposed to be and might cross the contacts internally making the rod hot. Just thinking out loud. Here are 2 of the contact slides that the rod slides into. (there is only one of these slides in the HL switch)
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Willcox...
If a ground was placed into a circuit where it should NOT be...that is, before the normal electrical 'load' in the circuit...then it would cause a problem. But, if an existing ground wire is shorted to ground, it's still only a ground.
If a ground was placed into a circuit where it should NOT be...that is, before the normal electrical 'load' in the circuit...then it would cause a problem. But, if an existing ground wire is shorted to ground, it's still only a ground.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
In all the years we've been on here I don't know your name... I understand what you are saying... I'm thinking that a hot wire is touching the white wire... (ground)
Or.. something got on the rheostat.. possibly a ground.. and shorted it out.
It's really hard to say without having the thing apart and I'm going to look at this tomorrow a bit harder.
Last edited by Willcox Corvette; Jul 3, 2012 at 10:58 PM.
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Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Xterrable,is it possible you got the HL switch grounding bracket into the rheostat , that would create this kind of short ? The ground bracket is in red in this diagram.
http://willcoxcorvette.com/popup_image.php?pID=26692
http://willcoxcorvette.com/popup_image.php?pID=26692
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
OK, the white wire from the courtesy lights is only a ground wire when the doors are open. The rest of the time it really is just a wire that is connected to power through a couple of small bulbs. So, short it to ground and the courtesy lights come on. Short it to power and nothing happens until the door is opened and the door switch grounds the wire. The circuit doesn't have the power to burn anything unless a door is open.
So, did the meltdown occur while a door was open? If not, then it wasn't the white wire.
I still expect it to be an intermittent ground in the dash lights, especially since the OP has already stated as much.
So, did the meltdown occur while a door was open? If not, then it wasn't the white wire.
I still expect it to be an intermittent ground in the dash lights, especially since the OP has already stated as much.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
OK, the white wire from the courtesy lights is only a ground wire when the doors are open. The rest of the time it really is just a wire that is connected to power through a couple of small bulbs. So, short it to ground and the courtesy lights come on. Short it to power and nothing happens until the door is opened and the door switch grounds the wire. The circuit doesn't have the power to burn anything unless a door is open.
So, did the meltdown occur while a door was open? If not, then it wasn't the white wire.
I still expect it to be an intermittent ground in the dash lights, especially since the OP has already stated as much.
So, did the meltdown occur while a door was open? If not, then it wasn't the white wire.
I still expect it to be an intermittent ground in the dash lights, especially since the OP has already stated as much.
I think this short occurred on the non fused stud of the rheostat.
EDIT- Oops brain fart-the rheostat stud is fused through the 20 amp TAIL fuse-sorry.
Last edited by ...Roger...; Jul 4, 2012 at 12:40 AM.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
It is possible that the rheostat didn't pass enough current to blow the fuse due to the lights being dimmed yet got hot enough it melted down. The whole purpose of the rheostat is to insert resistance into the circuit and when you insert resistance you limit the short circuit current.
First check the green wire for the dash wiring which goes from the headlight switch to the fuse block. Check the fuse block too. Then, start checking the grey wiring. Check the dash light fuse and make sure it is the correct value.
Thread Starter
Racer
Joined: Oct 2011
Posts: 294
Likes: 0
From: Easton pennsylvania
Whoa.. Lots of stuff to answer here..
The **** was always difficult to get in and take out. Seems logical that you press the release and pull out or push it in. But I never got it on the first try. And yes, there were two lite burn marks on the rod. But I am pretty sure that was because the plastic around it was melting..
As for the ground, I dont see how it would be possible for the ground to touch the switch at all. I mean I guess anything is possible. But I may not have had it 100% tight. I remember being able to slightly spin the switch after it was installed. Not much, but it might not have been fully tightened.
Yes, both doors were open when this occurred.
The **** was always difficult to get in and take out. Seems logical that you press the release and pull out or push it in. But I never got it on the first try. And yes, there were two lite burn marks on the rod. But I am pretty sure that was because the plastic around it was melting..
As for the ground, I dont see how it would be possible for the ground to touch the switch at all. I mean I guess anything is possible. But I may not have had it 100% tight. I remember being able to slightly spin the switch after it was installed. Not much, but it might not have been fully tightened.
Yes, both doors were open when this occurred.
Thread Starter
Racer
Joined: Oct 2011
Posts: 294
Likes: 0
From: Easton pennsylvania
Well, I dont know if this was the cause or not, but I found 2 cut off wires that appear to have been cut at some point in the cars life. They are the Orange and White wires for the harness going to the rear of the car. They were cut about 2 inches from the plug, which plugs into the main harness near the fuse panel.
According to my wiring diagram, the Orange goes to the Battery Compartment Lite and to the rear glove box lite. And the white was the ground for them I believe..
If this was the case, are they turned on by/with the courtesy lights?
According to my wiring diagram, the Orange goes to the Battery Compartment Lite and to the rear glove box lite. And the white was the ground for them I believe..
If this was the case, are they turned on by/with the courtesy lights?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Well, I dont know if this was the cause or not, but I found 2 cut off wires that appear to have been cut at some point in the cars life. They are the Orange and White wires for the harness going to the rear of the car. They were cut about 2 inches from the plug, which plugs into the main harness near the fuse panel.
According to my wiring diagram, the Orange goes to the Battery Compartment Lite and to the rear glove box lite. And the white was the ground for them I believe..
If this was the case, are they turned on by/with the courtesy lights?
According to my wiring diagram, the Orange goes to the Battery Compartment Lite and to the rear glove box lite. And the white was the ground for them I believe..
If this was the case, are they turned on by/with the courtesy lights?
"IF" the cut orange is on the hot side of the plug and "IF" the orange and white were making connection,this would make the white HOT,this would make the brass finger in the HL switch HOT,if you rotated the HL **** to turn on the courtesy lights this would ground the HOT lead-should just blow the CTSY fuse. Lots of "IFs" but anything is possible.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
One has to wonder "why" those wires would have been cut. Maybe, there was some existing problem with the wiring and the PO cut them to eliminate the "symptoms". Perhaps the "cause" is yet to be found.
Thread Starter
Racer
Joined: Oct 2011
Posts: 294
Likes: 0
From: Easton pennsylvania
Thats what I am thinking. Odd place to cut them to... Odd thing is they were not just cut. They looked to have been cut and stripped at some point.
I did find that they spliced into the drivers side courtesy bulb wiring to jump power back to the Orange and White wires along the door sill. I cant tell of the backs works yet and the gove box light is missing and the cargo area was missing a bulb.
How the heck are the door switches wired? The ones that turn on the coutesy lights when the door is open? My drivers side has 2 wires on it and the passengers side only has 1. And I cant get any of them off... Was going to replace them because they are touchy. Some times they wont work, but the smallest touch gets them to work. Any suggestions?
I did find that they spliced into the drivers side courtesy bulb wiring to jump power back to the Orange and White wires along the door sill. I cant tell of the backs works yet and the gove box light is missing and the cargo area was missing a bulb.
How the heck are the door switches wired? The ones that turn on the coutesy lights when the door is open? My drivers side has 2 wires on it and the passengers side only has 1. And I cant get any of them off... Was going to replace them because they are touchy. Some times they wont work, but the smallest touch gets them to work. Any suggestions?
Last edited by Xterrable; Jul 5, 2012 at 11:17 AM.
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
When the door is closed the switches are open.
When you open the door the switches close and complete the circuit.
From the factory the drivers switch has 3 wires
one wire for the courtesy lights
one wire for the alarm and
one wire for the key left in ignition buzzer.
The passenger side has only 2 wires
one for the courtesy lights and
one for the alarm.
http://www.vetteprojects.com/bmv/mis...tte%201974.pdf
When you open the door the switches close and complete the circuit.
From the factory the drivers switch has 3 wires
one wire for the courtesy lights
one wire for the alarm and
one wire for the key left in ignition buzzer.
The passenger side has only 2 wires
one for the courtesy lights and
one for the alarm.
http://www.vetteprojects.com/bmv/mis...tte%201974.pdf
Thread Starter
Racer
Joined: Oct 2011
Posts: 294
Likes: 0
From: Easton pennsylvania
Gotcha. My factory alarm has been removed, so I assume they removed the extra wires.
What do the end of the wires look like? Are there special "clips' or something that push into the new switches?
What do the end of the wires look like? Are there special "clips' or something that push into the new switches?
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The ends of the wires have a "special" terminal that I could only find from a vendor and the switch also is vendor only.