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? 77 ac/heater control light

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Old Sep 13, 2020 | 04:46 PM
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? 77 ac/heater control light

There is a plug with two wires, one wire is Blue with a red stripe and the other is black. Its the plug with the light that goes in to light up the vent and ac/heater controls. I have the blue with red stripe one attached to 12v switch , but
The black wire is also hot , does the black wire go to the cig lighter?
 
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Old Sep 13, 2020 | 04:53 PM
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No, the black should be ground...
 
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Old Sep 13, 2020 | 05:00 PM
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Originally Posted by dlburch
No, the black should be ground...
Will its not. Its hot
 
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Old Sep 13, 2020 | 05:13 PM
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Old Sep 13, 2020 | 09:51 PM
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Is it hot with the lights off?
 
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Old Sep 13, 2020 | 10:38 PM
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describe exactly how you determined it was hot...you need to trace that wire to make sure it is actually grounded...if there are other circuits spliced into that ground circuit, and it isn't actually grounded, you could be reading voltage across other bulb filaments...
 
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Old Sep 13, 2020 | 10:44 PM
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Originally Posted by dlburch
describe exactly how you determined it was hot...you need to trace that wire to make sure it is actually grounded...if there are other circuits spliced into that ground circuit, and it isn't actually grounded, you could be reading voltage across other bulb filaments...
will I’m rewiring the truck with a universal harness and thought that the bulb needed a switched 12 v source so I connected it to one then the black wire touched ground and blew the fuse. So I replaced the fuse and stuck my meter to it and the black wire is show 12 v.
That is the reason why I was thinking it went to the cigarette lighter.
 
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Old Sep 13, 2020 | 10:47 PM
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I bought a schematic last yr on cd but now it won’t open or I would reading it to fine out how this two wire connection works with this plug.
 
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Old Sep 13, 2020 | 10:48 PM
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Originally Posted by John89
Is it hot with the lights off?
yes it is hot
 
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Old Sep 14, 2020 | 11:41 AM
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Is the pig tail from the socket part of the new harness?
Do you have the hot going to the headlight switch?

The oem socket would get its feed from the headlight switch and it's ground from the original plug.

It could be you need to run the black from socket pigtail to ground and not use the black from new harness. Or maybe the black one from the new harness goes to the radio backlight?


 
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Old Sep 14, 2020 | 11:51 AM
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Originally Posted by John89
Is the pig tail from the socket part of the new harness?
Do you have the hot going to the headlight switch?

The oem socket would get its feed from the headlight switch and it's ground from the original plug.

It could be you need to run the black from socket pigtail to ground and not use the black from new harness. Or maybe the black one from the new harness goes to the radio backlight?
This is the original socket , and no I did not connect the blue/ red wire to the headlight switch . I just tied it back into a switched 12v source.
So it’s blue/ red wire hot going into the light which is attached to the back of the vent control and it’s hot coming out the black wire.

It could be the light for radio, or cigarette lighter.
I’m about ready to just delete that pigtail all together since I’m only seeing it has a light source to able to see the controls.
 
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Old Sep 14, 2020 | 12:42 PM
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Cigarette lighter wire is normally a one wire from a 3 hole black none keyed 12V constant power source. That plug is over behind the glove box. And also has a Y that powers the glove box light. You can see the black wire that has the male plug for the glove box light. And that is where it Y 's to the cig lighter.



Here is is hanging out the bottom of the dash. Still on the passenger side. That big hole behind it it for the a/c evap box.

As far as the wire to the environmental panel backlight, it should not be hot unless you have the headlight switch out in 1st "park" light position or 2nd headlights on position.
 
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Old Sep 14, 2020 | 01:00 PM
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Originally Posted by 77&79F250
Cigarette lighter wire is normally a one wire from a 3 hole black none keyed 12V constant power source. That plug is over behind the glove box. And also has a Y that powers the glove box light. You can see the black wire that has the male plug for the glove box light. And that is where it Y 's to the cig lighter.



Here is is hanging out the bottom of the dash. Still on the passenger side. That big hole behind it it for the a/c evap box.

As far as the wire to the environmental panel backlight, it should not be hot unless you have the headlight switch out in 1st "park" light position or 2nd headlights on position.
ok so I need to wire it into the head light switch , but why would it be back feeding 12v to the black wire.
 
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Old Sep 14, 2020 | 01:17 PM
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I just added some input on the cig lighter wire question. Because that is all I got. I wish I had the answer for you on both of your other questions.

Yes when you turn on the park lights (headlight switch 1st out position) the instrument cluster, headlight and wiper switch backlight, environmental control backlight and front and rear "park" lights and all 4 side markers, and ash tray (?) are suppose to come on. Key on or OFF no matter. At least that is what I seem to remember. Can not go actually check at the moment. Disregard the "to radio" red circle that was another issue.

 
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Old Sep 14, 2020 | 06:30 PM
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Originally Posted by 77&79F250
I just added some input on the cig lighter wire question. Because that is all I got. I wish I had the answer for you on both of your other questions.

Yes when you turn on the park lights (headlight switch 1st out position) the instrument cluster, headlight and wiper switch backlight, environmental control backlight and front and rear "park" lights and all 4 side markers, and ash tray (?) are suppose to come on. Key on or OFF no matter. At least that is what I seem to remember. Can not go actually check at the moment. Disregard the "to radio" red circle that was another issue.
So i saw your picture and grabbed it. Do you know where the other end ties into? This is the one I'm dealing with .

 
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