What is this wire for? I found it under the floor on the drivers side of my 78 bronco. I think the wire color is light blue. Is it for a brake sensor?

johnnyreb

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I found this light blue wire. Under the frame . On the drivers side of my 78 bronco. Is it for a brake sensor? It had NO power on it .With the switch on or off.
 

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OX1

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I think that is for reverse light switch if you have a NP435 or T-18 man trans.
 

johnnyreb

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I think that is for reverse light switch if you have a NP435 or T-18 man trans.
Thanks ox1. With these vehicle manufactures mixing up all the wire different colors only tells me. Its a way they want a person to take it to their dealersship. They could keep it--like for reverse light-one color. When the weather breaks and it drys up. I,ll hit back on it. . I tested the light with a wire straight off the battery and they work. I have it all traced down to the yellow and black wire coming off the back of the fuse block. Its no power between the wire coming out behind the fuse box to the wire that hooks up to the reverse unit on the transmission. . When I hook the hot wire to the transmission switch .It has power going in and coming out-but their is a break between it. I,ll check it again,and getting close to solve it. Its not gonna beat me. I,m just as stuborn and determined . Its put me through alot,but I gonna beat it. Thank oxy. I appreciate it. Now I,ll have to track the blue wire in reverse to see where it leads to. Thanks alot. It has the manual hubs an t-18. That t-18 transmission goes back a good while. I have a 56 that has it. Alot of the big trucks and in different makes has it.
 

johnnyreb

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I think that is for reverse light switch if you have a NP435 or T-18 man trans.
I went back out. It was start to rain,but I went ahead and found under the hood on the drivers side. A light blue wire with a plug on it. I had to quit because it started raining more,but its not too long.So I will keep looking and let you know what I find out.Thanks alot.
Ox1
 

johnnyreb

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I went back out. It was start to rain,but I went ahead and found under the hood on the drivers side. A light blue wire with a plug on it. I had to quit because it started raining more,but its not too long.So I will keep looking and let you know what I find out.Thanks alot.
Ox1
I found this 78 bronco wire diaphgram on the net and hope it is alright and helps someone. I noticed the black and red wire off the switch and on the back up lights. I think what might have confused me some was. I had some wires under the hood burn. During the fire I had under the hood a couple of years ago. I,ll try and get the picture on
 

johnnyreb

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this is a pretty good diaphgram. It tells the color and shows where they go. Thanks OX1. I appreciate it alot.
What it does not tell you is that it travels up along the frame on the drivers side up to the firewall on the drivers side above the steering colum. Some where between the rear frame to below the drivers door it joins 1 light blue wire. I,d say that is where the light blue wire plus into. Then the light blue wire travel up the firewall on the drivers side and this is where it end with anothe (male ) plug in. Now the 2 wire that come off of the transmission switch has 2 wires on that switch. Which are a red and black wire---pus another wire that looks black. . I say the switch --switches over the hot wire their going to the back up lights. If it quits raining I,ll find out more and keep you posted. Thanks Oh their is a two wire plug in buts they are yellow and black plus a black wire and it runs to the light switch.Then to the fuse block. I ,ll check more on it when the rain stops.Thanks.. From what I see on this diaphram. Form the transmission. It runs to the heater switch. That could be my problem. Those wire did get bunrt and I had to cut some and replace them. i,LL CHECK THEM AGAIN AND MAKE SURE.tHANKS. i HOPE THIS PICTURE HELPS SOME ONE TOO.
 

johnnyreb

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What it does not tell you is that it travels up along the frame on the drivers side up to the firewall on the drivers side above the steering colum. Some where between the rear frame to below the drivers door it joins 1 light blue wire. I,d say that is where the light blue wire plus into. Then the light blue wire travel up the firewall on the drivers side and this is where it end with anothe (male ) plug in. Now the 2 wire that come off of the transmission switch has 2 wires on that switch. Which are a red and black wire---pus another wire that looks black. . I say the switch --switches over the hot wire their going to the back up lights. If it quits raining I,ll find out more and keep you posted. Thanks Oh their is a two wire plug in buts they are yellow and black plus a black wire and it runs to the light switch.Then to the fuse block. I ,ll check more on it when the rain stops.Thanks.. From what I see on this diaphram. Form the transmission. It runs to the heater switch. That could be my problem. Those wire did get bunrt and I had to cut some and replace them. i,LL CHECK THEM AGAIN AND MAKE SURE.tHANKS. i HOPE THIS PICTURE HELPS SOME ONE TOO.
Well I went and looked at mine and its NOTHING like this diaphgran. I,ll fix it like the COMMON MAN. Run a lighted switch to it. Alot easier then trying to do it the factor way. Besides of all the wires going into one are and one fuse. You,d think it would be a fire hazzard. One wire with a fuse would be safer.
 

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this is a pretty good diaphgram. It tells the color and shows where they go. Thanks OX1. I appreciate it alot.
I ran the yellow and black wire to the light switch. Its getting power from the light switch. I traced the yellow and black wire on the diaphgram to the fuse box. I check all the fuse and one WAS DID NOT light up my tester. Its raining again and when I get the chance. I,ll look at it more closely and TRY to find out what is wrong their. It might be my problem.
 

OX1

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Thanks ox1. With these vehicle manufactures mixing up all the wire different colors only tells me. Its a way they want a person to take it to their dealersship. They could keep it--like for reverse light-one color. When the weather breaks and it drys up. I,ll hit back on it. . I tested the light with a wire straight off the battery and they work. I have it all traced down to the yellow and black wire coming off the back of the fuse block. Its no power between the wire coming out behind the fuse box to the wire that hooks up to the reverse unit on the transmission. . When I hook the hot wire to the transmission switch .It has power going in and coming out-but their is a break between it. I,ll check it again,and getting close to solve it. Its not gonna beat me. I,m just as stuborn and determined . Its put me through alot,but I gonna beat it. Thank oxy. I appreciate it. Now I,ll have to track the blue wire in reverse to see where it leads to. Thanks alot. It has the manual hubs an t-18. That t-18 transmission goes back a good while. I have a 56 that has it. Alot of the big trucks and in different makes has it.

IIRC, there was also a jumper wire that connects two wires together that is only used if you had man trans.

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Some more info........


 

johnnyreb

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IIRC, there was also a jumper wire that connects two wires together that is only used if you had man trans.

You must be registered for see images attach


You must be registered for see images attach


Some more info........


The wire on mine has one wire on it. The wire (2) that comes off of the 4 speed has a red and black wire and the other wire is black. Their is another (plug) that comes up to it. That has 2 wires. A black and yellow wire with a black wire. I checked it for power with the switch on both ways and it does not have power. I traced the yellow and black -with the black wire behind the dash. The yellow and black wire . Goes to the light switch. I tested the light swith and a couple wires did not have power. Including the yellow and black wire. So its pointing the light switch may be bad. I,ll buy a new Ford America made switch this week. From Green Sales Parts this week. Thanks for the help.
 

johnnyreb

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The wire on mine has one wire on it. The wire (2) that comes off of the 4 speed has a red and black wire and the other wire is black. Their is another (plug) that comes up to it. That has 2 wires. A black and yellow wire with a black wire. I checked it for power with the switch on both ways and it does not have power. I traced the yellow and black -with the black wire behind the dash. The yellow and black wire . Goes to the light switch. I tested the light swith and a couple wires did not have power. Including the yellow and black wire. So its pointing the light switch may be bad. I,ll buy a new Ford America made switch this week. From Green Sales Parts this week. Thanks for the help.
I could not see or find a saftey switch on the transmission. When it gets dry and stops raining. I,ll check my 75 Ford F-600 and see if it has any on the transmission. I think its a 5 speed. It has back up lights,but they are usless. They are mounted inside the frame and doesn,t show any light to see buy .From inside the cab. M 56 c-600 you can see and the light is in the middle of the frame. It has about a 5 inch bulb and lights the area up good.
 

johnnyreb

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I think I found out the reason my back-up lights won,t work by the back-up light switch. I checked all the wires coming out of the light switch and all but one or two does not light up my tester. Tomorrow I,m gonna see about ordering a new one from Green sales Company.
 

OX1

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One other possibility for that connector, which I totally forgot about, was the 203 case "lock"
under dash light. I remember seeing that single connector in many of my bronco's, but of all
the one's I had over the years, only 1-2 had the 203 case and they were both parts trucks.


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After more digging, it seems T-18 and 435 both used the same 2 wire connector, so the back up light thing is out.
You must be registered for see images attach
 

johnnyreb

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One other possibility for that connector, which I totally forgot about, was the 203 case "lock"
under dash light. I remember seeing that single connector in many of my bronco's, but of all
the one's I had over the years, only 1-2 had the 203 case and they were both parts trucks.


You must be registered for see images attach


After more digging, it seems T-18 and 435 both used the same 2 wire connector, so the back up light thing is out.
You must be registered for see images attach
I remeber my brother,s 76 Ford had about 4 light (oem) under it,but I think they were all RED. Mine does not have any lights under it and its a 78.
 

miesk5

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Yo Johnny,
A guess because my memory is shot about our former 78 w/203; this is from my MS WORD notes:
"he wire on the NP 203 goes to a simple blue light that's about the consistency of the blue light on the instrument panel for when the bright headlights are on) on the bottom dash located just to the lower right of the ash tray. Whenever you shift the NP 203 into the lo-lock or high-lock position, a small blue display will light up the word "LOCK".
Usually wire was broken off due to a passenger sitting in bench seat center position accidentally kicked it.
 

johnnyreb

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Yo Johnny,
A guess because my memory is shot about our former 78 w/203; this is from my MS WORD notes:
"he wire on the NP 203 goes to a simple blue light that's about the consistency of the blue light on the instrument panel for when the bright headlights are on) on the bottom dash located just to the lower right of the ash tray. Whenever you shift the NP 203 into the lo-lock or high-lock position, a small blue display will light up the word "LOCK".
Usually wire was broken off due to a passenger sitting in bench seat center position accidentally kicked it.
Well mine doesn,t have the light under the dash,but someone could have taken it off. I remeber my brother had a 76 4 wheel drive and it had I think about3-4 lights on a black plate and writing on it. I ,ll keep looking and working on it. I did find a couple of bare wires .Where they went through the rear frame support and it looks like they got hot. I have taken a couple of pictures and see about getting them posted. Thanks Mike.Hope your feeling better and thank you and all veterans and those who are serving and protecting our freedom.
 

johnnyreb

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Well mine doesn,t have the light under the dash,but someone could have taken it off. I remeber my brother had a 76 4 wheel drive and it had I think about3-4 lights on a black plate and writing on it. I ,ll keep looking and working on it. I did find a couple of bare wires .Where they went through the rear frame support and it looks like they got hot. I have taken a couple of pictures and see about getting them posted. Thanks Mike.Hope your feeling better and thank you and all veterans and those who are serving and protecting our freedom.
My brothers was a FULL TIME 4 WHEEL DRIVE WITH AUTOMATIC. Mine is a 4 speed
 

johnnyreb

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One other possibility for that connector, which I totally forgot about, was the 203 case "lock"
under dash light. I remember seeing that single connector in many of my bronco's, but of all
the one's I had over the years, only 1-2 had the 203 case and they were both parts trucks.


You must be registered for see images attach


After more digging, it seems T-18 and 435 both used the same 2 wire connector, so the back up light thing is out.
You must be registered for see images attach
Thanks OX1. i,ll keep looking. I found some ***** wires yesterday . Going through the rear frame cross member. Seems the rubber grommet had rotted into and slipped out and all the years--it rubbed the wires bare. I took some pictures and will post them later on--hopefully today. I think their was a light blue wire their too.
 

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