metal plate in door jams?

[michael]

Anyone have an idea on what the metal plate with two wires is, in the door jams of my 72 ranger lwb.

[FORDification]

I tried to answer this question when you e-mailed me directly, but it got returned to me, saying there was no such user at the e-mail address you used.

You're referring to the dome light switch brackets. Since the dome light switches are plastic, they get brittle with age and break apart, and fall out. You just have to get a couple new switches, mount them in the brackets and plug in the wires.

[michael]

Sorry about the email thing. Im changing email addresses. Im actually talking about a metal tab thats below the interior switch. Any idea's?

[FORDification]

Is this what you're talking about?



That's a thermal switch which is part of the emission controls installed on F100s....the F250/F350 trucks don't have that, though they do have an empty hole. It's not needed.

[michael]

thats it. Im an A.S.E. crtified master tech so I under stand emmision controls but I cant figure out what the trermal switch is doing in the door jam. Any information would be greatly appreciated. Love the site and have recommended it to several of my buddy's with ford trucks.

[FORDification]

I guess I can't tell you a specific 'why', except what I've heard. As I understand it, it was simply a convenient place to install, close to the engine (so shorter wiring) and away from the engine compartment's heat, plus it would easy to access for testing/replacement if need be.

[Ranchero50]

now I know too... Figured it was redundant for another older style switch...

[68F250]

thats it. Im an A.S.E. crtified master tech so I under stand emmision controls but I cant figure out what the trermal switch is doing in the door jam. Any information would be greatly appreciated. Love the site and have recommended it to several of my buddy's with ford trucks.

Are you asking why a thermal switch or why is the switch in the door jamb?

Called Transmission Regulated Spark or TRS, the system is a glorified NOX control that connects and disconnects the vacuum advance depending on vehicle speed, the thermal switch disables all of it when the outside temperature gets cold.

Why have a thermal switch? Allows better driveability in cold weather. Why in the door jamb? Most convenient place to measure outside temp. without being influenced by other factors.

The system Keith posted with the big box and speed sensor began use in '70, here's a simplier system used in '71 and later, the box was expensive so they engineered it out. (As Keith stated only F100's required this NOX device):

[cantool]

Hey! That's the very thing I was asking about. Since I'm the third owner of my truck, and aquired it with nothing other than the TRS hooked to my ignition and tranny, it gave me no benefit other than watching it fry, along with the wiring attached to it. On the other hand, now I know that I will have to strip all of the wiring out of the dash just to localize and perhaps solve my problem !

[bugser]

I'm confused. I have this thing in the jamb but don't believe anything is hooked to it,like a box under the hood.

[cantool]

Hey bugser,
Remember when ignorance was bliss?! Now armed with some knowledge 'bout that strange 'thingy'...
There were 2 PO's of my truck that must have taken care of any modifications like removing the little black box,hehe, and the original carb with the various solenoids.
So, cheer up fellow ford p/u man!!

[cghstrojan08]

Is there supposed to be two of the dome light switches? I just have one in my driver side but my parts truck had two.

[Tim P.]

Is there supposed to be two of the dome light switches? I just have one in my driver side but my parts truck had two.

my 68 had only one so I put two in Im speculating that it was an option to have two one on each door.
bty I have a set of nos new switches and the brackets if any body is looking to replace or add this to there truck.

[cantool]

I can only answer for my 72 sport custom, one in each door. Could be that it was an option in earlier models.

[cghstrojan08]

There is holes to mount one but no wires.