My speedo has wires!!!!!!!!!!!

Steve302 · Post by **Steve302** » Sat Dec 01, 2007 12:46 am

Hey everyone,
OK, on my speedo cable, located about halfway up my firewall is a little disk-like thingy built into my speedo with 2 wires coming out of it. the two wires go into the wiring harness....never to be seen again!
Just in case there is a difference in vehicles, its a 70 2wd f100 302 c4 california built truck.
Thanks, Steve

1971ford · Post by **1971ford** » Sat Dec 01, 2007 1:24 am

the cluster has 6 lights that can be turned on and dimmed with the headlight twisty turny thingy.
im guessing thats what it is.

Steve302 · Post by **Steve302** » Sat Dec 01, 2007 6:01 am

hey,
Nah dude, its on the other side of the firewall (engine bay) its inline with the cable, like a sensor or something
Steve

basketcase0302 · Post by **basketcase0302** » Sat Dec 01, 2007 7:34 am

Steve,

Just had to do it!

Would like to see that.

Jeff

Fake Name · Post by **Fake Name** » Sat Dec 01, 2007 9:23 am

I'm going to guess it for cruise control.

fn

Post by **FORDification** » Sat Dec 01, 2007 11:20 am

It's not for cruise control. Ford never offered cruise on these trucks. Here's the part you're referring to, correct?

It is a NOx device (part of a system called TRS or transmission regulated spark) that only allows the vacuum advance to work under certain conditions. When the outside temperature is below 60 degrees or so the vacuum advance is allowed...when it's above that temp, the vacuum advance is only allowed when the vehicle is traveling around 30mph or faster. The hardware and wiring to do this varied from '70-'72 but basically you have a temperature sensor on the driver's door pillar, a sensor on the transmission and a control module with a solenoid valve for the vacuum. For automatics the transmission sensor is a line pressure switch and for manuals it's just a mechanical switch that tells when it's in high gear. The control module switches the vacuum source on or off to the vacuum advance depending on the temps and/or speed. This emission system is a 'tack-on'Â

Fake Name · Post by **Fake Name** » Sat Dec 01, 2007 12:00 pm

Yeah, that's what I meant. Cruise control is actually short for Cruisenoxdevice, a registered trademark of Ford.

See, we're BOTH right ; )

fn

Steve302 · Post by **Steve302** » Sat Dec 01, 2007 12:10 pm

Thanks!

MaxKlinger · Post by **MaxKlinger** » Wed Dec 05, 2007 3:27 pm

Just had a big "Ah ha!" moment. I have the temperature sensor on my door frame. I thought it was from some kind of aftermarket security system installed by a previous owner. There is also some kind of relay mounted near the passenger side valve cover, I thought that was supposed to be part of the emissions system.

I still haven't passed NJ state inspection yet because my emissions are bad. I gave up, when I get Pennsylvania tags in Jan I should get a nice "Exempt" sticker and all will be well.

fordman · Post by **fordman** » Wed Dec 05, 2007 3:31 pm

that sensor inside the door jamb isnt for temperature. it has something to do with the emissions though.

MaxKlinger · Post by **MaxKlinger** » Wed Dec 05, 2007 3:37 pm

It looks just like the "Thermal Switch" in Keith's post above.

fordman · Post by **fordman** » Wed Dec 05, 2007 4:14 pm

yeah i guess i was thinking that you were thinking it might be for outside temp. i dont know why i thought that.

basketcase0302 · Post by **basketcase0302** » Wed Dec 05, 2007 5:47 pm

Wow!

That is some crazy stuff right there!
Never saw it before on a Ford.

Fordman, I didn't think our bumps had any kind of pollution control, (other than PCV if it's considered polution control)?

Basketcase

fordman · Post by **fordman** » Wed Dec 05, 2007 5:51 pm

well they did have a can on the frame of the 72's to revent the gas vapor back into the gastank. and i once again wasnt thinking about that temp sensor correctly. it doesnt have anything to do with the smog stuff. i had been looking for kieths pic in another thread and then i finally saw it open in this one.

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