what is this black box for????????

junkman johnnie · Post by **junkman johnnie** » Sat Aug 12, 2006 3:34 pm

On my 70 F100, just above the gas pedal on the firewall is this little black box. It has 2 hoses which go threw the firewall, not hooked up. And 4 wires (red, blue, black) go into a 3 prong plug. And (gray and black, which is hooked up to the other black, to a 2 prong plug. Now bothb of the plugs are pluged into stuff under the dash. I don't know what either. The part # is DOAF-9E718. Ans in yellow stamp 9J2R. Now my truck was an automatic, but now a 4 speed. It did not have air, power steering, brakes. Could it go to the speed sensor? My speedo cable is in 2 peices. But they hook into this little flat, black, round thing with 2 wires. Can I remove these things and bypass the wiring?

Post by **FORDification** » Sat Aug 12, 2006 4:59 pm

Yes, this emission system can be totally removed and you would never know it. It is a NOx device that only allows the vacuum advance to work under certain conditions. When the outside temp. 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 temp. sensor, a sensor on the trans. and a control module with a solenoid valve for the vacuum. For automatics the trans. 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 temp. and/or speed. This emission system is a 'tack-on' like most of the first-generation types and is not a part of the main wiring harness.

Here's a picture of the speed sensor you're talking about:

...and here's a diagram of the layout of that system:

And just so you know, only the '70-'72 F100's have this, the F250/F350 trucks were exempt because of their higher GVW rating.

rjewkes · Post by **rjewkes** » Sat Aug 12, 2006 10:24 pm

wow mine didn't have anything but the door post sensor and the little control valve hooked up the vac lines bypassed that though.

milkman27 · Post by **milkman27** » Sun Apr 03, 2016 9:45 am

Soooo, can i use the said speed sensor as posted above as a source for say cruise control or maybe an electric speedo?

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what is this black box for????????

what is this black box for????????

re: what is this black box for????????

Re: what is this black box for????????