This switch is off a '91 3.0 V6, manual.

It was attached to my cruise control, at least attached in that general area and tee'd vacuum from it. To be honest, not really sure if the switch relates in any way besides loaction. Has one vacuum port and one plug with two wires. Just slightly larger diameter than a quarter.

The numbers 559-0Z00 and 170NB are on the top.

Just trying to figure out what it might do and if I need it, as my cruise control has been removed.

 

To be honest that doesn't look like anything I've seen in my truck and its a 91 V6 manual. It would probably be easier to ID it if you had a pic still in the truck. Hopefully someone else will chime in though

 

By looking at my parts image I'm guessing that it's the vacuum speed control switch. It mounts to the cruise control bracket right? If so then that is what it is.

 

It does mount to the CC bracket.

So, what does it do then?

Like I said, my cruise is now gone, so should I just plug the vacuum line and disconnect electrical plug... or is that going to confuse my ECU or other?

Thanks

 

I believe its a simple vacuum switch. It's purpose would be to kick out the cruise if vacuum falls too low for too long, like if you were lugging up a hill. It provides a ground to the CCC, (same as the brake light switch does) which shuts down the cruise. If you think it's bad, plug the vac line and unplug the connector and try your cruise. I would also check the cruise brake light switch, they are notorious for vacuum leaky or simple misadjustment. Then check the park brake switch, neutral safety switch (if auto) and clutch switch...

(edit) I just realised you meant the cruise is removed, not broken... Plug the vac line.

 

Thanks for all the help.

I will just plug the line then. I am a average mechanic, and the thing that was throwing me was that the last owner (or mechanic) had this mystery switch getting its feed from the TVV at the back of the block.

This seems wrong in all of the manuals I can find. It looks like the TVV is supposed to come from the charcoal canister and then on to the throttle body, not on to this CC switch as my vehicle was.

I think I will eliminate the CC switch, and hook up the vacumm lines from the TVV like the manuals show.