The red and black wires appear to be the plug for the capacitor for the vacuum solenoid. Without the capacitor connected, the tach will jump around especially when the vacuum solenoid is turned on and off. The capacitor + should connected to the micro-switch side of the vacuum solenoid. The OEM capicators were in the harness and usually had red and black leads that plugged in. You might trace the red lead on the plug to see if it is tapped into the microswitch side - I don't remember for sure but I believe the tap is located at the big white (9 pin) bulkhead connection. The ground - black is grounded at one of the connections on top of the manifold. For some reason I have found many of these disconnected and even cut out??? Harold McElraft - 3354 --- In dmcnews@xxxxxxxxxxxxxxx, "Farrar Hudkins" <fhudkins@...> wrote: > > I've checked the idle speed microswitch and the idle speed motor and > they're both working, as far as I can tell. (BTW, the idle speed motor > is not original -- it's newer. And so is the vacuum solenoid.) > > My problem is that I can't find anywhere to plug in the other end of > that lead! To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/