@8.4-6.9L:
Right now, the CC is 100% dead. Drove it to Northern MI and was working OK, van sat for a week and NW on the way back. Pouring rain on the way up. Suspect a wiring connection under the hood.

It has been intermittently NW... try it again in 3-5 miles and would work and continue working. Seemed like I had minor problems with it before, corrected by cleaning the plug that goes into the servo. Have already checked this, checked vaccum switch at brake pedal. OK. Doubt it's a vaccum issue. This is about as far as I have gotten without a better understanding of how this works and where to look. This is early 80's tech and not rocket science. Electrical/mechanical stuff is fortunately my strong suit.

Has a manual trans meaning there is a clutch kill switch. Where?
Is the brake kill vaccum only or electrical as well?
I was under the impression the speed pickup was from the transmission? Never thought to look for pick up sensor on the speedo cable.
Checking the switches on the steering wheel worth consideration.

The problem with intermittent electrical problems is finding it.

Haven't had a free day to methodically get into this but is high on the list. I use this van for long haul eway and really want the cruise control working and reliable. It has to be something simple, most likely a fouled connector or stuck switch.

Side note: Had another Ford pickup with a persistent corroded connector problem that required cleaning every 60 days or so. Finally got PO, clipped the connector out and soldered the wires. End of problem. The back up light switch on this van has been another sore spot and about ready for some serious re engineering.

 

The pickup in my 84 is right under the mastercylinder on the speedo cable, and how much vac is your vac pump putting out?

Oh and my backup lights havent worked in many years, not like they were nice and bright to start out with. . . .

 

Thanks for that info. I took a quick look and it is where you said... and now I know what it is! Two wires means it is probably a coil pulsed by a rotating magnet: Pulse generator. Easy enough to test by resistance or removing it and bench testing it's output. Analog servo 101. I am going to get this in my shop, this weekend.

The backup light switch on this van is N.O. except when closed by shift linkage contact in rev. In the worst possible place as far as water, mud and salt. The plunger boot was shot, so made a new one. This is on my upgrade, list, too. Being a van and hard to see out the back, I need all the help I can get at night. I put halogen bulbs in as replacements BRIGHT!

Will post more when I get into the CC ring out.

 

If it is bad im told they are hard to find

 

Perhaps this info will be of some help to someone else with an '83 econosaur.I am generally following trouble shooting post earlier in this thread.

Update: I am about 6 hours, three bandaids, 3500 cuss words and a disassembled dash. into this. Maybe half way there? Most of the time spent looking for the servo amplifier box. Eventually located on RH side of the steeriing col support 3" from the dog house. To remove the dog house, the passenger seat has to come out. I managed to get the amplifier box loose in order to get at the input-output plugs. But not easy.

The input wiring colors differ from what was posted earlier.

Black#1=Ground
Black#2=Speedo cable sensor
Green =Speedo cable sensor
Black w/Green hash =11.5v+ with ignition on
White= Steering wheel control buttons
Red= Ground when either brake or Clutch is depressed, otherwise open.

Horn and brake lights check out OK...

Resistance values for control switches: (white wire and ground)
"set" 741 ohms
"coast" 250 ohms
"resume" 2200 ohms
Assuming control switches working OK

Removed tach from speedometer cable. Coil Tests 40 ohms idle. Connected with square bit to power drill, hooked to osciloscope , 2v sine wave out. Assume good. Clipped out the plug and soldered the connections, reinstalled.

Checked brake vaccume switch (removed and tested). Good.

I did however find a kink in the vaccume tube (causing a pinched closed state that would have prevented the switch from releasing vaccume. Occures to me I found this once before when I was having intermittent CC problems however it seems like this would simple keep the brake vaccume switch from working?) Fixed that.

Output from amp to servo. (These colors different that earlier post).
Orange
white w/Pink Hatch
yellow w/ red hatch
Black w/ blue hatch
grey w/ black hatch
Orange w/ green hatch

No clue which wire is which nor have tested the servo. The connection plug looks nasty and I suspect the problem is there. Need to figure out wiring color codes first before testing servo and continuity through this plug.

More forthcoming. Leave the dash disassembled and take a test drive. I need to pull the wiper motor anyway, which ought to be a breeze compared to this.