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Cruise Control[200/1981] posted by Ben Hale on
Friday, 29 October 1999, at 12:36 a.m.
In my 240 my Cruise Control will not work. I have checked the connection to the break and to the back of the speedo. They are all connected. I also checked the fuse. Still nothing. I then turned it off then off again. Still nothing. Any suggestions. Thanks
Re: Cruise Control[200/1981] posted by John Kaiser on
Friday, 29 October 1999, at 5:02 a.m.
Check all of the vacuum lines for leaks. A vacuum pump works quite well for this procedure. Simply break into the accelerator servo and draw a vacuum on the system; the throttle plate should open, if not check for leaks.
--jk
Re: Cruise Control[200/1981] posted by Don Foster on
Friday, 29 October 1999, at 5:18 a.m.
Ben --
Check the connection to the control box -- it's a 4"x6" black box made by Dana Corp, usually mounted on the inside firewall near the passenger's feet, above the kick pad.
The cruise control MUST shut down when you hit the brakes -- it does this two ways: by a positive signal from the brake light switch, and by a loss of vacuum signal at the brake pedal.
Be sure the vacuum line at the brake pedal is completely closed (blocked, or obscured) when the brake pedal is up. A clearance (or an opening) of as little as 1/16" will bypass vacuum and prevent operation.
In one of my cars, I had to resolder the control box to restore operation -- but I suggest you leave that diagnostic to last. Check the easier things first.
--Friday, 29 October 1999, at 5:24 a.m.
Could also be the turn signal stalk. Worked on an '86 244DL that had a dead cruise control system. Discovered that the switch on the stalk was dead. Also had this problem on another 244 ('81).
-J
'76 245DL, 212K km; '81 242GLT, 454K km; '84 245GL, 408K km; '85 245GL, 330K km; all with M46 and all in Seattle
John's Brick Page
Re: Cruise Control[200/1981] posted by Chris Marchlewski on
Friday, 29 October 1999, at 11:20 a.m.
Look at the firewall where the cruise control wiring enters the engine compartment. If there is a tubular looking thingie about 1/2 inch by 1 inch long attached to a bracket which is screwed into the firewall next to the wire bundle, this may be the problem. It is a mercury switch which is tilted at an angle so that if the car encounters sudden deceleration (as in driving off the road into the grass as you doze off) it would shut off the cruise so you would (hopefully) stop before you went too far.
This switch was bad on my car and resulted in an inop cruise control. Later models did not have it. It could be the bracket is bent, more likely the switch is not contacting. I jumpered the wires and the cruise worked fine immediately.
This was a mystery to everyone I asked until one dealer mech remembered it.