Hello Forum,
My 93 240 Wagon, has a cruise control.
It's electronically system works but usually speed down gradually after set. I looked at behind Brake booster at fire wall. There is a empty vacuum line, probably missing connection... Is this are reason why slows down?
And where it should be connected to?

Thank you for advice!!

 

I don't think anything's missing there. A gradual loss of vacuum means you have a slow leak somewhere: check all the vacuum lines, including the ones under the dash and the dump valve(s) at the pedal(s), and the bellows at the throttle.

 

Thank you! I will check vacuum lines and valves at pedals !

 

the cruise control unit on these cars was analog. if its old, and the capacitors in the circuit have gotten leaky, it won't hold a steady speed.

 

Thanks Pierce.
I checked all over vacuums lines, used electric taped at one of vacuum line elbow where was a bit suspicious. But after taped, still doesn't hold speed.
Now I can imagine condenser at circuit as you said. Where do you know the circuit located, any specific one or location? I can check later 240 when I go junk yard next time. Thanks!!

 

wiring diagrams show it behind the dash, above the steering column, down towards the firewall

 

I don't mean to derail this tread but is the cruise control on the Volvo 940's also analog? Mine is also not working at the moment.

 

Pretty sure it is. my 1992 740 doesn't have one, but I think even the cruise for my 1996 volvo 850 was analog (car is long gone).

on the mercedes from the same era, the circuit boards typically need resoldering, and maybe some capacitors replaced. advisable to use quality capacitors rated for industrial/automotive temperature ranges, once you figure out the values you need for a given board, you can order them from DigiKey Electronics - Electronic Components Distributor, they have about everything electronic you can think of in depth.

 

I haven't heard of cruise slowing down. Interesting.

My guess is bad diaphragm down at pedal.

 

That's just the vent for the cruise motor. Maybe that unit is bad. Idk.