Cruise Control on 1994 940 Turbo Needs Work -- But What?

rob2volvos · Post by **rob2volvos** » 06 Jan 2011, 10:31

Over the past few months, the cruise control on my 1994 940 has gradually malfunctioned to the point now where it barely works. I get up to speed, press the cruise control, the speed might drop to 5-10 mph below the target speed and I can feel it pulling but it's weak and fades. So it's as though the vacuum isn't being held properly (and I suspect the colder weather has made the problem worse).
Last weekend, I inspected the associated vacuum tubing, the pump mounted on the driver's side strut housing and the rubber bellows-thingie hooked to the accelerator cable and it all looks fine -- nothing obviously wrong. Can anyone comment on this / suggest a good testing procedure to troubleshoot the issue?

Much Obliged,

Rob

Kirby J · Post by **Kirby J** » 06 Jan 2011, 10:51

Mine does the same thing, and I have also found no vacuum leaks. I have found that after the car is fully warmed up, the cruise works just fine. I suspect old hardened lines that only leak when they are below 40F. Or maybe it is a lubrication issue-very cold grease does not work as well as warm grease.

Kirby J
93 945 391k and counting

Post by **billofdurham** » 06 Jan 2011, 12:42

You can connect the cruise control module to the OBD unit and pull diagnostic codes.

The attached shows how:

940 Cruise Control Diagnostics.pdf: (3.66 MiB) Downloaded 250 times

Bill.

rob2volvos · Post by **rob2volvos** » 06 Jan 2011, 12:48

Thank you both for very helpful posts.

Hey, Bill -- You have quite a stack of useful PDFs in your back pocket -- Good Man!

Rob