Well, here goes the saga of the dead cruise control on the Thunderhorse:

I paid the Volvo dealership to diagnose the problem. I did not let them finish fixing the problem due to cost. They diagnosed the problem as a bad Cruise Control module. I knew it was not the servo or brake switch. I was unsure if the on/off switch and/or the module was bad, hence the dealership diagnosis. I had hotwired with my 12v electrical power converter the pump and it worked.

So I amble off to the junkyard and pull a module from a donor car, bring it home and plug it in. The test drive revealed it did not work, or so I thought. I started thinking about it and came up with a solution.

While driving, I pulled off the vacuum line from the servo. I then pushed the button to activate the system. I put my finger over the unhooked line and felt the vacuum pull activate. So I knew I had the module working and pump working but there was not enough pressure to operate the servo. I went home and parked. I was down to either a vacuum line leak or a weak pump.

I then hooked up my 12v power converter directly to the pump so it ran continuously. I got down and depressed the accelerator pedal, squeezed the servo closed and held it closed, then, while the pump was running, reattached the disconnected vacuum line to the collapsed servo. I then released the servo and discovered the vacuum created by the pump was not sufficient to hold the servo closed. I had an extra pump that I picked up a couple of years ago in the garage. I took the extra pump, attached power and hooked it up to the vacuum line under the hood and repeated the process. This time, the servo held shut.

I put a dab of silicone caulk at each joint where the rubber fitting met the vacuum line, just enough to seal if there was any tiny air leak. I then tookout the old pump, and put the extra pump in to replace it. Took it for a test drive and it works perfectly.

So not only did I have a bad module, but a bad/weak pump as well. If I had some vacuum hose pressure testers then I suppose I could have done it differently, but bottom line. I fixt it!!!
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93' 240 Classic Wagon 220K & 92' 740 Wagon Regina/Rex 90K