I'm relatively new to this so pardon me if I'm beating an already dead horse. I have a 1979 450sl and I just replaced the cruise control amp with a reman unit. The cruise accelerates when engaged but will not hold speed. I recently changed tires from the standard 205 70 14 to 215 75 14. The cruise never has worked since I acquired the car and I added the new amp post new tires. Could this be the problem or should I be looking at the actuator? I've had the Benz for 5 years and I love it but I would love it more if the cruise worked! Any help would be greatly appreciated.
insofar as it has only ever worked intermittently, or in the "set the controls for the heart of the sun, I will accelerate you into oblivion" mode. I have a nother amp fitted, and no change. I haven't swapped the actuator yet, but it's a back burner.
The tyres wont affect the cruise, if they are all the same rolling diameter. and probably if they are not , either. Later cars with more complex ABS re easily upset, but I think the 107 is in the simpler end of the technology.
Thanks for the reply Elmer.
As an update to the problem, I resoldered all the joints in the original amp and it worked! But it too will not hold speed. I have check the actuator and it seems to be functioning properly. It tests out ok electrically and holds vacuum. I'm going after the transducer next to test it. Unfortunately this requires pulling the steering wheel and the instrument cluster and this 63 yr old can only take so much in one day.
I'll update the post after the next step.
...
Unfortunately this requires pulling the steering wheel and the instrument cluster and this 63 yr old can only take so much in one day.
I'll update the post after the next step.
Hey I can empathize with you. All the contorted positions we have to get in to do repairs. I've been down on the ground, feet upside over seat and head down on the floor looking up under the dash, flat on my back in the trunk ... sometimes I wondered if I would be able to get back up.
BTW, when you say won't hold speed ... does it feel like the actuator engages but lets the speed drift? If so, how fast is the drift?
FYI, I fixed the Cruise Control in my 560SL. I removed the circuit board and resoldered everything - still did not work. In my case the problem was that the cable from the Actuator was unplugged. It ran down in a well behind the passenger side headlamp and plugged in down in there.
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