Right now in my bay I have a 1988 300E That the cruise doesn't work but used too.

A little backstory.

Customer brought car in with a car that the cruise control worked but would cut out randomly. So I measured amp draw on the actuator (well within spec) so I ordered an amplifier (remanufactured programa brand). Installed amplifier, took it for a 15 mile spin and cruise worked flawlessy.

A couple of weeks later customer comes in a little irate, still complains of it cutting out randomly (would cut out and not work till the next day).

Took it for a spin. hit set/accell, car revved up and bam no cruise control. Wouldn't work at all.

I removed the actuator and found 2 teeth missing on the inside....no biggie, order an reman programa actuator from peach parts.

Hooked up actuator and still no cruise.

Here's what I went over so far.

Tested switch, all ohmed out ok. And then checked power out from the switch all good.

Tested continuity from actuator plug to amplifier plug, all good.

Tested reference resistor all good.

Tested hall effect sensor on back of cluster, had 60hz at 30mph at the X53/5 Junction and at the amplifier plug.

I have power at the switch and the amplifier plug.

Verified pin 8 brake like circuit is good. (good ground with no brakes, 12v with brakes applied).

Tested grounds, all ok.

I even called programa tech support. He told me it was vacuum related......

I must be missing something. Thanks!