Ed Petry

Morning everyone,

I recently tested my cruise control system and resolved to the control unit. Had the control unit serviced and the cruise operated. Now it has stopped. I retested the system this weekend with the same result as before. Appears the control unit is the issue.

BUT...

Tracing through the schematic shows the signal passes through the Lamp Control Unit and the speed sensor which is connected to the Instrument Cluster which is connected to the Central Warning system.

My questions is: Does the Lamp Control Unit or Instrument Cluster or Warning light circuits affect the cruise control? In other words, is the cruise control dependent on the instrument warning lights operating properly?

Thanks in advance.

gazfish

It connects in parallel with the lamp warning unit and relies on current though the brake bulbs, if you've replaced the brake bulbs with LEDs or don't have functioning brake lights for some other reason your cruise won't work. Have you done anything near the clutch switch recently as that will also disable it?

Gerald Finden

How are your motor mounts? I have heard if your engine settles too far, your cruise control may quit working.

chakka

I have the brake warning light on(sometimes). My brake lights all work(I replaced all of them), cruise works most of the time even though the light is on. I had the warning light come on and the cruise stopped working last week, but now its working again. I'm still routing thru the grounds, but nothing seems to change consistently. Also, going to clean the fuse contact for corrosion. I had replaced the fuse months ago, but probably change that again. It's a quirky beast of a car....

GregBBRD

"Cruise control unit" rebuilding generally consists of re-soldering the circuit board and shipping it back.
Generally, not much "testing" occurs....
You might want to try another unit, before you beat yourself to death.

Mark Anderson

I have tried a few different rebuilders with a wide variety of results

Mrmerlin

Umm try Kris Rose Mercedes Benz HVAC repair,
he has been 100 % for me,
with 10 units so far all working perfectly.
IIRC he replaces the the tower looking part on the board,
and a few capacitors and a couple of other things ,
about 100.00 per unit shipped.

Billu

I would second that. Have bought rebuilt units that sort of work sometimes, but his work on my unit now give total “non-surging” cruise.

Ed Petry

Thanks, everyone. I will look into your suggestions. More later.

928NOOBIE

...I would have never known about this had I not been in right place at right time. Thanks for sharing; I love learning more about our cars...especially these kinds of things...makes me love mine even more.

GT6ixer

Do you have a contact for Kris? Website? Business Phone?

Billu

www.CruiseControlRepair.com