Your Cruise doesn't work? Try this!
Thread Starter
Super Member
Joined: Feb 2008
Posts: 844
Likes: 1
From: Orland Park, Illinois
1994 E320 (current)
Your Cruise doesn't work? Try this!
So My cruise control mysteriously (but not surprisingly) quit working just before my 1200 mile round tripper to Ohio. I couldn't figure it out. everything that could have been the culprit was in working order. Then while in Ohio my brother in-law, who was driving behind me, said "you definitely have a short or something in your brake lights, they came on on when I know you weren't braking, you should check it out."
Sure enough he was right. There is a spring that keeps the brake pedal pulled all the way up when you are not pressing it. It has worn and is sagging just enough to trip the stop lamp switch and therefore not allowing the Cruise control to engage.
So before you go and replace the throttle accuator simply put your foot under the break pedal pull it all the way and give your cruise control a try.
Go to this link and scroll down to item 42-4040 - Removal and installation of mechanical stop lamp switch.
there is a picture there that shows the spring and stop-switch.
http://www.ps2cho.net/downloads/MB%2...rakeSystem.htm
Don't know if I have to get the whole stop lamp switch or if I can get just the spring. We will find out. I am going to try and adjust it first but don't know if that can be done. I will re-post with my findings on both.
Sure enough he was right. There is a spring that keeps the brake pedal pulled all the way up when you are not pressing it. It has worn and is sagging just enough to trip the stop lamp switch and therefore not allowing the Cruise control to engage.
So before you go and replace the throttle accuator simply put your foot under the break pedal pull it all the way and give your cruise control a try.
Go to this link and scroll down to item 42-4040 - Removal and installation of mechanical stop lamp switch.
there is a picture there that shows the spring and stop-switch.
http://www.ps2cho.net/downloads/MB%2...rakeSystem.htm
Don't know if I have to get the whole stop lamp switch or if I can get just the spring. We will find out. I am going to try and adjust it first but don't know if that can be done. I will re-post with my findings on both.
Thread Starter
Super Member
Joined: Feb 2008
Posts: 844
Likes: 1
From: Orland Park, Illinois
1994 E320 (current)
So it became apparent that just tightening the spring that pulls the pedal up won't work but here is what will. There is an area on the break pedal where the stop lamp switch rest and while it is resting it has a closed switch (using a plunger post) when you press the pedal it goes away from the switch and open switch activates the brake lights and deactivates the cruise. So for $1.97 at Lowes I got a small roll of 1/2 inch wide 1/8 inch thick adhesive back magnet. I cut a 1/2 inch x 1/2 inch piece and stuck to the area on the brake pedal so it is between the switch and the brake pedal, that removed the play in the pedal and switch contact and problem solved.
