Cruise Control Question - 986 Forum

Cjamerson1212 · 08-31-2018, 06:05 AM

Can anyone explain the behavior of a cruise control that is not properly grounded?

My Car: 1998 Boxster 2.5L

The CC light comes on when I start the car, then goes out after a few seconds.
The CC light comes on when I press in the CC button on the stalk.
The CC light stays on when I try to activate CC. (pushing stalk forward)
The CC light momentarily goes out when I reset CC (pull stalk backwards)
THEN after attempting to activate CC a bunch of times the CC light will go out and not come back on until I restart the car. Anyone know what this means?

Here is my particular run down of events:
- Bought the car in June, and could not get the cruise control to work.
- A few weeks later.. It randomly worked!
- Found water under drivers seat.. pulled all carpet out and hopefully fixed leak.
- Replaced headlights, side markers, brake lights, and 3rd brake light with LED's.
- Replaced both the brake and clutch switches. While I was under the dash I found a random loose black wire that was attached to the front wall next to where the steering column exits the cabin. The other end of the 8-10 inch wire was corroded and didn't look like it was connected to anything. I ended up ripping it out.
- I installed a load resistor on the left tail light; still no CC.
- I moved the load resistor to the 3rd Brake light wire... Still no CC.

Now I'm kinda wondering if the random black wire I found could have been a poorly installed ground for the cruise control??
I'm in the process of upgrading to a double din stereo and have already removed the instrument cluster to run the microphone/ GPS lines how I want. I'm going to go ahead and remove the steering wheel and see what I see.

Any help would be greatly appreciated.

Boatin · 09-05-2018, 01:05 AM

I got my 2003 Boxster S about 6 months ago (now 214K klms). The CC has always been intermittent. Sometimes it would work straight away and sometimes I would have to keep trying it. I saw somewhere that the Brake Pedal Switch might be the problem. Cost of switch in Sydney $50 delivered. Maybe it just needs a clean, so I pulled the switch out squirted lubricant into it, exercised it and reinstalled it. With much anticipation I took her for a drive. NO CRUISE CONTROL at all. Bugga. Then today I thought that this switch turns the brake lights on and disconnects the CC when you apply the brake pedal. Maybe it is just an adjustment that is required ? So I cut a small rectangle of cardboard (from a business card) and a small strip of duct tape and stuck this on the brake pedal arm between the arm and the contact point of the plunger in the switch. Another test drive and CRUISE CONTROL WORK EVERY TIME !!!!! Another problem has been that the PSM and ABS lights come on at some time every drive. I am hoping that this may be solved also.

Anker · 09-05-2018, 07:01 AM

An even better fix is to pull on the plunger on the switch. If you pull it all the way out it will adjust to the correct length the first time you release the brake pedal.

Push the brake pedal down, pull on the plunger and it will come out and you will feel the ratchet. Release the brake pedal and you are good. Do the same with the clutch pedal for good measure!

Boatin · 09-05-2018, 10:13 PM

Thanks Anker, Took her for a spim this morning. No CC. Suspect the tape didn't stick very well. Depressed the brake pedal and pulled on the switchplunger. Didn't seem to want to move, then I heard it click.

Cruise Control Working. Now still waiting to see if the PSM and ABS lights come on.