Cruise Control Issue 89 911 Carrera

[benhere]

The decrease speed function on my 89 911 Carrera cruise control switch does not work. The speed set, accelerate, and cancel functions work, but when I pull down on the lever to decrease speed, nothing happens. When I step on the brake, it cancels the speed control. Not sure if the problem is in the switch, control unit, or? I went through the wiring schematic, but not sure just where to check. Appreciate any input.

Thanks
Ben

[86 911 Targa]

Originally Posted by 86 911 Targa

If you have a Bentley manual, the trouble shooting steps are listed.

[Autoban]

On my '86 cruise control I don't think there is a speed decrease function. Moving the lever up is to set the speed and to accelerate, pulling the lever is to cancel and pushing it down is the resume function.

Juergen

[uwanna]

Originally Posted by benhere

The decrease speed function on my 89 911 Carrera cruise control switch does not work. The speed set, accelerate, and cancel functions work, but when I pull down on the lever to decrease speed, nothing happens. When I step on the brake, it cancels the speed control. Not sure if the problem is in the switch, control unit, or? I went through the wiring schematic, but not sure just where to check. Appreciate any input.

Thanks
Ben

When you pull down on the lever, you activate the "resume" feature. There is no decrease speed feature. If you cancel while using CC, then want to go back to the speed you had set, you pull down the lever to resume.

[RSBob]

+1 no decrease or increase speed functions. Your manual will not have anything about either. Set, resume and cancel are it. 80s technology at its simplest.

[uwanna]

Originally Posted by RSBob

+1 no decrease or increase speed functions. Your manual will not have anything about either. Set, resume and cancel are it. 80s technology at its simplest.

Indeed there is an increase feature. While cruising at speed, just lift up on the lever, and your cruise speed will increase accordingly and become the new speed.

[pavegeno]

There should be a sticker on your dash behind the cruise control switch showing the functions of the switch. Perhaps someone removed it because it only shows cancel, set/accelerate, and reset. No slow down function. You have to disengage the system, slow down and then re-engage. My only gripe with my car.

Porsche 911 (1974-1989) - Interior Accessories - Page 4

[pavegeno]

[pavegeno]

Confirm your 89 is a 3.2 and not a 964C4. Not sure if 964s improved the cruise control to incorporate a decelerate function.