Cruise Control

[smtguy]

I have been trying to figure out how to get my cruise control to work. I have checked most of the things everyone says to do:
Fuse 6 - good
Brake lights work fine - new bulbs
Blue and white connectors attached to rear of the cluster (correct locations)
Control Stalk - changed out for a known good one
Control Box - changed out for a known good one
Pedal switches - test good, adjusted correctly - one normally open, one normally closed
Speedometer and OBC - all functions working correctly
Actuator connector - checked and cleaned

The one thing I have not figured out is how to test the actuator itself to see if it is functional. Does anyone have any ideas? What have I missed?
Thanks,
Scott

[Brucey]

I have been trying to figure out how to get my cruise control to work. I have checked most of the things everyone says to do:.....

Pedal switches - test good, adjusted correctly - one normally open, one normally closed.....

clutch switch is NC and brake light switch is NO but if it is the other way around then the system won't work




you can apply a voltage to the motor connections in the actuator directly, I think. I would imagine that you can test for clutch function and resolver function as well.

Note that there is more than one version of the cruise control and the wiring is slightly different for each.

[smtguy]

Thank you Bruce -
Yes the pedal switches are as you say. I will try putting 12V to the actuator motor and see what I get.
Scott

[Brucey]

12V is the maximum that the motor could see if there are no losses or voltage drops in the driving circuit. It may well run at a lower voltage than this, and not be rated for 12V so I'd suggest that you try a lower voltage first.

cheers

[tmoretta]

Can a fault in the cruise control system cause an engine skip? Once, while using the cruise control on my'88 M6 the engine was cutting out like it was shut off.

[Brucey]

Can a fault in the cruise control system cause an engine skip? Once, while using the cruise control on my'88 M6 the engine was cutting out like it was shut off.

yes, if the throttle is closed suddenly by the system, due to a fault of some kind

cheers

[tmoretta]

What should I check to diagnose fault?

[Martin S]

I had my cruise motor apart. Its a bit fiddly to put back together. Some springs and stuff that will frustrate you.
Anyway it wasnt the problem. My connector to the control unit under the dash had come loose.

Here is an excellent guide to troubleshooting the system if you havent seen it already:

http://www.theguestroom.net/e28/ideas/b ... 23-e28.pdf

[tmoretta]

Thanks so much