I have been trying to get my cruise control to work. Basically, the "MAIN" and "CRUISE" lights come on appropriately, but nothing actually happens. it doesn't hold a speed. this is a Series 5 non-turbo. i have checked the following (as instructed in FSM):

1) Self-diagnostic inspection (self-diagnosis of malfunction): There are no condition codes reported

2) Self-diagnostic inspection (quick inspection of cruise control system): all buttons and switches give the appropriate code

3) freeplay of actuator inner cable: i'm not entirely sure which part of the CC cable this was, but if it is the part at the throttle body, it is adjusted within spec.

4) actuator solenoid resistance: everything checks out fine with this


now the only thing i haven't really tested is the manual inspection with a volt meter, but if all the above things i have checked are ok, then what could it be?
is something messed up with the wiring? the previous owner may have tried to wire it up to work with an S4 CC switch, but if all the above check out fine, i don't think so.

any help is appreciated, thanks,

 

If I may ask, why do you want cruise control? unless you have an AT, cruise control + MT = even worst gas mileage.

 

Same reason everyone wants it, to be lazy.

 

yeah, pretty much. if it's already in the car, why not? i have to drive to work 40 minutes each way, and other long distances on highways, where there are cops every 10 minutes, so i have to try to keep a constant speed...i always end up speeding. plus my leg gets sore after 6 hours.

ANYWAYS, i went for a drive, and i checked error codes again, and for some reason this time i got one:
CODE 01: Defective wiring or ground, defective actuator, or defective stoplight switch.

well i have ruled out defective actuator and stoplight switch...so it must be a defective wiring or ground. the FSM says to "repair harness". great. i don't even know where to start with that...check every single connection i guess??

 

Check your grounds. Have you ever regrounded?

 

nope, i have not redone the grounds on the car, but i haven't noticed any problems so far with other systems.

well, the cruise harness is 17 wires total...so i have to troubleshoot now.

the FSM gives a test procedure for wiring faults, but it isn't simple...and i still have to figure out how to test the ECU connections WHILE the harness connector is plugged in

 

what are you basing even worse gas mileage on? i seem to notice i get the same, if not better mileage, on cruise.

and like i mentioned, that is not my main intention. my main intentions are not get caught carelessly speeding, and so that my leg doesn't cramp up after too many hours on the road.

 

i drove from orlando to chattanooga, TN and back once a month for 4 months in my 7 and got 27mpg using cruise (about 1200 miles round trip)... so i woulda gotten more if i didnt use it????

 

mine just messed up.....
i hit the button and get nuthin.....the lite is on in the switch but it wont work..