speed control servo keeps humming

[Kf6cmp]

I have a '03 and the speed control servo makes a humming sound and continues to hum no matter what. It used to make that sound just when starting the engine and would stop right away. now it just hums. also my cruise control stopped working. Is the speed control servo faulty? Thanks.

 

[rscurtis]

You may be hearing the vacuum pump running. It is located on the passenger side of the engine compartment near the PCM. Most likely, there is a vacuum leak in the CC plumbing which will cause the pump to run constantly. Disconnect the pump until you find the leak.

 

[CPittman]

I think the '03 and the early '04 use an "aquarium pump" mounted on the passenger side inner fender to pull the vacuum needed to run the cruise control. Chances are VERY high that you have a leak in the hard plastic hose that runs from the pump to the cruise modulator. Carefully feel along the entire length of the hard plastic hose and my guess is you'll find a spot where the hose has been rubbing on something and has rubbed a hole in the tubing.



The pump, unable to set a vacuum because of the hole, runs and runs and runs. It will eventually kill the pump (anywhere from $150 to $220 for a new one) because it is running constantly.



The fix is easy. Where you find a hole (there may be several) just cut the hard plastic line in two and slip a 2" length of regular fuel hose (or something similar) over the hard plastic line as a splice patch. Use zip-ties to pull the hard plastic line away from other areas where it may be rubbing.



Fire it up and she's good as new.

 

[Kf6cmp]

thanks for the info. I unplugged the pump and am in the process of finding the leak. Its odd how the pump runs the cruise control. my 99 doesnt but the 03 cruise c. does function smoother!