Chrysler Repair: cruise control dodge neon 1995, powertrain control module, vacuum servo

Question
What are the common causes for failure?

My cruise control just stopped working one day.

Also, do you have a schematic on the cruise control system?

Answer
Hi Maurice,
I don't have a manual for the Neon but most of the Chrysler cars are set up similarly. The main items that need to be verified are the fuse of the speed control system, the vacuum line from the intake manifold to the vacuum servo unit (usually under the battery or there abouts (trace the cruise throttle cable to its source to find the servo)) should be checked for leaks at its connections or cranks anywhere along its length, the brake light switch which must be working correctly for the brake lights themselves and also must not be being activated when not is use due to the pedal mechanism slightly depressing the switch (check for switch adjustment and normal brake light function), and finally the cable from the servo to the throttle for good connection. If your speedo unit is not functionning or is intermittant that too would compromise the control function.
Those are the most common sources for non-function. The wiring of the circuit, the powertrain control module, and the servo all could be defective but that is less likely.
So do the common checks and let me know if that doesn't fix it. The most common wiring problem is the clockspring unit in the steering wheel which provides for a flexible connection between the wheel and the rest of the speed control system. I can send you a diagram from the '93-97 Haynes manual for the LHS sedan as a sample in case you need to trace the circuit to find a break somewhere. Just give me a postal address.
Roland