When the Air Bag light turns on it means the computer detected a problem, set a diagnostic fault code, turned the system off, and turned the light on to tell you. Your mechanic will read the code(s). Those will indicate the circuit or system that needs further diagnosis. The most common cause is a broken clock spring. That is a wound-up ribbon cable in a plastic housing under the steering wheel. As it continues to break, the horn and cruise control will also stop working. The fault code description for that is "Open squib" or "Open initiator circuit".
Is the brake light red or yellow?
The throttle position sensor has no affect on engine speed, and they have a very low failure rate. A vacuum leak will cause high idle speed, but if it's intermittent, the Engine Computer is usually commanding the higher speed in response to something. You need a scanner to view live data to see if the computer is requesting the higher speed or if it is trying to lower engine speed without success.
Thursday, September 19th, 2013 AT 11:32 PM