View Full Version : Fast idle and ASR light on !

09-17-2013, 06:07 PM
I have an intermittent fast idle, about 1200 - 1500 RPM with the ASR light on.
Not sure if it is the throttle actuator OR the throttle body potentiometer.
Car is a 91 500SL.
How do I test the actuator and/or the throttle body?
Doesn't go into limp home mode.
Just that the idle stays high, which is dangerous when trying to roll to a stop or reverse, and the ASR light is on.
Any ideas.....

09-17-2013, 08:18 PM
That's a KE-Jetronic car, so it doesn't have an ETA like our 500E/E500s do.

Fast idle on a KE car is usually a symptom of a vacuum leak. You need to consult the factory manuals.The throttle body has a position switch, but it is not electronically controlled (drive by wire).

You need to pull codes and clear them, first.