This switch (PN 078 133 154) is attached to the shaft at the end of the throttle body (item 4 in this image:)

The switch tells the ECU what you are doing with your right foot, i.e. what the position of the throttle is at, it might even allow the ECU to check the speed at which you opened the throttle. The idle switch has two positions,idle and Wide Open Throttle (you can hear the microswitches click when you move the throttle body by hand with the engine off).


If the potentiometer or idle/WOT portions of this switch fail, then the ECU will be unable to control your engine as you would like it to, i.e. the ECU will ignore your right foot demands. You will need to replace the switch. This switch is very common across the mid 1990's Audi's including the 12V V6 engines so a used one should be easy to find.

Be aware that the six pin connector is similar to the MAF connector and as such, subject to the same problems, e.g. a female (harness) pin getting pushed back into the connector, not making contact with a male pin in the powered device, in this case, the throttle/idle switch, as shown here (Pin 4, third from the left is pushed back too far):


Photo courtesy of GreenMachine (Brad L)

The pin-out on this connector (Based on Pg. X56 in Vol.3 of the Bentley) is as follows:

Pin 1: A red wire that also connects to T12/55 in the ECU which provides 5V+ to the G69/F60 combination as well as the F96 Barometric Pressure Sensor and the G40 Cam Position sensor. (Note: The Bentley incorrectly calls the Pressure Sensor the "G16" but there is no such "G16" device for the AAN).

Pin 2: Green wire with a Black stripe - goes to ground connection 5 in the engine harness.

Pin 3: Gray wire connected to pin T53/55 in the ECU - the signal is the 5V+ modified by the variable resistor in the throttle position switch which tells the ECU the degree to which the throttle body is open, which helps the ECU compute "load".

Pin 4: Brown wire with a red stripe, goes to ground connection 2 in the engine harness.

Pin 5 - not used

Pin 6 - Violet (purple) wire that connects to pin T52/55 in the ECU that tells the ECU that the throttle is closed (via the microswitch in the diagram shown above).

This will be on the exam