Bosch Motronic - Component Datasheet
Throttle Valve Potentiometer (G69) with Idle Switch (F60)
These two devices are combined into one physical
component that bolts onto the inlet manifold near the throttle body. The
Motronic ECU on the S2 does NOT have use a wide open throttle (WOT) switch
unlike many previous turbo engines from Audi.
The purpose of the potentiometer (G69) is to determine the angle at which the throttle plate is opened. This parameter is directly proportional to how far the loud pedal is being pressed. This information is used for boost regulation such that the ECU looks up a map to determine how much load is being 'requested' by the driver. This regulation function only comes into effect when the throttle plate is open greater than 35 degrees. Should G69 fail, or be disconnected, the function of boost pressure regulation falls to the mechanical nature of the wastegate which is set to relieve boost pressure at lower levels than what the ECU is programmed for.
The function of the idle switch (F60) is to tell the ECU when the throttle plate is in the closed position. The idle switch closes approximately 1.3 degrees before the actual throttle plate closes. When the ECU detects that F60 is closed it engages the following functions as per the conditions require :
Should the idle switch fail the idle stabiliser
and other functions above will be inoperative.
Testing the closed throttle position (CTP) switch, F60
A digital multimeter (DMM) is needed to quickly test F60 in isolation. With the engine OFF, disconnect the wiring connector at the throttle position sensor. A six pin connector is exposed on the component body. Taking Pin#1 as the TOP, simply measure the resistance between pins #4 (four) and #6 (six).
At idle the switch is closed so resistance = 0 ohms (or as near as possible).
When the throttle pedal is very gently pressed off the idle position, resistance should be infinite (o/c).
If these values are not measured the body of the sensor can be adjusted to correct matters. If that is unsuccesful the throttle position switch/sensor should be replaced.
Testing the throttle position sensor (TPS), G69
This can also be readily checked with a DMM whilst the connector harness is removed. There are three stages to this test sequence :
1. Checking voltage from ECU on harness with Ignition ON (Engine OFF) - With the DMM set to measure DC VOLTAGE, place the probes onto pins #1 (one) and #2 (two) of the wiring HARNESS that connects to the throttle sensor. A value of 5V +/- 0.5V should be measured. The same voltage should be seen with the probes on pins #2 (two) and #3 (three).
2. Changing the DMM over to measure RESISTANCE, the focus now turns to the pins on the component. With the throttle in the idle position a value of 1500-2600 ohms should be measured across pins #1 (one) and #2 (two). Keeping the throttle on idle, the resitance seen across pins #2 (two) and #3 (three) of G69 should be 750-1300 ohms.
3. Keeping the DMM set to measure resistance across pins #2 (two) and #3 (three), the position of the throttle should be gradually moved towards full open and the observed resistance should increase SMOOTHLY to approx 3600 ohms on wide open throttle. If jerky and irregular readings are observed then the potentiometer is internally damaged and will provide a confusing signal into the ECU.
If any one of these tests fails then the throttle sensor (G69/F60) should be replaced.
Follow this link to related TPS info on SJM's site.
Last Updated 9th November 2007