Check the throttle valve switch
Check the throttle valve switch for correct mounting
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Throttle valve switch: Function, fault symptoms and testing instructions
The throttle valve switch informs the engine control unit about the throttle valve position so that the mixture and ignition can be adjusted to suit the respective load. This page explains how the throttle valve switch works and how a fault impacts the running of the engine. You will also find practical tips on how to check the throttle valve switch.
How the throttle switch works
Checking the throttle valve switch
1
2
Check the switching mechanism
Check whether the switching mechanism is actuated by the throttle valve shaft (with the engine switched off, move the throttle valve from the idle limit stop to the full-load limit stop and listen to hear whether the switches are actuated)
3
Check the plug connection
Check the plug connection to ensure it is fitted correctly and for any contamination
4
Check the switch contacts using a multimeter Pin assignment
- Idle switch closed: Measurement between pin 1 and 3. Measured value = >30 MOhm.
- Idle switch opened: Measurement between pin 1 and 3 (Caution: Slowly open the throttle valve during the measurement until the idle switch opens). Measured value = 0 ohms.
- Full-load switch opened: Measurement between pin 1 and 2. Measured value = >30 MOhm.
- Full-load switch closed: Measurement between pin 1 and 2. Measured value = 0 ohms
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