Throttle Full Close Switch: Description and Operation

Throttle Switches





CIS-E Motronic (engine code 9A) engines have idle and full throttle switches mounted either separately on the throttle valve housing, or in one housing under at the bottom of the housing. Some early CIS-E Motronic engines have only a single idle switch.





Each switch opens or closes the circuit depending on throttle position. The switch functions are checked by making continuity checks with an ohmmeter at the switch connector. Image above shows Volkswagen special tool no. VW 1501 (order no. TV1 501 000 24 ZEL) attached to the throttle switch connector in place of the normal wiring harness connector on a ClS-E engine. The test harness provides convenient test points, but the switches can be tested without it.





Check the idle switch by checking for continuity at connector terminals 1 and 2. The circuit should be closed when the throttle is at rest, switching open as the throttle is opened slightly. To precisely check or adjust the idle switch, open the throttle valve about half-way and slowly let it close. The idle switch should close, completing the circuit, when the gap between the throttle valve lever and its stop is 0.15 to 0.4 mm (.006 to .016 in.). Check the gap with a feeler gauge as shown in image above.