'86, 190e, 8v, throttle valve switch

[kjsabat]

How to test throttle valve switch and what the correct Ohm
values should be?

[pentoman]

The switch on the thottle simply goes from 'open' to 'closed' i.e. 0 ohms to infinity ohms.

Another way to test it and its connection (thus eliminating more options) is this, it only works on an auto:



Drive at 30mph in '3', and shift from '3' to '2' with your foot off the accelerator. If it bangs down into 2nd gear with a jolt, your switch is working OK for zero throttle. If you do the same thing with even a tiny bit of throttle, it should slip quite a bit, letting you rev the engine fairly freely, and not instantly engage 2nd gear with a thump.

If you can get these 2 different behaviours, the switch is fine.


Why the switch causes this different transmission behaviour I don't know, as its primary function is to shut off fuel to the engine when you are coasting.

good luck

Russ

[sbourg]

The throttle valve switch is actually two switches in one package. One closes its contacts at idle, the other at full throttle. They report these states to the Fuel injection computer. If the idle switch closes, but the engine speed is above idle, the ECU causes the EHA to drop the fuel pressure below injector cutoff. Once the engine speed drops to the preset idle, the idle air valve circuit will take over loop control. The full throttle switch tells the ECU to provide full-load enrichment.