Originally Posted by thook

BTW, the TPS is merely a switch. Where the IDL circuit is concerned, it is just like a light switch. With a light switch, you have wires to the switch, then the switch, then the wires to the light fixture. If you're light bulb is flickering, you have to track down the problem within the circuit. Check the power supply. Say it's fine. You're getting 120v's from the breaker. Then, test the wires coming from the breaker where they connect to the switch terminals. Let's say all good. You're getting 120v's at the hot terminal. Now, test the output side of the switch. That would be the terminals where the wires going to the fixture would connected. Oops.....you're only getting 4v's intermittently. Somethings wrong with the switch. So, you're light's flickering. Something making poor contact.

Okay. With your sensor the IDL circuit is this switch. You can test for voltage, but the amount of resistance will suffice because it will tell you if the supplied voltage will even pass through the circuit properly.

With the light switch example, resistance should be zero as you don't want anything to compromise or impede the 120v's you need to be getting. The zero would indicate a closed circuit, meaning voltage can pass through. The light will turn on. If it read infinite, it would mean the circuit is broken, no contact between wiring and/or terminals is being made and voltage cannot pass. The light switch being turned off is a prime example. Contacts/circuit is broken. Light is off. Any amount of resistance value other than zero or infinite would mean there's damage to the wiring or terminal and the amount of voltage will be less than what's needed.

So back to the sensor, when the IDL switch is "on", or in range for a voltage signal to be relayed back to the ECU, it should read within the proper resistance indicating that the circuit is complete and the amount of voltage being relayed will also fall within spec/what the ECU is needing. Once the throttle plate opens, the IDL circuit/contact should break and indicate infinite. No voltage can pass. This means, to the ECU, the light is "off". Or, idle is off and throttle is open........which is where your VTA (throttle valve angle) becomes relevant.

So, when adjusting/setting the TPS, the resistance needs to be below 2.3k so that the ECU will receive a static reading of voltage (no more or less than what is needs....and, I forget how much it does need) indicating the engine/throttle is at idle. If the voltage is steady, the idle should be steady.........of course, provided nothing is wrong with anything else on the engine.

Anyway, hope that clarifies the subject for you a bit. If not, sorry. But, I try... If you have anymore questions, ask.