I want to test the voltage on my throttle sensor, I have a multi meter but I am unsure how to go about it. Can any of you offer some tips?
I know the voltages I have to look for but how do I get into the connections to get the voltages?

 

I have a little harness that plugs into the TPS and the factory Connector at the other end. It has a spare pair of wires that you connect the meter to and then adjust the TPS to the right voltage. The harness complete the circuit but allows me to see the voltage it was set to. If you don't want to do that you can push a straight pin thru each wire and measure the voltage that way I would think. When done carefully wrap the area with the pin hole with Good quality electrical tape so water doesn't get in.

Many years ago I bought a kit of C4 Setup harness' from Mid-America. Each one is a little harness that allows you to easily set up the throttle body and verify that the other components are working properly. The set was about $75 and it has been very handy. It came with a TPS setup harness amongst others. I also checks the O2, the MAF and five other important components. The harness has little alligator clamps to attach to your meter.

I just got the box of test harness'. They come with a harness for the Throttle Position Sensor, Idle Air Control, Coolant Temperature Sensor, Knock sensor, Oxygen sensor, Manifold Air Temp and Mass Air Flow sensor's. This is how I learned that my knock sensor was bad.

The one for the TPS has three wires Purple (blue?) Red and Black. You want to measure between the Red and Black wire of the three wire harness to get the output of the TPS. The harness I have is a male three position weather proof connector and a Female three wire connector. There are extra wires coming from the Red and Black wires that go to your multi meter. So ignore the purple or blue wire and just use the other two, I apologize as I am Color Blind and it looks purple to me.

I hope that this helps a bit!

 

You can get something like this: https://www.corvetteforum.com/forums...post1602911017
...or just back probe the connector.

 

I made some probes for this using a couple small alligator clips and a couple long needles from my wife's sewing stuff. Soldered the needles to the alligator clips where the wire would attach. The pins allow me to back probe the TPS connector.
Then I just clamp the alligator to my multimeter leads.
Went

 

What are the voltages? I thought I read that the 89' and about doesn't need to be adjusted? If so is it 5.4? and what would you put ur multimeter on to?

 

It absolutely needs to be adjusted on the '89. After the TPS is installed, you measure the voltage across the top two wires/conductors. It should be .540 volt with the throttle plate closed at idle. Loosen the screws / move the sensor until you get as close to that reading as you can, tightening the two mounting screws at that position. Make sure that you don't let those two conductors / alligator clips touch when you're testing the sensor, keep them separated so they don't touch.

 

I made a video on how to make one, here it is:

 

Currently doing the same thing myself. Should the TPS be set with the car running or not?

 

Ignition on but engine not running.

 

Thanks!