mjwalfredo

Hey... I am trying to get a quick answer here.

My TPS only has 3 pins, VTA. VC and E2. The FSM I have that lists the detailed resistance settings has measurments using the IDL pin, which doesn't exist on my TPS.

The other FSM I have (both are from ttora.com) shows the test with my 3 pin TPS but it doesn't show the detailed resistance readings. It only shows fully closed, fully open and VC - E2 at any setting.

Is my TPS not adjustable? Can anyone tell me how to test this thing correctly? Please help a confuse DIYer. Thanks!

97ltd4x4

Vc= voltage constant,should be 5 volts
E2= earth,ground
VTA=Varing voltage,sweeping varing resistance(butterfly is attached to)

mjwalfredo

So should the resistance rise linearly on the VTA pin as I open the throttle body? Is it supposed to jump to infinity as it transitions from idle to open throttle?

Thanks 97ltd, you have been a big help.

97ltd4x4

It is a linear sweeping sensor,But don't be fooled whith a OHMs check and meter settings..I just checked the FSM and they specify .28kOhm-6.4kOhm at closed position w/vacuum applied to throttle opener,VTA-E2 2.0-11.6kohm(open throttle),and 2.7kOhm-7.7 kohm resistance....These are huge ranges and its hard to tell if its bad or out of range,because the range is huge....The FSM is just trying to tell you how to test a TPS that is totally open..

First off,if you are testing the TPS with OHMs..You need to set the meter at K ohm setting..If not it will look like it goes open from .2k-6k in AUTO-RANGING on the meter as you move the TPS off idle....No autoranging

The best way is to see it is isolating w/ scanner only looking at TPS,then sweeping it....One other way is Voltage drop(this is how the computer sees the sensor,not OHMS).

The ECM reads voltage from The TPS..Roughly 4.0 volts at idle,1.0volts at open throttle(i may have it switched..I am rusty)...The ECM calculates this as a percent for the scanner port....

So. with out a scanner,the most accurate way to test the TPS is by doing a voltage drop,Key "on",connector connected,back probe wires I like using "T-pins"(can find at walmart-crafts store)...Make sure they do not touch eachother........or if you have long shrp enough test leads,you are good to go...

Set meter on Vdc,back probe Tps wires Vc-VTA,key "on",apply vacuum to throttle kicker diaphram to take pressure off throttle butterfly..Move throttle slowly..If now you see open-out of range on voltage scale,Or you might see 4 then 3 then back to4 volts..anything funny like that..The voltage should either rise or fall going in a direction......If not.....There is your bad spot on the TPS.....

The actuall voltage running through the circuit will pick-up better on a meter doing a voltage drop test....Because doing an OHm's check...the meter just puts a very low level amount of voltage,then the meter calculates the OHMs...Its better to test the actual voltage of how the ECM sees the signal.then OHMS.

You know if you are in doubt,you can just replace it with a new one..I do not think they are very expensive,plus they can go bad anyway....If you do,get a IAC O-ring and clean that IAC really good,while you are there

mjwalfredo

I really appreciate the detailed information 97ltd, I find this stuff interesting to me and I feel like it would be useful in the future. But today, I think I am going to take your last bit of advice. It's $50 bucks for a new sensor, so it's not going to break the bank. I am pretty sure it is shot because I heard that if too much carb cleaner gets on it, it can go bad. I bet that happened the first time I cleaned my throttle body because I dueched the thing with carb cleaner. I had no idea it was bad for the sensor at the time.