TPS volt check ... please help!!

Hey all quick question... I have 90 4.0 auto on the TPS there is two plugs a flat 3 and round 4. Both have three wires... a gray, blue, and black. Ok here is my question should you get the same reading on the plugs... ex both plugs should have the same reading when the throttle is closed, half and open throttle... thanks please help!!!!! Jay

This site has a good TPS check scroll down about half way

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

DownhomeMoto said:

Hey all quick question... I have 90 4.0 auto on the TPS there is two plugs a flat 3 and round 4. Both have three wires... a gray, blue, and black. Ok here is my question should you get the same reading on the plugs... ex both plugs should have the same reading when the throttle is closed, half and open throttle... thanks please help!!!!! Jay

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The square connector is for the tranny and *is usually the one adjusted*, the flat plug is for the ECU and is worth a look see (test).
You won't get the same reading on both as they work just the opposite of each other. The square connector (tranny half) of the TPS starts high (usually around 3.8 volts-4 volts) and the voltage lowers as the throttle is opened. The flat connector (ECU half) of the TPS starts out at a low voltage (0.8 volts is ideal but not a fixed number) and the voltage reading goes up as the throttle is opened.

Thanks for the link XJ Stryker, but I already have that link and it only talks about one connector and it doesn't say which one.

8Mud... Ok on my flat 3 it starts at about .5 volts with throttle closed and then moves up to 4.7 volts at WOT. And the four pin starts at .8 volts and it has not changed at all.

I know grounds are a problem and I have made grounding wires from the harness to the block. I also have a good ground from block to firewall. Thanks for yor input guys BUT NEED MORE!!!!! hahaha the hunt continues....DH

On the square connector there are small markings (A,B,C,D). "D" is the black wire and should be the ground. "A" is the power in and is typically 4.6-4.8 volts (they call it the 5 volt supply). "C" is the out volts and is typically 3.8-4.0 with the throttle closed. If you want to be exact, you multiply the voltage at "A" by .83 the results are often 3.8 volts. All tests are done with the connector connected and the key in the run position. Back pinning the connector can be a pain and is often more problem than solution. Run your TPS wires over the top of the rubber elbow for the throttle body and make a quarter inch cut lengthwise on the three wires, I use an exacto knife. Being careful to cut through the insulation, but not to damage the copper wires. When your done you can cover the cut over with a drop of silicon gasket sealer (and remove it next time with your thumb nail).
You can get anal with the whole operation, but In my experience there is no exact.
The Renix files has a lot of good info on further tests for the TPS and experiences from a bunch of guys who have been there and done that many times.
Harness, connector and grounds cause problems as least as often as an actual bad TPS does.
You are a actually adjusting the TCU (transmission controller) and hoping the ECU half of the TPS is near enoguh to work properly.
What are your issues with the TPS? Motor, transmission?

If there is any question about the sensor Ive found that its cheap enough to replace if the sensor is as ancient as the vehicle itself. I replaced mine even though it didnt need to be and the truck runs better. Just be careful not to strip out the head of one of the mounting screws. They virtually dont exsist unless you buy a new sensor from the dealer.

The Lure Washer said:

If there is any question about the sensor Ive found that its cheap enough to replace if the sensor is as ancient as the vehicle itself. I replaced mine even though it didnt need to be and the truck runs better. Just be careful not to strip out the head of one of the mounting screws. They virtually dont exsist unless you buy a new sensor from the dealer.

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yeah man, mine are stripped and it suuuuucks!