Was recently checking the TPS Sensor due to a Flat Spot my car has and the specs that we have say:
When the ECU 48 Terminal is closed, you should get a reading of 1 Volt.
When the ECU 48 terminal is open, you should get a reading of 4.5 Volts.
The reading i am receiving is the other way around.
On open i get 1 Volt and on closed i get 4.5 Volts.
Does anyone know what we are doing wrong or why our reading is reversed?
OK, first the TPS uses a 5 volt reference wire, an earth wire and a signal wire, most of the time the signal wire is the middle one.
Here is what you do - first take the negative lead from the Multi-meter, attach to the negative battery post.
Key On Engine Off, take the positive lead and back probe the TPS. You
may need a paper clip for this, choose one of the outside wires. Voltage should be about 5V or 0V depending on which wire you are testing. Do the same to the other outside wire, the readings should be reversed from each other.
Do you have different readings between the two? If you have about 5V on both you have a bad earth. If you have 0V or almost 0V on both you have + supply problems.
Now if both of those seem good on to the next step. Now move your paper clip to the centre wire, make sure it is down in there, sometimes it is hard to get it all the way in to get a good connection. Now attach your + lead to that wire, it should read about .5V to 1.0V, now slowly open the throtle to WOT, <b>watch your meter closely,</b> there should be a steady rise in voltage up to about 4.5V, if it looks like it may be losing voltage at some point, try it again to make sure. If it is then you will need a new TPS.
If your power and earths are good and you have no voltage from signal wire you will need a new TPS.
If all checks out then you might have wiring problems.
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