Adjusting and Cleaning the Throttle Position Sensor

Author: Trevor R. Sheffield

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In order to adjust the TPS, the manual says to measure voltage at the TPS by inserting meter probes into the plug at the ECU. Nice and easy that is! In order to accomplish the feat without tying yourself in a knot you will require, best of all, one of those dress making pins with a nice thin shank and a knob on the end, or a thin needle. Also a meter to measure 0.5 volts D.C..

The TPS comprises a potentiometer, presumably used in a voltage divider configuration, as three wires come from it. There is a plug and socket close to the unit so that it can be easily removed for servicing. At this plug, the wires are --- black ground and one end of the resistance element, red the other end and white the wiping contact.

Stick your pin right through the white insulated wire so that you can clip your meter lead onto it to make measurements. A fine pin will not damage the conductors as they will spread and there will be no significant damage to the insulation. Measure between the wiper, i.e. white wire and ground, by connecting to engine, chassis, battery negative, or whatever.

Now from the book:

  1. Connect all connectors.
  2. Loosen TPS fixing screws.
  3. Turn ignition on.
  4. Adjust TPS position while throttle valve is FULLY closed, using a volt meter, to the specified voltage.
  5. Tighten fixing screws.

The voltage is specified within a tolerance from 0.45 to 0.55 volts. You should have no trouble in setting things at exactly half a volt. (0.50)

Before removing the TPS or altering the original setting, it is a good idea to mark the mating castings with a scratch so that one can check on the adjustment, before and after, as a matter of interest. It is always nice to know if the effort expended has in fact improved things.


After removal the unit, it is easily checked with an ohm meter for smooth operation or otherwise. Even without dismantling the unit, a spray with CRC or similar cleaner and a work out will do wonders. The resistance end to end (black to red) should measure very close to 5000 ohms. Measuring between white and red or black should show a smooooooth change in resistance when moving the control shaft over full distance.

If you remove the unit, stick the pin in before replacing it, as it is much easier to do on the bench. Don't forget to pull it out when you have done the deed.

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