Testing the TPS

[Trevor]

As a result of another thread involving a faulty throttle position sensor, a possible handy man method of reliable fault finding has come to mind, but experimentation is required.

As many will be aware the TPS comprises a potentiometer consisting off a conductive plastic resistive element around which traverses a wiping contact. Dirt on the surface can interrupt contact, as can a faulty element or inadequate pressure on the contact. It can be difficult to detect intermittent contact as the wiper is turned, due there being little time to register a measurement as the wiper passes over a faulty area. The response time of a typical ohmmeter or voltmeter is inadequate. A meter with a bar graph or an oscilloscope is required. The handyman does not normally have access to this sort of gear.

Most will have been annoyed by audio gear which has a noisy volume control. Has the penny dropped ?????!!!!!

Hook up the TPS with a capacitor of a few mfds in series with a torch cell and stick the output across the input of an audio amplifier. There are three connections to the TPS, which appears to used in a voltage divider configeration. Terminals 1 and 3, (4k 0hms) should be connected across the amp. input and 1 and 2 or 2 and 3, to the capacitor in series with the torch cell. Anything will do, guitar amp, walkman add on, whatever. In fact high impedance headphones should work. Turn the TPS and listen to the music ?! A nice rushing sound as the unit is turned will be good music. Nasty static will be bad news.

This is simply an idea at this stage and requires experiment by a keen member who has a TPS on hand. I feel that the effort would be worthwhile. Any takers ?.