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Old 05-05-2013, 07:53 AM
bygddy bygddy is offline
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Originally Posted by 75gmck25 View Post
Get a VOM (Walmart has some for about $10) and start checking the resistance and continuity.

- With the sensor installed, check resistance between the sensor body and a good ground on the engine block. It should be zero. If not, then you need to ground the sensor and/or the head to the engine. This verifies that the sensor is properly grounded.

- With the sensor installed, check the resistance between the sensor terminal and engine ground. From what I recall, it should be 0 ohms with a cold engine, and rise to 90 ohms at the max scale. If it changes with temperature as the engine warms up, then the basic sensor operation is good (although sensor/gauge calibration may still not match).

- Disconnect the sensor wire and with the ignition on:
-- Verify that you have 12 volts on the sensor wire when the ignition is on.
-- Put a 10 or 20 ohm resistor from Radio Shack between the wire and engine ground. You should get a low gauge reading.
-- Then try the same thing with a 90 ohm resistor and you should get a high reading.

If it passes all the above tests its basic functions are working; however, if the gauge itself is off calibration or the sensor has the wrong resistance range (e.g. Fords are different) then you may still be getting readings that are off.

Thanks for the guidance Bruce, will give that a try today
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