HAL 1
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| posted on 31/12/07 at 12:19 PM |
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testing speedo sensor
hi, my electronic speedo stopped working a while back, just went haywire and then nothing, at the speedo itself i've got power/earth/dash light
and sensor wire going in, all ok except sensor wire, question is how do i test that wire? been told a circuit test wont do it.
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BenB
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| posted on 31/12/07 at 01:39 PM |
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I'd suspect the sensor and it's wiring then 
You can check for continuity between the sensor signal and where that wire attaches to the dial. The only real way of testing for a signal is with an
oscilloscope. The speedo sensors often have coils in them that don't like being clouted, if the trigger wheel or magnets have been making
contact with the sensor they fail... A loose connection could also do this (the vibrating wire would initially cause a haywire signal as you
describe).
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tks
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| posted on 31/12/07 at 03:39 PM |
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it depens on the type of sensor tought...
if its a reed sensor it will work when you put it close to a magnet (stays open/clos)
if its with coils its hard to test it.
if its inductive you can test it stationairy..
Tks
The above comments are always meant to be from the above persons perspective.
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HAL 1
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| posted on 31/12/07 at 05:51 PM |
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thanks guys
looks like a new sender then, the only
problem the is how to stop vibration?
I had sender mounted on chassis picking up signal from propshaft bolts, cap head so distance was uniform, Sierra diff also mounted in chassis !
I had thought it had been hit by bolts, perhaps just grazed and damaged it. basically more outlay!!
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