Low Sump Oil Warning sensor dismantled
Posted: Wed Feb 19, 2014 6:10 pm
Low Sump Oil Warning sensor dismantled.
Having found half of the Sump Low Oil Sensor's float lying in the sump, see Photo 1, I removed the unit. The purpose of the float was to move a ring magnet embedded in it up and down on the plastic sleeve on the thinner vertical brass tube on the right of Photo 2. Believing that the purpose was to turn off and on a tiny magnetic switch sealed in a hermetic glass tube installed in the tube, I physically moved the magnet up and down while measuring the resistance between the 'live' terminal and the chassis. Nothing changed --- there was a permanent short circuit between the two!
So I ground off the top of the central rivet (which has a dome on its bottom) which holds the assembly together and unsoldered the wires at each end of both vertical tubes. But that was not enough, for each vertical tube had a brass plate sealing its end --- so I removed those too.
The result is Photo 2. The R H tube did in fact have a tiny magnetic switch, but this had now been destroyed --- all that remains is a short piece of iron wire, half of the switch, with some glass on it. I removed more glass with a 2.6 mm drill, the largest that would fit into the tube.
Then came a surprise: the central part of the larger 'brass' tube on the left turned out to be a brass-coloured insulator which has brass plates on each end. The wire running through its centre (so accounting for the permanent d.c. short circuit), has on it two ring magnets and what looks like a ferrite bead but may be a capacitor. Now it seems that the sensor unit probably operates on a.c. from the vehicle's computer! How short-sighted to have destroyed it!!
Photo 1: Broken piece of float
Photo 2: Dismembered sensor unit
Having found half of the Sump Low Oil Sensor's float lying in the sump, see Photo 1, I removed the unit. The purpose of the float was to move a ring magnet embedded in it up and down on the plastic sleeve on the thinner vertical brass tube on the right of Photo 2. Believing that the purpose was to turn off and on a tiny magnetic switch sealed in a hermetic glass tube installed in the tube, I physically moved the magnet up and down while measuring the resistance between the 'live' terminal and the chassis. Nothing changed --- there was a permanent short circuit between the two!
So I ground off the top of the central rivet (which has a dome on its bottom) which holds the assembly together and unsoldered the wires at each end of both vertical tubes. But that was not enough, for each vertical tube had a brass plate sealing its end --- so I removed those too.
The result is Photo 2. The R H tube did in fact have a tiny magnetic switch, but this had now been destroyed --- all that remains is a short piece of iron wire, half of the switch, with some glass on it. I removed more glass with a 2.6 mm drill, the largest that would fit into the tube.
Then came a surprise: the central part of the larger 'brass' tube on the left turned out to be a brass-coloured insulator which has brass plates on each end. The wire running through its centre (so accounting for the permanent d.c. short circuit), has on it two ring magnets and what looks like a ferrite bead but may be a capacitor. Now it seems that the sensor unit probably operates on a.c. from the vehicle's computer! How short-sighted to have destroyed it!!
Photo 1: Broken piece of float
Photo 2: Dismembered sensor unit
