Low Coolant Sensor Schematic
I found this module in my dash right behind the fuse panel. It turned out to be the low coolant indicator module. The box was covered with sticky goo from being taped to the wiring harness and when I cleaned it up the part number that was rubber stamped on there got erased so I added the label.
http://www.misterpeachy.com/VettePic...Module_Top.JPG The back side: http://www.misterpeachy.com/VettePic...ule_Bottom.JPG This is an interesting circuit. U1-E & U1-F are an oscillator that operates at about 5 KHz. The circuit filters this out and applies it to the transistor, which turns on the low coolant indicator lamp. When the low coolant sensor is submerged it basically shorts out the output of the oscillator and turns off the transistor, so the low coolant lamp goes out. The 160K resistor and 10uF capacitor put in a delay of a couple of seconds, which keeps the lamp from blinking rapidly when the coolant is sloshing around the sensor. I think it's interesting that the coolant is the return line to ground for the one wire sensor. None of the components have mysterious GM part numbers, so it should be easy to repair this module. http://www.misterpeachy.com/VettePic..._Schematic.pdf |
How 'bout that !?!
First time to see this one. :cheers: |
2 Attachment(s)
Here is a schematic for the low coolant relay along with a photo of the board.
FWIW :thumbs: |
That's cool. I like the color coding. Did you draw that?
I didn't calculate the time constant. I just guessed based on what I saw happening on the scope. One thing I noticed: 100M is not a standard resistor value. They only go up to 20M. |
Originally Posted by Cliff Harris
(Post 1579590091)
That's cool. I like the color coding. Did you draw that?
I didn't calculate the time constant. I just guessed based on what I saw happening on the scope. One thing I noticed: 100M is not a standard resistor value. They only go up to 20M. I don't know about the resistor value. |
Check for gasses in the coolant. Blown head gasket will cause that.
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Originally Posted by kenmohr
(Post 1597006829)
Check for gasses in the coolant. Blown head gasket will cause that.
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Originally Posted by arbee
(Post 1597007502)
Will cause what????
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Originally Posted by arbee
(Post 1597007502)
Will cause what????
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Originally Posted by kenmohr
(Post 1597014358)
Blown head gasket.
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Originally Posted by arbee
(Post 1597015317)
What are you talking about? Besides being years old, this thread is about the electronic function and construction of the low coolant module. How does this in any way involve a blown head gasket?
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