Outside Air Temp Sending Unit - Printable Version
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+--- Thread: Outside Air Temp Sending Unit (/showthread.php?tid=5620)
Outside Air Temp Sending Unit - Jackflash - 08-18-2020
I've searched every way I can think of and find info on just about every gauge and sending unit on the coach except the outside air temp gauge above the driver's seat. The gauge died and upon replacing it the new gauge lights up but displays "000". I have tried every wiring configuration available since the new gauge had one wire that was color coded differently. At this point I am assuming it was designed for a different type of sending unit (a new one came with the gauge) but I can't seem to locate the existing one to replace it. Does anyone have a clue as to where it's mounted? I've looked in the bay under the driver's seat and under the coach where the six pack is, no luck so far.
RE: Outside Air Temp Sending Unit - Mhcorrigan - 08-18-2020
Mine is located on drivers side front lower outside where it is exposed to ambient air. Thing doesn’t read correctly after Newell changed it and they told me there is no way to calibrate it. I just ignore it.
RE: Outside Air Temp Sending Unit - Jackflash - 08-18-2020
Found the sensor but it only had a 2 wire lead, one hot and the other a ground I guess. not sure how a signal got transmitted back to the gauge unless it was a voltage drop thing. The new sensor requires a hot, neutral and signal wire. I will have to find a way to snake another wire down to the front corner.
RE: Outside Air Temp Sending Unit - encantotom - 08-18-2020
hi jack,
i dont understand what you are saying. the temp gauges are not 120v so do not have neutrals.
tom
RE: Outside Air Temp Sending Unit - Jackflash - 08-18-2020
Wrong term, should have said ground not neutral. DC has to got to go to ground at some point.
RE: Outside Air Temp Sending Unit - bestgenman - 08-18-2020
A short primer on gauges, not all but most used. The gauge is really a voltmeter so a +12, a negative, and a sense connect to the gauge. The negative could even be eliminated but used to drive a digital display or a backlight on an analog gauge. The sense is a resistor to ground I.e. oil pressure is a variable resistor modulated by pressure, a temperature sender uses a device that changes resistance as the temperature changes. They can be direct or indirect. That means the gauge could go full scale if the sender has 0 resistance as in direct or could drive the gauge to zero with zero resistance.
Example: I had a new fuel tank built and the old sender didn’t work so I bought a new one the correct length , not paying any attention to the direct or indirect. Installed the tank and walla, no fuel showing on the gauge. At this point , I was sure I had forgot to remove the shipping pin and there isn’t enough room to extract the sender. I decided to go back to the log book method, disappointedly giving up on the gauge. Did a 600 mile trip and noticed the gauge was about half tank. It then dawned on my thick old mind that the sender was not matched to the gauge as full on the gauge is an empty tank?.
So, your temp sender is a resistor to ground, I would bet, and you could use the new sender replacing the old one. The sense wire can be grounded driving the gauge to max low or high to determine if the wire is intact