Coolant temperature gauge

discussions specific to the 907IE
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paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Coolant temperature gauge

Post by Derek »

Well I pulled the dash apart and took out the coolant gauge. There's not much to it. A circuit board with one resistor and a coil of very fine wires inside. The tacho has to come out before you can extract the gauge because it's dial overlaps the coolant gauge.

As I said before with the ignition on the gauge was reading 175ºF with or without the sensor connected and I also found that with the 4-pin connector to the dash removed which carries the ground to the dash, the sensor connection, the charge warning light connection and the dash illumination that the needle moved up to around 110ºF with the ignition on, so it was finding a path to ground through something.
I also realized that since the scale starts at 105º there was no way I could set the needle properly as there is no zero position. If it started at 60ºF it would have been easy as that was about the ambient temperature yesterday and the sensor had a resistance of about 7KΩ
With 12v connected to the +ve terminal and ground to the negative terminal the needle, as expected, rose to 175º. Without some resistance representing the thermistor at running temperature of around 160ºF the best I could do was pull off the needle and put it back at the bottom of the scale at 105º.
While the dash was off I took the opportunity to clean all the flexible circuit connectors. What a stupid arrangement to use on a motorcycle where the elements can get it. The only connector to show signs of corrosion was that 4 pin one next to the coolant gauge.
So put the dash back together, connected everything up and turned on the ignition. Bugger! I had expected the gauge to stay at the bottom of the scale, it now reads about 140ºF. So an improvement in the right direction but still nowhere near right. Once I get some petrol in the bike I can get it warmed up and see what the new normal is.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)

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Posts: 319
Joined: Fri Nov 13, 2009 4:33 pm
model: 750 Paso
year: 1987
Location: San Francisco Bay, California USA

Re: Coolant temperature gauge

Post by randtcastell »

Mc tool wrote:my RC chopper battery must be recharged as soon as a drop of in power is noticed , if you run it near flat ( like trying to get it home ) its custard .

Sorry to get off topic, but I just had to interject that I'm an rc chopper nerd/fool. Micro and mini mostly 'cuz they're inexpensive. Love to fly 'em: challenging... I hate the damned lithium batteries. That hobby made me a good solderer and gave me decent servo knowledge. :^) Thank you for the bandwidth.
1987 Paso 750
1973 Honda CB450
2017 Kawasaki Ninja300 track bike
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