Dumb wiring question, RGS

Ventodue

Ventodue

Hero member
Location
France
Hi peeps,

Can someone please explain to me how the wiring of the temperature switch on my Corsa is meant to work?

Here?s the relevant bit of the wiring diagram.  I've hi-lighted the violet wire that goes between the switch and the terminal block that is next to the rev counter.  And the gauge in the instrument panel is, unsurprisingly, connected to the other side of this terminal block.

ulGp3v2T.jpg


I assume that the switch goes to ground as/when the temperature rises.

So where does the power for the circuit come from?

What am I missing/failing to understand here?  :-[ :-[  Gotta be something blindingly obvious ...  :o :D

TIA

Craig

(The other connections at the terminal block are the indicator idiot light; the full beam idiot light; the rev counter feed from the coil).
 
The temp 'switch' you refer to is a thermistor...it's resistance changes with temp.  It's supplied with 12v from the lighting circuit in the instrument console, and earthed by virtue of being screwed into the crankcase.  As the resistance changes, the temp gauge displays the result.  Because the oil temp sensor is fitted at the back of the crankcase, the oil is never really warm enough to give much of a reading at all - unless thrashed, as Sir Sid notes!  :D 
 
Rob said:
It's supplied with 12v from the lighting circuit in the instrument console <snip>
Click to expand...

Thanks Rob.  That's what I wanted to know.  I will pursue my investigations further.

Cheers

Craig

(P.s  I'm aware it's a superfluous piece of kit, but thanks to everyone for pointing it out.  I just like things to work, even if they serve no purpose.)
 
I was riding a borrowed SFC1000 in Paris a few years ago (Amicale meeting) and it was a very hot day and very gridlocked Paris, the oil temp gauge was reading mid scale, when I decided to stop and park on a pavement side walk, at the same time, everyone in front and behind me (about 20 bikes) did the same, some spilled fluids under the starter motor was boiling. A few blokes said their bikes had started smoking from the tail pipes.
CLEM
 
If you want to check your temperature gauge is working correctly, you can replace the oil dip-stick with an RR-Temperature gauge dip stick and compare it to the one on your dash.

my 1000 SFC's oil temp gauge also shows barely more than 60?C, but I know that it must read at least 20 - 25? higher...
 
Ventodue said:
Thanks Rob.  That's what I wanted to know.  I will pursue my investigations further.

Cheers

Craig

(P.s  I'm aware it's a superfluous piece of kit, but thanks to everyone for pointing it out.  I just like things to work, even if they serve no purpose.)
Click to expand...

Craig,

I don't regard it as superfluous at all.  Don't take the shown values for real ( I'd wager they are at least 20? lower than what's really going on), but as an indicator for the engine getting a bit hot under its collar.  Once the needle leaves its lower resting point, things are heating up.  Should happen all the time when riding around the south of France in summer, rarely happens up here...

The temp. guage ist the same sort of estimation instrument as the fuel guage. :D

piet
 
As Rob mentioned, the sensor is a thermistor that changes resistance with temperature. It actually reduces its resistance as it gets hotter. If you wanted it to be more sensitive (start registering at a lower temperature so you get an earlier warning) you could fit an additional resistor in parallel with the sensor.  The value of the bridging resistor will depend on the resistance curve of the sensor. I'd suggest you measure the cold resistance of the sensor and use a parallel resistor of about the same value or a little more. It won't have much affect on the hot end of the temperature gauge but will bring the cooler end into range.
 
Dellortoman said:
As Rob mentioned, the sensor is a thermistor that changes resistance with temperature. It actually reduces its resistance as it gets hotter.
Click to expand...

Therefore, if there's a partial fracture in the wire, the reading will show higher than it actually is.
Even if the wire shows continuity, the reading will still be way out. The only way to test the wire is via ohms, seen this happen where there is a regular moving section ie: At headstock area.
So check ohms with bars at full, middle, and opposite lock.
 
sfcpiet said:
I don't regard it as superfluous at all.
Click to expand...
Rats, Piet!  That means I am gonna have to get it working again!  ;)

(I'm currently getting no power down the violet wire to the switch - or 'thermistor', as I should properly call it.  Thanks to Rob, and after some poking around with a meter, I think I now understand how it should be being livened up.  But more investigations needed ...)

sfcpiet said:
Once the needle leaves its lower resting point, things are heating up.  Should happen all the time when riding around the south of France in summer ..
Click to expand...
Yeah, to be fair,  the fact that it has stopped moving at all is what originally alerted me that something weren't right ...

So when are you gonna be moving south, then?  :-*
 
Ventodue said:
Rats, Piet!  That means I am gonna have to get it working again!  ;)
Click to expand...

Now done  :).  Rather came back to life all of its own, before I could work out just what had caused it to stop.  Bit of corrosion, most like ...

P.s.  Just for the record.  As Rob said, the switch (thermistor) picks up its feed from out of the instrument panel.  In turn, the instrument panel is fed by the black wire that comes from fuse no. 2, via the horns and the front brake light switch (ignore the brown, orange and grey circuits below).

dp0UFgPr.jpg
 
chrisk said:
So was Lady Dianna. Until she was killed off, 20 years ago, today.
Click to expand...
So you like the conspiracy theory, Chris? Sounds a bit too Mission Impossible for me ... but then they said Lance Armstrong couldn't possibly be a drug cheat too!
 
Piranha Brother 2 said:
So you like the conspiracy theory, Chris? Sounds a bit too Mission Impossible for me ... but then they said Lance Armstrong couldn't possibly be a drug cheat too!
Click to expand...

And Dean Mercer was too fit to have a heart attack and die .....  I've said it for the last 20 years Quentin.
How else could big ears marry horse-head and still be in line for the throne?
 
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