Dillinger1977
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| posted on 17/6/07 at 03:44 PM |
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water temperature sensor
My racetech water temp guage doesnt register anything (its stuck at 40, the lowest reading) and cant remember if it ever did work when it came back
from MNR to get the electrics done.
im pretty sure the guage is wired correctly, looking at the colour of the wires to the icons on the back of it, and its got a single blue wire that
runs to the temp sensor thats inbetween the r1 thermo and the radiator
the sensor is installed in a welded in screw fitting onto the coolant pipe and looks a bit like this (but with a bullet connector on the top not a
screw fitting)
as a completely random test, i unplugged the wire from the bullet connector at the top and touched it against the brass body of the sensor, this made
the needle move up to about 60.. the first time its ever moved.
i'd just had the car idling for a bit playing with the carbs so could be an accurate reading?
if it is, why would it work by touching it against the outside and not the actual connector?
anyone got any idea what might be wrong with it, given my useless description? 
-Rog
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andyharding
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| posted on 17/6/07 at 03:53 PM |
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Sounds like the gauge is shagged or your engine doesn't have a good earth.
Earthing the wire to the gauge (by touching the body of sender) should make the gauge read off the scale!
Are you a Mac user or a retard?
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chockymonster
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| posted on 18/6/07 at 12:27 AM |
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if the boss is in a rubber pipe then it won't have an earth, wrap a wire around the temp sender and touch it to the engine block and see if that
gives a reading.
I've had the same problem with my oil temp sender.
PLEASE NOTE - Responses on Forum Threads may contain Sarcasm and may not be suitable for the hard of Thinking.
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02GF74
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| posted on 18/6/07 at 11:30 AM |
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bascially the way thesething work is the temp sensor is a a negative coeeficient of resistance.
in simple terms, as it heats up, its resistance decreases.
The guage is nothing more that an ammeater - the more current flowing trhough it, the bigger the deflectiopn of the needle. Now if guage has power
supply, 12 V from battery connbected to it and other ends goes to the sender and then earthed to complete the circuit, as the resistenace of the
sneder changes, so moves the needle.
2 test to try.
1. unplugg wire from sender - guage should register 0.
2. earth wire from sender tor known good earth - guave should read max - more than you saw.
The sender's body must be earthed- as someone said, if it is in between 2 rubber hoses, that ain't good enough as you are relying on the
water/coolant mix to complete the circuit - whcih is not good enough.
if you have DVM, measre resistence of sender cold, plunk into boiling water and measrue again - it should change. Cannot rememebr what typica lvalues
are. that would tell if the sneder is knackere but without the actual values, we cannot know for sure.
Also check if you guage needs a voltage regulator or is connected to battery - that may account for your low reading.
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