Temperature gauge

WillM · Jul 16, 2022

My temperature needle springs right to the top. Bike is definitely not overheating.
It must be something to do with the connections / wiring in the back of the clocks as it will momentarily fall back when moving the cluster and loom. Cant pin point it. I loosened and tightened all connections.
Could there be a break in the loom?
Does it indicate a bad earth?
Which wire is the earth, so I can try to bypass a possible broken earthwire, as a test.
Thanks.

Corrugated · Jul 17, 2022

See lots of dirty connections at the terminals, try cleaning the contact points and terminals thoroughly to begin with..

maleko89 · Jul 17, 2022

Check the small black wire/ground that connects to the top of your coolant manifold just rearward of the radiator cap. If that's loose/dirty, needle will go crazy.

MaxMidnight · Jul 18, 2022

My best guess is that the green/ red wire is going to earth which is why you are getting the full scale defection.
Check for chafing.

Aquamax · Aug 1, 2022

I would also look at a bad sending unit. Or the plug connection at the sending unit.

Fire-medic · Aug 1, 2022

This seems to be getting some use these days and well it should for electrical issues. If you told us the year of the bike, that helps. Also where you are, two things to put under your screen name to help you get assistance.

NOTE: overlap is evident on these diagrams. Also please pay attention to the model years represented.

NOTE: overlap is evident on these diagrams. Also please pay attention to the model years represented.

Comments on checking ground connection, and the landing of the wire at the thermocouple by the thermostat are how to proceed. Wire ends should be shiny-bright, and free of corrosion. Also, checking the wire for continuity while flexing the wire, along its path, and any wear spots where the wire could be grounding out. I can't recall ever having a sensor go bad, but it could happen. On other vehicles, I've had the point where a wire being crimped to the brass fitting spade terminal, round brass through-bolt fitting, or whatever, has failed completely, or has severed nearly-all the wires, leaving only a marginal number of strands providing continuity. Sometimes it's been in that first inch of wire from the terminal, and under the wire insulation. If you have a thought that the wire has failed somewhere and you haven't found the break, give the circuit the AIP-treatment (abandoned in-place) and run a new wire from the thermostat thermocouple to the back of the gauge. Label it so you can easily identify it, and use some of those teeny nylon wire ties to bundle the OEM wire and your replacement together to help you recognize what's been done. A bit of dielectric grease on electrical connections helps to keep them free of corrosion.