Coolant Temp. Indicator - Honda TRX Forums: Honda TRX 450R Forum
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post #1 of 3 (permalink) Old 05-18-2017, 06:40 PM Thread Starter
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Coolant Temp. Indicator

Purchased an 07 450er last week. The previous owner had a toggle switch hooked up to the electric fan. I was hoping to reverse this and put it back the way it was but there was a wire cut preventing me from doing so. The red temp. indicator light on the dash isn't working at all. The wiring coming off the indicator light and the wire coming from the temperature sensor on the motor are both intact and connected to the ICM. There is a black wire coming out of the wiring harness that use to go to the blue plug that the fan motor plug goes into. That black wire was cut off flush on the female side of that blue plastic plug and the other end cut off at the wiring harness.

That blue plastic plug where the fan plugs into, is some kind of voltage reducing plug (not sure what the technical name is) the wires going into the bottom off the fan motor are larger gauge than the wires coming out the top so I cant directly splice them together.

If the temperature sensor is bad, will the red indicator light work at all? It supposed to come on for a few seconds when turning the key on, correct? I would still like to have the red light working even if the fan is wired to a switch.

Last edited by Equalizer; 05-18-2017 at 06:42 PM.
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post #2 of 3 (permalink) Old 05-18-2017, 07:21 PM
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You need to hook up the yellow/blue wire from the 8 pin connector to the thermistor of the engine, at room temp you should read about 500 ish ohms at 24 Celcius from the pin to the block, the fan is driven by the CDI unit

2008 TRX 450ER XC racing
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post #3 of 3 (permalink) Old 05-19-2017, 05:39 AM Thread Starter
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Thermistor? Are you referring to the Engine Coolant Temperature Sensor (ECT)? The blue/yellow wire from that is currently still connected to the ICM (Ignition Control Module). The names I'm using is what there called on the wiring diagram in the service manual.

The fan motor is currently disconnected because the plug has been cut off.

It looks like I'm gonna have to stick with having the fan connected to a toggle switch. I just want the red temperature light to work like its suppose to.
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