Hey guys, new to the forum here. Please forgive me for starting a thread right off the bat but after extensive searching I couldn't find an answer.

Rebuilding myself a 2003 CBR600rr...everything is working great except my fan will not turn on and I have no temperature indication on my gauge. The local Honda "expert" tells me that the ECT only controls the fan and not the temp readout. Is this true?

I traced the issue back to the ECT, I know it must be the ECT sensor because when you unplug the ECT (just a thermistor), the circuits resistance drops below the specified limit (730Ohm or something) and the fan kicks on. I ran a crude test on the ECT with it out using the hot coolant method with an ohmmeter as described on 20-16 or so of the Service manual. EVENTUALLY it drops to the low resistance but I feel it takes WAYY too long, plus I don't have an accurate thermometer..

Anyway, main questions are:

Is it possible I have an air bubble in the thermostat and the ECT isn't getting hot? Or is the ECT probably just shot..?

Could a bad ECT be why I don't have a temp reading on my display, or is there really a separate sensor?


Thanks guys! Any help is greatly appreciated!

 

Hey guys, just wanted to say that I solved this mystery. Turns out I had a faulty wire in the sub harness. :-P

 

I suspect the ECT isn't working. My Haynes manual shows 3 wires off the ECT. A pink/white wire goes to No 18 of the Engine Control Module. A green/pink wire goes to No 1 of the module and a green/black wire goes to the temperature gauge on the instrument panel. Both of the Engine Control Module connections are on the right hand side of the Engine Control Module. There are 22 connections on each side of the module numbered 1-22 left to right, according to my Haynes manual wiring diagram. I'd replace the ECT and hope that cures your problem. Other than that you could use a manual off/on switch direct to the fan. Bypass the sensor by joining the feed wires together that supply it and you can switch the fan on or off as you deem necessary until you get your new ECT.