[Theslowrider]

A little background, I purchased a track converted 07 gsxr600 and it had the typical light deletes, keyswitch deleted etc. There's been one electrical issue I can't figure out for the life of me. The radiator fan won't come on, even above 221 degrees. Started by checking for voltage at the fan, none, ground side wire was good and had 0ohms of resistance. Put 12v to the fan and it spun as intended. Checked the fuse for the fan and it was good. Swapped relays with the fuel pump and there was no change, fan didn't engage. No warning lights or indicators for this either. Tested the wire from fan to solenoid connector it was 0ohms, checked from ecu to solinoid connector l, 0ohms. Checked kill switch to solinoid connector, 0 ohms. Can't remember the last wire but it was good as well. Any ideas on anything else before I chalk up a ecm??? Thanks!

 

[BillV]

Test the temperature sensor as described in the service manual. The resistance should be about 180 ohms at the boiling point of water. If it's OK, plug a 150 ohm resistor into the connector for the sensor. The readout on the cluster should then be about 108 °C / 226 °F and that should be enough to turn the fan on (140 ohms should be about 230 °F). Next check the colors of the leads to the fan relay. I think they should be O/W, G/R, O/R, and B. The K6 750 manual shows O/W, O/R, O/R, and B but I think that's a typo. Assuming it's G/R, measure the voltages at the leads with the temperature sensor and fan relay plugged in, the ignition and kill switches on, but the engine not running. The O/W, O/R, and G/R should be 12 V and the B should be 0 V. Then replace the temperature sensor with the 150 ohm resistor. The O/W and O/R should remain at 12 V while the G/R should drop to near 0 V and the B should jump to 12 V. The key issue is what happens to the G/R. If it doesn't go low, start the engine and check again. If it still doesn't go low, the ECM isn't doing it's thing. It's possible that the racer flashed it to disable the fan. It sounds like you've already ruled out a damaged B lead from the relay to the fan.

 

[Theslowrider]

Test the temperature sensor as described in the service manual. The resistance should be about 180 ohms at the boiling point of water. If it's OK, plug a 150 ohm resistor into the connector for the sensor. The readout on the cluster should then be about 108 °C / 226 °F and that should be enough to turn the fan on. Next check the colors of the leads to the fan relay. I think they should be O/W, G/R, O/R, and B. The K6 750 manual shows O/W, O/R, O/R, and B but I think that's a typo. Assuming it's G/R, measure the voltages at the leads with the temperature sensor plugged in, the ignition and kill switches on, but the engine not running. The O/W, O/R, and G/R should be 12 V and the B should be 0 V. Then replace the temperature sensor with the 150 ohm resistor. The O/W and O/R should remain at 12 V while the G/R should drop to near 0 V and the B should jump to 12 V. The key issue is what happens to the G/R. If it doesn't go low, start the engine and check again. If it still doesn't go low, the ECM isn't doing it's thing. It's possible that the racer flashed it to disable the fan.

Thanks Bill! I'm going to have to check that out this weekend. Will certainly update you with any findings.