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Hi Guys,

This thread is for electric gurus! I've replaced the ECM of my 2004 CBR600RR twice now, something is surging and keeps frying them.

It all started with very poor idle, very rich conditions and 4 errors on the MIL System:

1 Blink: MAP Sensor Malfunction
7 Blinks: ECT Sensor Malfunction
8 Blinks: TPS Sensor Malfunction
9 Blinks: IAT Sensor Malfunction

I went through all steps to troubleshoot these errors in the service manual: continuity, voltage measures, resistances etc. Most results end with "Replace the ECM".
When I should read about 5V coming out of the ECM, I read 0V.

So, I replaced the ECM. The bike started right up and run great for a few miles with no more error codes...until it died. Again.

FI MIL Light blinking like before. Back to square 1.

I'm guessing that something is surging the ECM, like a ground or a solenoid shorting. Bypassing any fuse. The rectifier is under specs and the stator sends 13.9V at 5,000rpm. All good there.

I'm quite mechanically inclined but this time, I'm baffled...

Any help is greatly appreciated!

Thanks guys.
 

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says here the stator should put out 60+ volts at 5000 rpms. i'm not saying thats the problem.low voltage output could cause a poor idle.a bad rectifier can fry electrics
 

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says here the stator should put out 60+ volts at 5000 rpms. i'm not saying thats the problem.low voltage output could cause a poor idle.a bad rectifier can fry electrics
That is testing the raw AC voltage coming from the stator windings.
Pretty much irrelevant because his DC output voltage is right where it should be.

Low voltage usually doesn't fry things.....except maybe motors......and high voltage is a more likely culprit.
Might be good to test the stator windings just to be sure though.
A shorted rectifier can sometimes put out a big AC component over the 13 V DC and cause problems too.

And finally, probably a good idea to inspect as much of the wiring harness as possible looking for insulation rubbed off against the frame or wires chewed by varmints.
 

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Did you test DC output on a cold reg/rec or hot after running for 14 to 20 minutes? I never check charging unless the system has reached and been at operating temp for at least 15 minutes. Ive seen plenty of Hondas charge correctly cold, but hot the voltage spikes upwards of 16 to 17 volts. Go through all your system grounds also. Check your fuel pressure regulator on a side note as the diaphragm cam go bad and feed raw gas to the cylinder the vacuum is connected to.
 
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