Ok, so this morning I was riding my 630 and all of a sudden the fuel light came on (just filled it up last night), got a loud backfire, and it sputtered and died. Now I can't get it to turn on. At first, if I turned the key on it would flash a jumbled mess on the screen, show the usual screen for a second, and then turn off. Now it doesn't come on at all. I've checked all of the fuses and electrical connectors except the ones between the tank and the frame (if there are any under there). The battery is good, hasn't seen rain in weeks. I'm thinking (and hoping it isn't) a dead ECU. I don't have any dealers around me to bring it to either
Pull the gas tank and inspect the wiring under the tank. Look for frayed wires or insulation worn through.
Do a load test on the battery. It can be fine with no load, but then short out when under load. Also check battery ground. Paw Paw
I can't recall a documented case of dead ECU on our bikes. Most likely a connection or battery issue. The first thing I do is 100% eliminate the simple stuff. How do you know the battery is good? Connections are clean - frame grounds are clean - plug and inspect terminals on every plug you can see. It sounds like the bike has possibly lost power going or coming from the key switch so track down ignition switch harness plug and check it. Looking at the wiring schematic, red should be 12v and black is ground at the ECU. .
If you go through the harness and check the battery and still think it might be the ECU, I've got a spare SMS ECU you can try out.
I went through a very similar experience. On mine I had a bad fray/rub through in the wiring leading into the plastic connector that connects to the voltage regulator (and I mean close to the VR.) It's tight under there- was rubbing the subframe/edge of battery tray. Best to unplug or dismount the VR to get a good look- not readily visible at a glance.
