Does reversing the battery polarity blow the ECM

Geoff Smale

.020 Over
Joined
Apr 13, 2017
Messages
17
Location
Whakatane New Zealand
Ride
2005 Rocket 3 ,1971 Kawasaki Mach3
I have been working on bikes for 40yrs. Yesterday i refitted the battery in my R3 that i am rebuilding and reversed the polarity! yes I know Dumb amateur mistake ( I have beaten myself up enough about it already) . What i am asking is does this blow the ECM or anything else. I have no spark but this is a total put back together including a new second and hand wiring loom so i cant say it had a spark before and now its not. The Fuel pump runs when the key is turned on the speedometer needle does it sweep ( the rev counter does not sweep).
any thoughts?
 
I would say probably no permanent damage - these things are designed with expectation that sooner or later someone will do just that.
If pump is priming you know that the ECU is at least powered and giving the appropriate times output to the pump. And if it cranks then ECU also enabling starter relay too
If no spark, then check for sidestand/neutral interlock (is neutral light on?) & the CPS is connected/working
 
 
I think you will be ok, the early bikes are pretty good that way. That is the ECU with the square plugs, right? Are you cranking it with the plugs out?
 
Neville Lush said:
Did you try and start it?
Click to expand...
I purchased this bike as an insurance write off. It had cosmetic damage but the owner had decided to remove a few things before the insurance company picked it up. one of those things was removing a power comander by cutting the main loom rather than unplugging it. So i have replaced the loom and i have reassembled the bike. Filled it with fuel and attempted to start it. It cranked but didnt start. but the battery was a little low so i removed it and recharged it. Then i installed it reversed. turned the key on nothing lit up. so i checked the battery. Refitted it turned on and the speedo needle swung around lights came on( the rev counter needle did not swing), fuel pump started engine cranked but didnt start so i removed a plug earthed it and cranked the motor and found no spark. The neutral light did not come on before or after the reverse polarity. i pulled the clutch ficked up the side stand cranked it no spark. It could be something else not conected but before i pull things apart to check i thought i would ask about the ecu
 
Double check all the plug in connectors, especially since you replaced the wiring loom.
 
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