LM2100 Mower Not Starting

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I've got a 21" LM2100 mower that was manufactured in December 2015. With a fully-charged 5Ah battery it will not start.

I have checked all three safety interlock switches in the handle, side rail, and the base of the lower handles. All three safety interlock switches appear to work, and the battery light turns green when I attempt to start the mower - but there is no action. The blade spins freely if I turn it by hand.   I do not get a battery warning light, and I can get the 'headlights' to turn on with no problem. Just no response from the motor.

My mower is not warrantable, so I took the liberty of disabling the side rail safety interlock switch with a zip tie. Makes troubleshooting the system a bit easier I think.

All wiring harnesses appear to be compete, and uncut and fully connected.

I did a quick check of the thermal fuse in the battery compartment, and it has continuity and appears good.  I then checked the 60W 5K ohm wire-wound ceramic resistor, and in-circuit, it measures about 0.55 ohms. I kinda think this might be my problem, but was curious if that is a correct in-circuit resistance value before I start cutting and desoldering the resistor.

I'm not opposed to subbing in a different (and generic) 60W motor controller board if anyone has a known good sub, and/or a suitable schematic for this beast.

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Posted 2 years ago

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Official Response
What is the background on this mower?  Did it run before, and now doesn't run?  Or did you buy it on craiglists "as-is" (e.g. not running)?  If it was running, what were the failure symptoms?

Without a good schematic (which to date no one has been able to find), I would not conclude that the in-circuit 0.55 ohms is a problem.

If you have the mower apart, the next thing I would recommend is to start measuring voltages.  Start at the battery box, and go toward the handle.  You might also want to look at the safety interlock switch you disabled, to make sure by-passing it as you did had the correct effect (e.g. if you're measuring voltages, the by-pass way lets voltage go past).