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Massimo T-Boss 410 has lost all electrical power


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Hopefully someone out there is a T-Boss 410 electrics expert or a Massimo mechanic is viewing this. I parked my 410 and it was working great. I came back a week later and attempted to crank it and nothing. Turned the key and no power. Figured it was a bad/low battery so I charged it. Still nothing. Attempted to jump start it and still nothing. Usually when I put the key in and turn it to the first position, the display comes on and I hear the ECU and other items boot. Now it is doing nothing. 

I slowly went through the electrical system and found the main fuse attached to the starter relay, part 71602 (pic 1) blown. I figured replacing this fuse would fix my problem. It didn't. I then ordered a new starter relay thinking maybe that part had gone bad and caused the fuse to blow, but a new relay did not fix the problem. 

I have found a work around for starting the machine. If I take one of the purple/black leads (pic 2) and insert one of them in the bottom right of the starter relay (pic 1 and 3) then the machine will get power even with the key in the off position.  I'm bypassing something but don't know what. I can use my right hand to hold the wire against the lower right of the starter relay, reach over and hold the brake with my foot, then take my left hand and turn the key and it will crank. As soon as I remove the wire from the relay the machine shuts down. I have even removed the power distributor box and it will still get power when I touch the wire to the relay. Of course this is not the way it should work but if I can't solve this problem somehow I may just have to rig a connector to the relay and bypass whatever is causing the electrical issue. Massimo has told me the purple/black wires on my model are not used.

Any help in figuring what my problem may be or other items I can try?





Pic 2.jpg

Pic 3.jpg

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Found this service manual.



on page 8-14 has this diagram of starting circuit.



From the diagram. The key switch gets power from the fuse in the starter solenoid. Then key switch sends power thru a fuse to a brake switch. Thru a safety switch back to the starter solenoid. To engage the starter.


So the key switch gets power thru the solenoid fuse. Main 12V+  goes to stud on relay. Then thru fuse. Then to wire going to keyswitch. When you replaced the solenoid. Make sure the main battery cable connected to the stud that provides power to the fuse.


Hope this helps.

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  • 2 months later...

No. I ordered an extra light switch from Massimo, took the small black wire (second pic from top) and connected it directly to this switch and then back to the starter relay creating a master cutoff, bypassing whatever issue I have. Now I just push the cutoff switch on and it powers everything up, then crank as normal. The ignition switch only cranks, it doesn’t turn it off, so to power down I turn the ignition off then push off my “master cutoff”. It’s working but not like it’s supposed to. 

First chance I get I’ll probably trade for something newer or see if my local Massimo dealer can figure it out. 


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