My Makita DCS520i chainsaw will not shut off. I replaced the kill switch and that did not work. The wire and connections look fine. I assume the ignition coil is ok since it starts fine. Anyone know what it could be?

Not done anything with Makita, but i would assume this is a class 11 double insulated product if there is not a third earth wire, the US normally have black as the live and white the neutral, these wires would normally go to one side of the switch, or if there is a micro switch on the hand guard one of the wires will go to it and a wire from the other side of the micro switch to the trigger switch,

check the seat switch and the blade engagement lever switch

There should be only 1 screw and one wire connecting the kill switch. The kill switch simply grounds out the ignition. So it is difficult to install improperly. The wire coming from the switch goes directly to the ignition module.

The on/off switch must be connected and switched to ON to run. The kill switch if it is the type of switch that you must press and hold then not it only grounds the coil to stop the spark plug from getting power.

So my answer is no.

Never use stater fluid on small motors it will blow the ring out of them. Use carb cleaner, it works the best. I've worked on these things for most of my life.

The switch grounds the coil and kills the spark. Make sure you dont have a rub through on the wire coming from the coil. Better yet disconnect the coil wire. If this works you will have spark but wont be able to shut it down. Verify good spark, then repair the wire.

Hope this helps, Matt

If you need further help, I’m available over the phone at https://www.6ya.com/expert/matt_8dbc24bf722649ac

a single wire from the coils connects to the on-off switch and when you switch it of just earths that wire trace the wire and check the connection

The replacement switch, is it Makita and was it a direct replacement for the original part? That could make a difference. I looked at the schematics for this tool and they do not furnish the wiring codes but I think you are on the right track. To make sure though I would call Makitas tech support people at 1-800-4625482 and have a wiring explosion sent to you. Let me know if you still need more help and I will contact them or call a local dealer that I know.

While attending college, I worked at a tool rental center and learned many tips and tricks from the mechanics. The problem that we heard the most from customers was that the machine would not start. Your your machine at least starts and runs fine, however will not shut down with the factory kill switch. Many times when replacing the mag. (spark coil) the kill wire would rub against the flywheel and break or over time the conductor wire will break inside the insulation. If you kill switch only has one wire, then all the kill switch does is short the mag to ground. Simple test is to remove spark plug, re-connect wire to plug, touch plug to engine and pull rope to observe spark, then short the tab on the magnito to ground, should be no spark. If you still have spark, coil is defective however good enough to run engine. Kill with choke or pull wire. If no spark with test, make new wire from tab of coil to kill switch or any switch that will short tab to ground. Good Luck

Hi

The off switch of the chainsaw has to establish the continuity to kill the running engine.First check the switch with a measure apparat.Then check the continuity of the two wiring harness,sepparately.One wire is atached to the ignition module with a screw and goes to the off position of the switch.The other one towards the on position of the switch.Check the spring!

regards savumihai71