Troubleshooting MS261CM with ohm meter

[Robnjay]

I’m trying to verify that I actually have a bad coil on this saw before I spring for the new part, here’s what I have done so far:
Replaced the solenoid with a new repair kit (white solenoid + orange filter)
Disconnected the 2 wire harness from the coil and measured both wires to ground - black is open until the lever is moved to the off (up) position, then shorted - red measures 36 ohms to ground. This is probably the resistance of the solenoid coil.
Measured the coil:
Primary is 1.87k ohms
Secondary is 2.4M ohms
Primary to secondary is 24.7k ohms
Zat 4 no spark…
Buy the part???

 

[stihl #1]

This is an early CDI:

This is a M-Tronic:

You can't ohm out between the primary and secondary because the circuit board is in between them. I have never tried to compare readings from one known good module to another, so maybe there is something there but to my knowledge STIHL never documented it.
The only thing I have run across is a break in the wiring harness that would give an intermittent open, so test the wires from end to end for continuity while flexing and stretching them and if they are good, and you have a new solenoid, then it probably is the module, and the only way to verify would be with the MDG1. I think if the wiring harness is open you get one spark on the tester and then no more, but that was a long time ago when I saw that.

 

[Robnjay]

I managed to get ahold of a service manual and Stihl shows the primary reading to be 1.5 - 12k. No spec on the secondary (red terminal to black terminal). I’m not sure that my primary reading ensures a good part…

 

[Robnjay]

I managed to get ahold of a service manual and Stihl shows the primary reading to be 1.5 - 12k. No spec on the secondary (red terminal to black terminal). I’m not sure that my primary reading ensures a good part