71 250c not sparking (114.023)

[snake109]

i bought a 71 250c with an I6, i think its a euro version, the number is 114.023, anyways the previous owner put the battery leads on backwards and messed something up because the ignition isnt sparking now. its getting plenty of fuel though. i started testing voltage in the system but without a wiring diagram im running blind. does anyone have a diagram or sugestions on what to check specifically, all the fuses are good and i allready replaced the coil. thanks

Originally Posted by snake109

i bought a 71 250c with an I6, i think its a euro version, the number is 114.023, anyways the previous owner put the battery leads on backwards and messed something up because the ignition isnt sparking now. its getting plenty of fuel though. i started testing voltage in the system but without a wiring diagram im running blind. does anyone have a diagram or sugestions on what to check specifically, all the fuses are good and i allready replaced the coil. thanks

are you getting power to the coil? there is a controller box(mercedes calls it transitorized ignition) that usually fails on these models, if you have no power to the coil, that is likely your issue, try putting 12 volts to one of the ballast resistors near the coil, also don't neglect the obious, did you check the ignition points?

[snake109]

thanks. yes i checked the points. i tested the coil and it gets .14 volts i think when i crank it, not sure what the spec is. where is the controler box located?

[smithrjd]

I belive that it is under the battery box. A sealed unit, at least on my 71. Not much one could do with it if it is not working. Check the technical links, there is a site with the correct wiring diagrams.

Ron

[MunichTaxi]

from memory, I believe the coil should be getttting 2.8 to 3.2 volts (blue coil)