no spark from ignition coil
 

patient is 1987 420sel....

the other day i tried to start the car which is my daily driver....no start and no history of hard starting.

mechanic looked at ignition coil and saw 12vdc but nothing coming out. therefore we thought coil bad.

we replaced the coil and got 12v on both sides of the coil. still no start. cranks / turn over....no spark

got the cps cable and am looking for an EZL ignition module...will replace the module first and then the cable.

will update once engine starts.

Check the Crankshaft Position Sensor.

http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1987@@1987&makeid=63@@MERCEDES+BENZ&modelid=6263%3AED|10000055%3AMBC|153 3@@420SEL&keyword=sensor@@sensor&catid=All@@All&subcatid=P%3A242838@@Crank+Position+Sensor&applicati onid=W0133-1600116@@Crank%20Position%20Sensor&mode=PA

slk230red, how does one determine the crank position sensor is bad?

If you stick a multimeter on the EZL plug end of the lead, red on the inner and black on the outer, and get nada the CPS is cactus. A reading of around 450 upwards it should be okay or at least start.

benzme, I take it you're checking resistance of the crank position sensor cable? What unit is the 450?

Correct, resistance. Range should be 680 to 1200 ohms.
The CPS on my 190E 2.3 measures 851 ohms when cold and 924 ohms when hot.

I also measured the AC output of the CPS while the engine is being cranked.
Cold measures .842V ac and Hot measures .986V ac.