Hi does anybody know where to measure the resistance on the Ignition Coil?
I got a new coil, but I could not get any resistance reading no matter where I stuck the multimeter.
Background, my "cylinder #5 misfire" problem returned, and now it seems to happen almost every day!. So I got a new coil, and would like to measure the resistance difference between the old vs new to determine if its the coil could be the cause. I've already changed the plugs and the wires.
There should be no electrical connection between ground (the body or frame of the coil) and any other terminal. If there is the coil has an internal short to the frame and is bad. There should be a low resistance connection between two of the low voltage connection points in the cable harness connection point and a much higher (Kohms) reading between either of these two points and the high voltage towers. I have not had the need to probe the coil on my 500 SEL but this is a general guide to ignition coils as on my older 560 SELs. The low voltage windings which are connected to the ignition system are connected internally in the coil to the high voltage windings which have a much higher resistance due to the greater number of turns and finer diameter wires.
Just to followup, I put in the new coil, and the Cylinder 5 doesn't misfire anymore! Its been good for 2 weeks so far, and I floor the gas whenever I have a chance, and the engine never misfires anymore.
Now, does anyone know if coils "age" or have performace degrade over time? I am considering replacing the 2 other coils, since they are as old as the one that failed. These 2 original coils work fine right now, but I am not sure if they will fail soon, and also don't know if aging coils might cause performance loss?
Linear Mode
