1994 Mercedes C280, Cylinder 1 & 6 no spark.Changed 3 coil packs, changed wires and spark plugs.Engine wire harness look fine.Cylinders 2,3,4,5 have spark.Coil number 3 Controls Cylinder 1& 6; and i use multi-meter to check for voltage. 11.70 volts with key on position, 13.80 volts with ignition on. I need to figure out could it be a sensor or the ECU( Computer) or Engine? Any advice would help thank you.
This looks like either a broken wire between the coil and the computer or a defective circuit in the computer. Apparently the wires are not rodent proof on this vehicle.
The circuit has the coils always receiving voltage. When the computer decides to fire a plug, it opens the ground side via a power transistor inside the computer.
You should have two or three wires to each coil. If the voltage is the same on all the wires, then you will have to find out which of the wires goes to the computer and check that wire for continuity. If it has good continuity, then you have a computer problem.