I just tested the coil on my 90 300SEL as I am having hard start when warm problems, I think it is fuel related but thought I would test the coil anyway. (see other post ) Between the two terminals it is 2.5 ohms, I thought 3-5 was normal. Also between the terminal and the high tension lead it is 9.5 K ohm or 9500 ohms. Is this within spec? battery is at 12.5V not sure if that makes a difference.

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1987 300 TDT
1990 300 SEL

i've gotten good results testing coils with ohm meters only to have them fail under load. they rarely quit, but they do get weak and still throw spark. that's why an ignition scope is needed to check the coil while running. failed alot of coils of that particular design that way. another sign of old age is the white or gray area that develops around the bracket. that's a sign that the coil is arcing to the outside-least path of resistance. good luck, chuck.

ya but is that within specs? I have to start somewhere.

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1987 300 TDT
1990 300 SEL

One more question, there is a brown wire that is by the coil, I didnt notice it when I removed the coil for some reason. I assume it goes to ground? There are two wires each side of the coil and one large black that was grounded with case and this small brown wire. Anyone confirm for me?

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1987 300 TDT
1990 300 SEL