Corroded ground strap? Have you done an amperage draw test on the 2nd battery? Maybe it too is discharged. I have seen it before.

__________________
Doug

1987 300TD x 3
2005 E320CDI

Installed new battery and tested, it is fine. All in grounded properly as well.

I also checked the overload protection relay fuse and that is not blown. Any other suggestions ?

Tempting the obvious : Have you tested the starter? Do you have power otherwise (ie windows, radio and stuff works?)?

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1989 300E 144K

I have not tested the starter no, but i cannot see this being the problem as it was perfectly fine prior.

I have all other functions that the battery should produce yes ( lights, horn, etc. )

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Either or both ?????


Try "N" position on shifter...............

No cranking at all and no sign of it even trying to fire. I tried starting it in N and still nothing.

maybe the ignition switch ?

>

Well , if it does not crank, then it certainly can't attemp to fire ...that is what was confusing about your complaint.
Your complaint is the car does not crank, meaning the starter circuit does not engage.
Do the dash lights indicator lights come on when you turn the key to RUN position?

On the W123 diesels there are easily accessable terminal block that can be jumped across so the motor can be turned over from the engine compartment while adjusting the valves. Maybe the W107 has the same feature? This would allow you to bypass the ignition switch.

__________________
Doug

1987 300TD x 3
2005 E320CDI