Out of the blue two days ago I cranked on my ever dependable 420 SEL and the idle immediately raced and wouldn't stop racing. The yellow ABS warning light also came on and stayed on. If you wait long enough (two minutes or so) it will finally slow down to normal---or put it in gear and it wll return to normal idle, but only after burning rubber and jerking the trans big time when it engages at that high speed. It does it every time, whether warmed up or cold. Sounds like computer stuff or electronics at the least which leaves me out in the home repair department. Any suggestions would be much appreciated. Bear in mind that I live far from a MB dealer. Thanks in advance,
Rob Hudson

Change your overvoltage protection relay. That's the cause.

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Regards,
Aaron

Thanks very much Aaron---I made an appointment with an independent MB mechanic to do what you suggested. He said he agreed with your diagnosis completely. We'll find out Wednesday. This forum is truly a great thing. I wonder how MB owners managed without this and the net in the stone age.