[QUOTE=97 SL320;380406
Lastly, the biggest killer of keys is a weak car battery that disrupts the read / write cycle when system voltage drops too low during cranking. These keys send a code to the DAS box, if the DAS box expects this specific code, the car is released to run. The DAS box then sends a new code to the key and updates it's internal table. Interrupt this cycle and you are out of sync with the code table.[/QUOTE]


I had this mismatch happen on our 99 BMW Z3.
One day the car just cranked, no start, had to tow home.


I found a place online that would disable the key to computer handshake. Had to send in a component or two, as I recall..... Bottom line is that the "fix" has worked for the last 4 years......


I had the no start problem on our W140 as well (99 S500), ended up swapping out the components from a parts W140 to get it going. One of the things I remember is that we took a key and the sensor ring that circumnavigates the ignition key and taped them together under the dash. That way the ring senses the right key, and the lock is now purely a mechanical lock. Never did see a similar service offered for MB that I used for the BMW.


Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles