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Old 02-17-2018, 08:05 PM
97 SL320 97 SL320 is offline
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Join Date: Jan 2012
Posts: 7,534
Yep, 97 was the first year for the RFID chip key for the W202 , W210 and R129. What is your build date?

You should have a black / chrome antenna ring around the ignition lock, the has a small black wire that leads to a 3 x 4" black box behind the instrument cluster. This box reads the key then sends a message to the engine computer to let the car run. The chip key / black box and engine computer are all programmed together, swap one and the car won't continue to run.

Also know, a new code gets written into the key after each start attempt. A weak cranking battery can disrupt the write sequence and that key will no longer work.

The black box looks like this, the chip in the remote fob is a PCF7935. If you have a non remote valet or clipped head pocket key, they also have a chip.
Attached Thumbnails
W202 stuck ignition EZ Solution-04.jpg  
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