My 99 E320 ck engine light is on, went to car quest , then auto zone for free scan, both were unable to get power when connecting to OBD port under dash. I can't find an itemization in either fuse panel for OBD, but i checked most fuses i thought would correspond and didn't find any fried.....something tells me its not as simple as a fuse. Any ideas most appreciated. Thx Hunter