I have a 1992 300e 2.6, all original, and, among some small issues, the stereo (am/fm and cassette) will work perfectly if the exterior temperature is over 72F. If it's below 72, it gives me an E 2 error. I assume there is a loose connection or a barely separated break in a wire between the trunk amplifier and the unit in the dashboard. Rather than try to test all of the wiring, is there any particular wire that might be most likely the culprit?
Thanks in advance!

Common problem with that model of stereo. Pretty sure that the only solution is to have the head unit rebuilt or to install a refurbished replacement or Freire the system for an aftermarket unit.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Thanks for the information! I never would have guessed.