W201/124 Mirror Heater Relay...
 

Anyone know where the relay is for the Heated Mirrors on the 1986 300E is located? Same for 1987 190D 2.5 NA? Where does it get its Power from? Just trying to rule it put as a source of BATTERY Discharge in Cold Weather! :confused:Thanks!

The 1986 W124 cars do not use a relay for the heated mirrors, power is drawn through fuse 8 whenever the key is in "run or start," as the Germans say. This is the same power connection that the outside (right side) mirror control switch in the console uses. Not sure of the W201 but probably the same, no relay.

The connection uses black/red wires and goes through X30, a multi-pin connection terminal (part of the power distribution network) located under the driver's carpet, forward of the left kick panel. It will have +12 Volts on it anytime the ignition is in start or run.

Jeremy

Put your DMM inline with the battery and measure amp draw. Do not attempt to start the car in this configuration of course. That reading will indicate if the battery is draining via the car.
Alternatively....You can remove the battery from the car, charge it up to 12.68v then let it sit overnight disconnected. In the AM check and ensure it still is above 12.6v at the very least.