1992 300E/E320

just did modification to increase my idle since i have been experiencing low voltage at idle (inspite of new alternator).

also had a voltage meter installed to warn me to reduce load in case of low voltage.

browsing the previous topics on this modification is difficult to understand and a mistake may pry the wiring harness.


For DIY, to illustrate how it is done:

1. look for X26 connector (rectangular box with 12 pole connections) under the lower fuse box on the engine compartment on the drivers side

2. identify the pure violet (or purple) wire, unplugged the connector box, open the male connector side and remove the
violet wire-male connector from the connector box.

3. Plug back the connector box and ground the male connector violet wire to the ground.

the female connector is the hot wire from the ignition switch.

the male connector is line to the ECU and this wire is to be grounded to increase the idle by 50 to 100 rpm. if this wire is
unplugged and not grounded, you will note a high and fluctuating idle.

if you want to be sure if you got the correct wire, test for voltage and should have no voltage with ignition on.