Couple of Wiring Tips - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 07-12-2015, 06:59 PM

Here are a couple of wiring tips for testing and other temporary purposes. This should work for any car that uses plug/socket connections like our 123, 124, 126, 201 and similar Benzes. As always, YMMV and be careful not to let the smoke out of any electronic devices!

1. If you need to make a connection to a relay or other device, the proper method is to open up the socket into which the device plugs and carefully solder on an additional wire. Another option is to cut into the appropriate wire or use a (horrors!) crimp-on splice connector. Instead, I sometimes form my wire into a loop, put it over the appropriate device pin, and then plug the device back into its socket. The wire cannot get away and the electrical connection is made. (See pictures 1 & 2.) Obviously, you use insulated wire.

To remove, just unplug the device and remove the wire. Either solid or stranded wire can be used; I prefer solid because it makes a cleaner connection with less risk of causing a short-circuit. Solid wire is less flexible, of course, but this is supposed to be temporary, right? For a longer-than-temporary connection, cut the solid wire so it is only an inch long and splice stranded wire at that point.

If you do use this on a more permanent basis, be careful who else works on your car and document your work so you yourself remember. More than once I've pulled Klima out of its socket in this car and been surprised by my own wire ("Oh yeah, now I remember").

Mercedes uses several different sizes of pins (male and female) in its wiring. To temporarily connect to a socket with "large" pins (whatever size "large" is), I discovered that a standard "banana plug" is the perfect size. (See pictures 3 & 4.) For "small" pins, the only thing I've found to work is the matching pin from a cannibalized device or connector. I always keep a few around.

[In the 4th picture, the red/orange wire connects to a Klima pin and illuminates an LED in the dash whenever the a/c compressor is engaged (in my '95 E300D). This should work in other models with similar climate control systems]

Jeremy