W124 Electrical Option Connector "X30"

[Jeremy5848]

Did you know that all W124 models have in the driver's footwell an electrical option connector? If you know all about it then you need to read no further. This connector is something every DIYer needs to know about because it makes DIY projects easier. This connector will be used in my next DIY project posted here so keep it in mind.

The electrical option connector, variously called a "coupler strip" (in EPC) or "X30" (in ETM) or "connector block" (in FSM) is a block of nine sets of five power terminals that are available for connecting accessories. The connections include switched and continuous power, illumination, and ground. Most cars will have at least some of the connections already in use -- in my '95 E300, five are in use leaving me with four for my projects. Connection to this block is as simple as plugging in a connector (part numbers later); the hard part is getting at the block if you've never done it before. Here's how.





To get at connector X30, first move the driver’s seat back as far as it will go. Next, remove the carpeting until you’re down to bare floor. You now see the plastic kick panel that lines the left side of the driver’s footwell and forms the “dead pedal” on which you rest your left foot. This plastic panel is held by two fasteners and a hidden Phillips screw. You must pull off some of the door edging to get at the screw. The two plastic fasteners can be popped off with a couple of plastic pry tools. With the fasteners removed, the panel can be pulled down and away from the body of the car.





Notice the hook on the back of the kick panel. You must pull the panel back until the hook comes out of its hole in the car body before you can remove the panel.





The hook goes in the hole shown by the red arrow in this picture.





A picture of the removed kick panel. It’s all one piece!





Now you can see connector X30. The big cable running down and out of the picture to the right is for the emergency brake. It is stiff and a little in the way; releasing the brake allows the cable to flex and stay out of the way. The cover on X30 can be pulled off easily – no screws. Now you can see all of the connections.





The nine rows are identical. Any option can plug into any one of the rows. The plug is called “Pin bushing housing (multiway connector),” part number 013 545 32 28 and the little metal pins (female) that go inside are called “round pin bushing (2.5 mm),” part number 002 545 99 26. Note that this plug is identical to the one that connects to the outside temperature display in your instrument cluster (except the early version with four pins). You may be able to get these connectors for cheap in a junkyard, otherwise PeachParts can get them for you.





Here’s the diagram of the connector (from FSM, “Service manual / Chassis and Body / Series 124, Volume 1” section 54 [electrical system] page 152) with notes made by me. The “position 1”-type notes refer to the ignition switch; “position 1” is Accessory and “position 2” is “Run.” (You knew that, right?) Pin 1 is “hot” all the time. Be careful poking around it with metal tools; better yet, disconnect the battery or pull Fuse “C.”

There are other “consumers” using fuses “A,” “B,” and “C.” For accessories that draw large amounts of current you will want a separate battery connection with its own fuse. For example, in many/most W124s, Fuse “C” in some cars powers the alarm, the central locking system, the power antenna, the courtesy and trunk lamps, and possibly (depending on model-year) the radio/CD player. The “budget” for this fuse is thus 16 Amps less what the other accessories have already spoken for. Different models may have different accessories so check the card in your fuse box and see what accessories are already plugged into X30.

Pin 4 Illumination: Device “N40” refers to the transistor circuit that allows the rheostat in the instrument cluster to control more lamps without burning out. N40 is powered by Fuse 9, which is only 8 Amps. Don’t overload it.

Be conservative and think before increasing the size of one of these fuses. There may be a safer way. Check your fuse box listing for under-used or unused fuses and run a new wire rather than risk an overload.

Jeremy