1995 W124 - Simultaneous Electrical Issues
 

W124 —While driving multiple accessories simultaneously lose electric power. For example, the radio turns off, windows & sunroof stop working, wipers if on stop in place and the heated seats turn off and power seats do not work all at one time. Now when I notice the SRS light coming on for a few seconds, then everything works fine but soon afterward all items no longer work again.

There is no consistent pattern except that everything works for a short duration after the "SRS" light momentarily comes on while driving and only movement and not time changes the situation. It is quite a nuisance when you park and can no longer raise up the windows or while driving the radio shuts off. The car is a 1995 E420 with 58,000 miles. I have changed the combination relay as I had erratic wiper movement which was resolved but now the wipers again have no power except for a minutes after the SRS light comes on. I have checked many ground connections and everything seems to be snug and no corrosion. Could the convenience relay be the culprit for some of the issues? Interestingly I took the convenience relay out to note any changes and the power seats still worked with it out.http://www.mbworld.org/forums/images/smilies/crazy.gif

Secondary problem is the low beams permanently do not go on, but high beams and fog lamps work fine. I checked voltage at the fuse for low beams and it read none, but high beams had normal. If with a screwdriver I touch between low and the high beam fuses, low beams will light. Could it be the current is not getting past the combination switch on the low beam circuit...thus faulty switch?

Thanks ahead for any advice.

Spin the fuses in their socket holders ..they will fool you and look fine, but will have a poor connection right at the holders.
Do it with the load On , as that helps find the connection faster...

Check the main grounds, I believe there is one behind the instrument cluster, one near the battery, and I forget where the others are on that car. You are looking for lots of brown wires screwed to the chassis. Make sure the connections are good and tight. You are losing so many things at once, it really sounds like one of those grounds is getting loose.


-tp

I have checked many ground connections already and all look good —tight and clean. Even under the console and lower instrument panel. Will keep looking. Thanks!

Has the wiring harness been replaced? Bad harness can create a lot of electrical funny business.

Yes the wiring has been replaced. This problem comes and goes.

Did you solve your problem?

replace fuse #2
 

on my 124 fuse number 2 runs the power seats, windows, sunroof and wipers....just replace it...