1995 E320 rear brake no sensor?
 

According to service manual there should be low brake warning sensors on the back brakes. Well, as I'm doing R&R on the rears, I find the brake pad has the small hole for the sensor but there are no sensors, no wiring or plug on the caliper housing. Is this normal?
Its there on the front brakes.

Yes, this is normal. Somewhere I read that only ASR equipped cars have the brake wear indicators on the rear brakes.

J. M. van Swaay

Correct. ...and also, only ASR has seperate wheel speed sensors for all four wheels.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1994-Mercedes--Benz-E3--0--Sedan-Brake&yearid=1994%40%401994&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6391%3ABT%7C5%3AMBC%7C1508%3 AED%7C10000022%40%40E320+Sedan&catid=241658%40%40Brake&subcatid=241669@@Brake+Pad+Sensor&mode=PA