Vehicle: 2003 Mercedes Benz E320
Sedan (211.065), V6-3.2L, Automatic Transmission
Problem: The high and low beam headlights
were out on the passenger side. Because of the vehicle’s age, the
owner decided to replace all four headlights. Unfortunately, the
passenger side high and low beams were still inoperative. He
brought the car to the shop for a diagnosis and repair.
The technician connected a scan tool, which revealed no
diagnostic trouble codes. Next, the Technician verified that
there was no battery power to the passenger low and high beam
headlights. At that point he called ALLDATA Tech-Assist for
The Tech-Assist consultant suggested to start by inspecting fuse
#75 (40a), which is in the front pre-fuse box, mounted in the
passenger footwell. Since the fuse checked out good, next the
consultant suggested verifying that the passenger signal
actuation module (SAM) control unit was getting full battery
voltage on terminal #5 (red) and that terminal #1 (brown) was
getting a solid ground at connector I1. Both power and ground
checked out perfect.
The next test was to check terminal #6 (yellow) for battery
voltage on low beam and terminal #2 (white/yellow) for battery
voltage on high beam at connector I3.
While testing those wires, the technician noticed that if he
removed the SAM control unit bracket, the lights would work and
when he tightened it back down, the headlights would lose power.
Upon closer inspection, he found the yellow and the white/yellow
wires were both open under the floor panel. The SAM control unit
harness was a little short and was being stretched, which caused
the wires to break inside the insulation.
Confirmed Repair: The technician repaired
both wires and rerouted the harness so there wouldn’t be and
tension on it. After the repairs, both passenger headlights
operated normally. Fixed!