Vehicle: 2008 Mercedes Benz E 350 Sedan (211.056), V6-3.5L (272.964)
Problem: The E 350 sedan was brought to the shop because a red warning message regarding the charging system was intermittently being displayed in the instrument panel cluster (IPC).
Case Details: Scanning the system revealed the two diagnostic trouble codes (DTCs) listed below. The technician also noted that intermittently, there was only 11.6 Volts at the battery while the engine was running.
0365, P0620 – OPERATIONAL FAULT OF COMPONENT G2 (GENERATOR) 1337 – ALTERNATOR SERIAL INTERFACE
The technician was advised by an ALLDATA Tech-Assist consultant to check the voltage at the main lug of the alternator. If the voltage was 11.6 volts, the technician should check for a voltage signal input at the ME_SFI (PCM) connector 1, pin 45 (alternator signal to PCM). If pin 45 measure less than 11.6 volts, the technician needed to check the wire integrity from the ME-SFI connector 1, pin 45 to the alternator pin 1 (LIN bus line). If there was 0 volts, the technician would need to trace down the open circuit.
During his testing, the technician found that there was 0 Volts at the alternator lug. He traced the wiring to the pre-fuse box (F32) in the passenger’s footwell. Everything seemed to be in good condition and all the connections were tight. Then he checked the battery lead (black wire) to the pre-fuse box. It was loose.
Confirmed Repair: The technician repaired the open wire, cleared the DTC, cycled the seat back and forth a few times and test drove the vehicle. The air bag light did not return. Problem solved!