DTC P0128 Mercedes-Benz

Description

Headlamp Control Module (HCM) checks if reverse gear (R) is engaged. In cars with an automatic transmission, the signal comes from the transmission control module (TCM). In vehicles equipped a manual transmission, the signal comes from the central electronic module (CEM). If reverse gear (R) is engaged, the lateral control shall not be activated. The diagnostic trouble code (DTC) is stored if the control module detects that: Information from transmitting control module about reverse gear (R) missing. Transmitting control module indicates a lower quality level of information than the Headlamp Control Module (HCM) accepts. The control modules test for the diagnostic trouble code (DTC) starts in the event of: Activated control module. Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.