LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mercedes Benz >> 1990 >> 560SEC >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Computerized Engine Controls >> Control Unit Operation
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Control Unit Operation

Electronic control system consists of airflow sensor position indicator (potentiometer), Electro-Hydraulic Actuator (EHA), thermo time switch, coolant temperature sensor, Electronic Control Unit (ECU), transistorized EZL ignition system, throttle valve microswitch, altitude sensor, lambda control and oxygen sensor.

Fuel metering is achieved through CIS-E injection system. System is basic CIS injection with electronic controls (E) added for mixture correction. Federal and California CIS-E control units are not interchangeable.

Spark timing is determined by ECU-controlled EZL electronic ignition system. Characteristics for various engine load conditions are stored in ignition control module.

Fig 1: 190E, 260E, 300CE, 300E & 300TE Component Locations
G94907Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Fig 2: 300SE & 300SEL Component Locations
G94908Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Fig 3: 420 & 560 Series Component Locations
G94910Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
NOTE: Components are grouped into 2 categories. The first category covers INPUT DEVICES, which control or produce voltage signals monitored by the control unit. The second category covers OUTPUT SIGNALS, which are components controlled by the control unit.