Main Relay Control

The MS S52 control module activates the main relay when KL 15 is switched ON. This provides operating power for the control module and in addition the following systems/circuits also receive operating power from the main relay:

• Traction control module
• Fuel pump relay
• Secondary air pump relay/air pump
• E-box cooling fan
• Auxiliary oil pump solenoids
• Purge valve
• Fuel injectors
• VANOS solenoids
• Oxygen sensor heaters
• Air mass sensors
• Idle control valve

The MS S52 maintains the ground for the main relay for a short duration after the ignition has been switched off. This allows the control module to store the adoption values and any fault codes.