Power management

The battery condition calculated in the Advanced Power Management (APM) module has a substantial effect on the MSA. The objective is to ensure a reliable engine start following a defined downtime based on the status of the onboard electrical system. The APM monitors the following data:

Charge state of battery
Battery temperature
Voltage dip on engine start
Power requirement of switched-on consumer units

The results of these calculations can either disable an engine stop request or enable an engine start request from the MSA. Excessive power consumption must be avoided when the engine is off. This is why the APM either deactivates all major consumers of electrical power or reduces their consumption rates whenever Terminal 15 is ON but the engine is OFF. The displays remain active.

The following consumers of electrical power are affected:

Heated rear window
Mirror heating
Seat heating
Heater blower

IMPORTANT: Automatic starts remain possible!

If the battery's charge status falls below a specific threshold following an engine stop initiated by the MSA, the MSA will respond by restarting the engine without any action on the part of the driver.

Note for Service department:

General notes

The MSA is operational only under specific conditions (see operating conditions). These conditions should always be assessed in response to customer complaints.

Automatic deactivation of Terminal 15 starting in 03/2007 on vehicles with automatic engine start-stop function (MSA - option 1CC)!

Terminal 15 is switched off automatically by the signal from the door contact when the driver's door is opened or closed (engine OFF). Terminal 15 can be permanently switched on again by subsequently pressing the Start-Stop button. Perform this process before programming or diagnosing a vehicle.