Automatic (One-Touch) Starting

The M73 and M62 engines with automatic transmissions in the E38/E39 vehicles have the One Touch Starting feature. Starting the engine requires only a momentary contact of KL 50 to engage the one touch relay. The relay will keep the starter motor engaged until the engine starts. When the engine control module receives KL 50 from the ignition switch, it powers the relay and the start signal is supplied to the starter through the EWS control module.

The engine control module keeps the relay powered until it detects engine running from the RPM sensor. Engine running is identified by:

- RPM signal > 920 with a cold engine
- RPM signal > 680 with a warm engine

If the engine fails to start after 20 seconds, the control module switches the relay OFF.

The automatic start feature prevents the continued engagement of the starter motor by continued activation of KL 50 (key being held in the KL 50 position after engine start).

The automatic start feature is dependent on the EWS systems recognition of the correct key and properly coded DME control modules.