Operation CHARM: Car repair manuals for everyone.
Home >> BMW >> 2005 >> X5 (E53) L6-3.0L (M54) >> Repair and Diagnosis >> Heating and Air Conditioning >> Description and Operation >> Technical Training >> Climate Control Systems (IHKA/IHKR/IHKS Systems) >> IHKA System Inputs/Outputs >> Outputs >> IHKA/ECM Interfaces
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

IHKA/ECM Interfaces




IHKA/ECM INTERFACES







The IHKA signals the ECM when A/C is requested (KO signal), this alerts the ECM to stabilize idle speed (EML on 750iL) and compensate for the additional load. This signal is Pulse Width Modulated (5 Hz), which informs the ECM of the "get ready" request and the anticipated compressor load. On the 99 MY (E38/39/46), the A/C on signal is transmitted via the K-Bus/CAN-Bus.

On E38/39 models, the ECM sends a reply (KOREL) signal to the IHKA control module. If input conditions are correct, the IHKA will activate the A/C compressor. In addition this separate signal circuit is used to signal the IHKA to deactivate the compressor in the event that stand still full load conditions are present.

On E46/36 models, the A/C compressor relay is activated by the ECM.
pro multis · About Operation CHARM