Housing Assembly

IHKA E38 HOUSING ASSEMBLY







The IHKA E38 housing is very different in appearance and layout from earlier IHKA housing assemblies, but it has almost the same system components mounted inside or on it.

Significant differences from earlier IHKA housing assemblies are:

- The housing assembly mounts against a vertical area of the engine compartment/ interior bulkhead, with no parts protruding through the bulkhead.
- The housing assembly does not contain the microfilter; the filter is incorporated into the hood-mounted air intake ducting.
- No ambient temperature sensor is mounted on the E38 housing. The control panel/module obtains ambient temperature from the instrument cluster via the K-bus.
- The system control module is not mounted on the housing: it is combined with the control panel.

IHKA E38 uses ten stepper motors to position the various flaps.

The stepper motors are mounted on the housing assembly as shown:












Only the fresh air flap stepper motor is a conventional stepper motor; it is linked to the control panel/module by four circuits.

The other nine stepper motors are smart" motors; each one contains a microprocessor

The smart stepper motor used at each position has a unique part number.

All nine "smart" stepper motors share the same power, ground, and signal circuits (referred to as the M-Bus), but the circuits split into two paths at the control panel/module:







- The left side includes five motors and the connector is color-coded white.
- The right side includes four motors and is color-coded black.

The microprocessor in each motor gives it an "identity." When the control panel/module wants a specific motor to run, it "names" the motor it wants to respond and issues a command.

Since all the stepper motors share the same signal circuit, they all "hear" the command.

Each stepper motor processes the command and determines whether it should respond.

Only the stepper motor which "hears" its name follows the command.