Substitute Value Operation

IHKR E36 SUBSTITUTE VALUE OPERATION

As on IHKR E34, the IHKR E36 control module will ignore an input sensor signal that is outside allowable limits and, in its place, use a substitute value that
has been programmed into memory for just this purpose.

IHKR E36 substitute values are the same as those on E34 for the left and right desired temperatures, the interior temperature sensor, the ambient temperature sensor; the left and right heater core temperature sensors, and the evaporator temperature sensor.

A significant difference for E36 vehicles is that, if the signal from the temperature mixing potentiometer is out of range, the control module assumes that the thumbwheel is set for maximum cooling of stratified air (as opposed to moderate cooling on IHKR E34 systems).

Mother significant difference for E36 vehicles is due to the fact that they do not have an auxiliary coolant pump:
- If the control module receives KI.15 voltage (ignition switch in "run"), but it doesn't receive a TD signal from the engine control module, the module pulses the water valve solenoids assuming a constant engine speed of 900 RPM.


NOTE: The E36 IHKR control module monitors KI.61 and uses the signal to determine whether or not the engine is running. If the engine isn't running (or the KI.61 signal does not reach the control module), the control module will not activate the rear window defroster relay, the a/c compressor relay, or the
auxiliary fan relay.