20
2001 model year changes
REST Function
The REST function continues to operate as usual except that the MAX button has taken the
place of the REST button. Activation criteria continues to be:
Ignition “OFF” or in KL R.
“MAX” button pressed.
Outside temperature below 60
o F.
Coolant temperature above 80o C.
Battery voltage above 11.4V.
The REST feature operates as previously.
Diagnostics
The IHKA IV diagnosis has been upgraded to the E46 style diagnostic program.
Solar Sensor
The IHKA IV integrates the solar sensor into the
calculation used to automatically regulate the
interior vehicle temperature. The sensor is
located in the right side defrost outlet.
In the case of a very sunny day, the interior
warms faster than the control unit can compen-
sate for. Similar is true if the weather suddenly
becomes overcast.
The input of the solar sensor in the E39 can
affect the operation of:
Blower setting
Air distribution to center vent
Because the E39 IHKA IV is a dual zone system. the solar sensor housing contains two
photo-resistors that measure solar radiation on the left and right halves of the interior.
(Please refer to the Solar Sensor module in the 2000
Systems Diagnosis training course ST 039 for a com-
plete description of the solar sensor operation and
diagnosis)
Solar Sensor
Two photo-resistors
inside of housing
