Operation CHARM: Car repair manuals for everyone.
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

Inputs/Ouputs



Identification:






Inputs / Outputs
1. Engine speed:
Input to the A/CCM from the ECM.
Heated windshield and backlight will be inhibited when engine speed < 50 RPM.

2. Vehicle speed:
Input from the instrument cluster.
Blower speed control to minimize the effects of ram air. Road speed compensation is inhibited when maximum cooling LO, or maximum heating HI, is selected; also inhibited in defrost mode with airflow set to maximum.
Used to determine the frequency at which the exterior temperature display is updated.

3. Coolant temperature (signal derived from ECM via instrument cluster):
Input from the heater matrix temperature sensor used to control water valve and thus vent temperatures.
Used to monitor the temperature of coolant at the heater matrix to assist the control of air outlet temperature.
Used to inhibit the blowers when heating is selected and the engine coolant temperature is below 30° C.
Is used to provide progressive increase in blower speed up to 60°C.
To inhibit the water valve and pump when the coolant temperature is = < 10°C

4. Compressor ON signal:
Input to the A/CCM from the compressor relay output.
Used to determine compressor fault conditions.