On-Board Diagnostics

The A/C-heater control communicates on the Programmable Communication Interface Multiplex System (PCI) Bus and is fully addressable with the DRBIII(R).

The A/C-heater control's primary means of fault detection is through active and stored diagnostic trouble codes (DTCs). Active DTCs are those which currently exist in the system. The condition causing the fault must be repaired in order to clear this type of DTC. Stored DTCs are those which occurred in the system since the A/C-heater control received the last clear diagnostic info message. DTCs must be read with the DRBIII(R).

The A/C-heater control's secondary means of fault detection is through system tests. These tests include the HVAC System Test, the A/C Cooldown Test, the Actuator Circuit Test, and HVAC Door Recalibration. Refer to System Tests for a detailed description of each test.