HVAC System - Automatic - Electronic Controls

Trouble Code Description Table:

DTCS CURRENT AND HISTORY
The heater-A/C control stores DTCs as current or history codes. If the heater-A/C control detects a system malfunction, the heater-A/C control will only store a DTC that corresponds to that particular malfunction. If a current DTC is stored and the fault is no longer present, some DTCs will remain current until the first ignition cycle. Other DTCs will go into history when the fault is no longer present and does not require an ignition cycle. History DTCs are intermittent malfunctions and must be diagnosed differently than current DTCs. Refer to Intermittent and Poor Connections. Intermittent and Poor Conditions

DISPLAYING DIAGNOSTIC TROUBLE CODES (DTCS)
Diagnostic trouble codes can be read through the use of the scan tool. There are no provisions for flash code diagnostics. Refer to the scan tool manual for specific directions or instructions for the scan tool.

The scan tool will provide a technician with the following information:
^ Read the data list.
^ Read current and history diagnostic trouble codes.
^ Clear the diagnostic trouble codes after a repair has been completed. Make sure the scan tool contains an updated cartridge before attempting to communicate with the heater A/C control. To use the scan tool, connect it to the Data Link Connector (DLC) and turn the ignition switch to the RUN position. The scan tool reads serial data sent from the heater-A/C control serial data output terminal D12 through the splice pack SP205 and then to the DLC terminal 2.

CLEARING DIAGNOSTIC TROUBLE CODES (DTCS)
Scan Tool Method
Select DTCs for diagnostic trouble codes after DTCs have been viewed completely, scan tool will ask, CLEAR DTCs? Answer YES. Scan tool will then read. HISTORY DATA WILL BE LOST. CLEAR DTCs? Answer YES and DTCs will be cleared. DTCs cannot be cleared until all DTCs have been displayed.

Ignition Cycle Default
If no diagnostic trouble codes occur for 100 drive cycles (a drive cycle occurs when the ignition switch is turned to the RUN position, and the vehicle is driven faster than 16 km/h [10 mph]), any existing DTCs are automatically cleared from the heater-A/C control.