Controls System - HVAC System - Electronic

Diagnosis for this system is based on Diagnostic Trouble Codes (DTCs) stored in the HVAC Control Head. When a DTC has been stored the MODE Indicator (LED) of the current mode will flash. Three dashes will be displayed on the HVAC Control Head if the Programmer fails. For DTC diagnostics, refer to Computer and Control Systems. Testing and Inspection

TECH 1 DIAGNOSIS
Vehicle Preparation
^ Connect a jumper from the Heater/Vent/Air Conditioning (HVAC) Control Head Connector, terminal "4" or terminal "5", to the DLC Connector, terminal "14." Insert the jumper through the back (wire entry side) of each connector.
^ Install the Tech 1 using the Body Systems Cartridge. When the Tech 1 asks for the model, key in 1990 (not 1996).
^ Proceed with climate control diagnosis

IMPORTANT: To prevent future data line communication problems, remove the jumper wire after diagnosis.