TECH 1 Diagnosis - HVAC System - Manual - RPO C60

VEHICLE PREPARATION

^ Connect a jumper wire from the Heater and A/C Control Head Connector, terminal "4" or terminal "5", to the ALDL Connector, terminal "J". 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 year, key in 1990 (not 1991).

^ Proceed with climate control diagnosis.

Important:

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