GM Service Manual Online
For 1990-2009 cars only

A wiring harness electrically connects the PCM to various sensors, solenoids, and relays within the system. Many of the connectors used are environmentally protected. These connectors are called WEATHER PACK connectors.

Important: Do not back probe WEATHER PACK type connectors.

You will often be required to take electrical readings at these connectors during system diagnosis in order to observe system performance. Whenever you are required to separate a connector, take care not to damage the pins or terminals.

Additional DTCs will set whenever you disconnect the transmission external connector from the engine wiring harness. Clear these DTCs after reconnecting the external connector. Use J 39775 jumper harness in order to aid in diagnosis of the transmission wiring and system components. Refer to Electrical Connector .