Diagnostic Aids

Check all connections, especially those at transmission pass-thru connector. If code is intermittent, see INTERMITTENTS in TESTS W/O CODES - GASOLINE article. Some slight TCC slippage is normal. The 3-2 control solenoid feedback normally oscillates on/off when duty cycle is applied.

Fig 1: Code 66 Schematic (All Models) 3-2 Control Solenoid Circuit Fault 4l60-E Transmission

Fig 2: Code 66 Flow Chart (All Models) 3-2 Control Solenoid Circuit Fault 4l60-E Transmission