Part 1 of 3, Torque Converter Clutch Solenoid Circuit Diagnosis

Trans Gear Switch And Torque Converter Clutch Solenoid Circuit Diagram:

CIRCUIT DESCRIPTION
The TCC solenoid gets battery power (through the TCC portion of the brake switch) when the ignition is turned "ON", and becomes energized (TCC engages) when the PCM completes the driver circuit to ground (circuit 422). The PCM will energize the TCC solenoid to engage the TCC when the following conditions exist:
^ Engine is at running temperature and system is operating in "closed-loop"
^ Vehicle speed greater than approx. 28 mph (45 kph)
^ Throttle position sensor voltage signal constant (indicating light load cruise condition)
^ Brake pedal not depressed (brake switch closed)


TEST DESCRIPTION

Chart C-8B, Torque Converter Clutch (TCC) Electrical Diagnosis (4T60 Trans - 1 Of 3):

Numbers below refer to circled numbers on diagnostic chart.
1. This test checks the functional operation of the TCC circuit.
2. This test checks the TCC control driver in the PCM.
3. This step confirms that there is battery power to terminal A of the trans connector.
4. This step confirms that the PCM is able to operate the TCC.

DIAGNOSTIC AIDS
A "SCAN" Tool indicates when the PCM has turned the TCC solenoid "ON". It does not indicate whether or not the TCC actually engaged. To determine if the TCC is actually engaging, check for drop in engine speed when the "SCAN" tool indicates the solenoid has turned "ON".