DTC P0743 sets when the TCM detects an open circuit, a short to power, or a short to ground in the TCC PWM solenoid circuit for 1.5 seconds.

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Randolph Holmes
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1 Page 1 of GMC Truck GMC K Sierra - 4WD Sierra, Silverado VIN C/K Service Manual Document ID: DTC P0743 Circuit Description The torque converter clutch (TCC) solenoid is a pulse width modulated (PWM) solenoid. Pulse width modulation occurs when the signal from the transmission control module (TCM) to a solenoid is modulated at an established frequency, causing the steel check ball in the solenoid to rapidly open and close the solenoid passage. This serves to vary the output fluid pressure. DTC P0743 is a type B DTC. DTC Descriptor This diagnostic procedure supports the following DTC: DTC P0743 Torque Converter Clutch (TCC) Enable Solenoid Control Circuit Conditions for Running the DTC The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds. The TCC is commanded ON. Conditions for Setting the DTC DTC P0743 sets when the TCM detects an open circuit, a short to power, or a short to ground in the TCC PWM solenoid circuit for 1.5 seconds. Action Taken When the DTC Sets The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. DTC P0743 will be stored in TCM history. The TCM inhibits TCC engagement. The TCM freezes shift adapts. REVERSE operation is disabled. Conditions for Clearing the DTC A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure. Aids Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: A bent terminal A backed-out terminal A damaged terminal Poor terminal tension A chafed wire A broken wire inside the insulation 2016 General Motors. All rights reserved.

2 Page 2 of 5 Test Description When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. You may have to drive the vehicle in order to experience a condition. Solenoids are sensitive to battery voltage spikes and poor ground connections. The numbers below refer to the step numbers on the diagnostic table. 2. This step tests the system voltage. 6. This step tests the resistance at the TCC PWM solenoid. DTC P0743 Schematic Reference: Automatic Transmission Controls Schematics 1 Did you perform the System Check Vehicle? 2 System Check - Vehicle in Vehicle DTC Information 2 1. Install the scan tool. 2. Start the engine. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data V 3 DTC P0562 for low voltage or DTC P0563 for high voltage This diagnostic table should only be used if the DTC is currently failing. If the DTC is not active, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems until the DTC becomes active. 3. Record the DTC Freeze Frame and Failure Records. 4. Clear the DTC. 5. Using the scan tool, measure ignition voltage.

3 Page 3 of 5 Is voltage within the specified range? 3 2. Disconnect the C2 connector (RED) at the TCM. 3. Using a DMM, measure the resistance between connector C2 terminal 29 and connector C2 terminal (68 F) Is the resistance reading within the Disconnect the TCM connector C2 (RED). 3. Install the J breakout box and the J breakout box adapter. Do not connect the vehicle side C2 (RED) connector to the J Using a -volt unpowered test light, place the leads on terminals 29 and 32 of the J Turn the ignition ON, with the engine OFF. 6. Use the scan tool in Solenoid Test Mode to command the TCC PWM solenoid ON and OFF. Does the test lamp turn ON and OFF when commanded? Aids Connect the C2 (RED) connector to the TCM. 3. Disconnect the transmission 20-way connector. 4. Turn the ignition ON, with the engine OFF. Additional DTCs may set. 5. Using a -volt unpowered test light, place the leads at the engine side of the transmission 20-way connector terminals J and S. 6. Use the scan tool in Solenoid Test Mode to command the TCC PWM solenoid ON and OFF. Does the test lamp turn ON and OFF when commanded? 6 8 6

4 Page 4 of 5 2. Using a DMM, measure the resistance between terminals J and S of the transmission 20-way connector. 20 C (68 F) Aids 7 Is the solenoid resistance within the 1. Remove the oil pan. Refer to Oil Pan Replacement Remove the internal wiring harness at the TCC PWM solenoid connector. 3. Using a DMM, measure the resistance of the TCC PWM solenoid. 20 C (68 F) Is the solenoid resistance within the Repair the engine wiring harness. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair 9 Replace the AT internal wiring harness. Refer to Wiring Harness Replacement. 10 Replace the TCC PWM solenoid. Refer to Control Valve Solenoid Replacement. Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. 11 Replace the TCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Perform the following procedure in order to verify the repair: System OK 1 1. Clear the DTC. 2. Drive the vehicle under normal operating conditions. 3. Using the scan tool, monitor TCC slip speed. The TCC must engage/disengage when commanded. 4. Select Specific DTC. 5. Enter DTC P0743.

5 Page 5 of 5 Has the test run and passed?

DTC P Shift Solenoid Circuit Electrical

DTC P Shift Solenoid Circuit Electrical 1998 Pontiac Grand Prix DTC P0753 1-2 Shift Solenoid Circuit Electrical Circuit Description The 1-2 Shift Solenoid Valve (1-2 SS Valve) controls the fluid flow acting on the 1-2 and 3-4 shift valve. The