GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Tracker - 2WD 🢒 DTC 🢒 DTC P0743

Circuit Description

The torque converter clutch (TCC) Solenoid engages the lock-up clutch. The powertrain control module (PCM) outputs system voltage in order to turn ON (energize) or remove voltage in order to turn OFF (to de-energize the TCC solenoid). The TCC solenoid controls the hydraulic pressure to the lock-up valve within the transmission. The TCC solenoid remains OFF in the 1st and 2nd gears. The TCC remains ON in the 3rd and 4th gears when the PCM deems appropriate. The TCC solenoid is never ON during 4L operation or when the engine coolant temperature is below 30°C (80°F).

Conditions for Setting the DTC
    • The voltage detected at PCM connector C3 terminal 16 is 2.0 V or lower when the PCM commands the TCC control solenoid ON.
    • The voltage detected at PCM connector C3 terminal 16 is 5.5 V or higher when the PCM commands the TCC control solenoid OFF.
    • Two driving cycle detection logic

Action Taken When the DTC Sets
    • DTC P0743 stores.
    • The PCM enters the fail-safe mode.
    • The malfunction indicator lamp (MIL) turns ON.

The torque converter clutch does not engage during fail-safe mode operation.

Diagnostic Aids

Inspect for the following conditions:

    • An open or shorted TCC solenoid
    • Faulty electrical circuits (open or short to ground) between the TCC solenoid and the PCM
    • A faulty PCM

The following conditions may cause an intermittent:

    • A reduced connection
    • Rubbed through wire insulation
    • A broken wire inside the insulation

Inspect the PCM harness connectors for the following conditions:

    • Backed out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Reduced terminal-to-wire connections

If DTC P0743 cannot duplicate, the information included in the Freeze Frame data may be useful in determining the vehicle operating conditions when the DTC set.

Refer to Wiring Repairs in Wiring Systems when repairing any wiring.

DTC Confirmation Procedure
  1. Turn the ignition switch to the LOCK position.
  2. Connect the scan tool to the data link connector (DLC).
  3. Turn the ignition switch ON.
  4. Use the scan tool in order to clear the following items:
    5. • DTC P0743
    • Any pending DTCs
  5. Start the engine.
  6. Warm the engine up to normal operating temperature.
  7. Shift the manual selector to DRIVE range.

    8. Remain in DRIVE range for 10 seconds.

  8. Accelerate the vehicle in DRIVE range.

    9. Continue driving for 20 seconds at 80 km/h (50 mph).

  9. Stop the vehicle.
  10. Use the scan tool to check for Scan Tool Data List for the following components:
    11. • Torque Converter Clutch (TCC) operation
    • Engine Coolant Temperature (ECT) sensor
    • Vehicle Speed Sensor (VSS) sensor
  11. Use the scan tool in order to test for a pending DTC.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. The scan tool creates an electronic copy of the data taken when the fault occurred. The information then stores in the scan tool for later reference.

    2.

  2. This step tests for proper shift points and proper TCC engagement.

    3.

  3. This step tests the total resistance of the TCC solenoid circuit.

    4.

  4. This step tests for a short to ground in the GRN/YEL wire.

    5.

  5. This step tests for an open in the GRN/YEL wire.

    6.

  6. This step inspects the transmission internal electrical harness for damage.

Step

Action

Value(s)

Yes

No

1

Was the On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 2.0L or Diagnostic System Check - Engine Controls in Engine Controls - 2.5L

2
  1. Install a scan tool.
  2. Turn ON the ignition, leaving the engine off.

Does the scan tool display any other DTC(s) in addition to DTC PO743?

--

Go to the applicable DTC table

Go to Step 3

3

  1. Perform the Upshifts and Torque Converter Clutch (TCC) Apply procedure. Refer to Road Test .
  2. With the scan tool, monitor the status of the TCC solenoid during the Road Test Procedure.

Is the procedure complete?

--

Go to Step 4

--

4

During the Road Test Procedure, did the scan tool show the TCC solenoid ON while the transmission was in fourth gear (O/D)?

--

Go to Step 5

Go to Step 11

5

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the PCM connector C3.
  3. Measure the resistance between ground and the PCM harness connector C3 terminal 8.

Is the resistance less than the specified range?

11-16.6 ohms at 24°C (75°F)

Go to Step 6

Go to Step 7

6

  1. Disconnect the TCC connector at the transmission.
  2. Measure the resistance between ground and the PCM harness connector C3 terminal 8.

Is the resistance within the specified range?

Infinite∞

Go to Step 8

Go to Step 9

7

  1. Disconnect the TCC connector at the transmission.
  2. Measure the resistance between the PCM harness connector C3 terminal 8 and the TCC connector terminal 3.

Is the resistance less than the specified range?

2 ohms

Go to Step 8

Go to Step 10

8

  1. Remove the transmission oil pan.
  2. Inspect the terminals and internal harness for damage.
  3. Replace the TCC shift solenoid if no damage exists.

Is the procedure complete?

--

Go to Step 12

--

9

Repair the short to ground in the GRN/YEL wire between the PCM and the TCC solenoid.

Is the repair complete?

--

Go to Step 12

--

10

Repair the open or the high resistance in the GRN/YEL wire between the PCM and the TCC solenoid.

Is the repair complete?

--

Go to Step 12

--

11

Replace the powertrain control module (PCM). Refer to Powertrain Control Module Replacement in Engine Controls-2.0L or Powertrain Control Module Replacement in Engine Controls-2.5L.

Is the procedure complete?

--

Go to Step 12

--

12
  1. Turn the ignition switch to the LOCK position.
  2. Reconnect any disconnected connector(s).
  3. Perform the DTC Confirmation Procedure.

Does the scan tool display any DTCs?

--

Go to the applicable DTC table

System OK