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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Safari - 2WD 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 4L60-E 🢒 DTC P0740 TCC Enable Solenoid Circuit Electrical

Object Number: 368597 Size: MF
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The torque converter clutch (TCC) solenoid valve is an electrical device that is used with the torque converter clutch pulse width modulation (TCC PWM) solenoid valve in order to control TCC apply and release. The TCC solenoid valve attaches to the transmission case assembly extending into the pump cover. The TCC solenoid valve receives ignition voltage through circuit 1020. The vehicle control module (VCM) controls the solenoid by providing the ground path on circuit 422. The VCM monitors the throttle position (TP) voltage, the vehicle speed, and other inputs in order to determine when to energize the TCC solenoid valve.

When the VCM detects a continuous open or a short to ground in the TCC solenoid valve circuit or in the TCC solenoid valve, then DTC P0740 sets. DTC P0740 is a type A DTC.

Conditions for Running the DTC
    • The system voltage is 10-19 volts.
    • The engine speed is greater than 450 RPM for 5 seconds.
    • The engine is not in fuel cutoff.

Conditions for Setting the DTC

DTC P0740 sets if either of the following conditions occurs for 5 seconds:

    • The VCM commands the solenoid ON and the voltage input remains high (B+).
    • The VCM commands the solenoid OFF and the voltage input remains low (0 volt).

Action Taken When the DTC Sets
    • The VCM illuminates the malfunction indicator lamp (MIL).
    • The VCM inhibits TCC engagement.
    • The VCM inhibits 4th gear if the transmission is in hot mode.
    • The VCM freezes shift adapts from being updated.
    • The VCM stores DTC P0740 in VCM history.

Conditions for Clearing the MIL/DTC
    • The VCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
    • A scan tool clears the DTC from VCM history.
    • The VCM clears the DTC from VCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    • The VCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the VCM.

Diagnostic Aids
    • Inspect the wiring at the VCM, the transmission connector and all other circuit connecting points for the following conditions:
       - A backed out terminal
       - A damaged terminal
       - Reduced terminal tension
       - A chafed wire
       - A broken wire inside the insulation
       - Moisture intrusion
       - Corrosion
    • When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
    • With the TCC engaged, the TCC slip speed should be -20 to +50 RPM.

Test Description

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

  1. This step tests for voltage to the solenoid.

    2.

  2. This step tests the ability of the VCM and wiring to control the ground circuit.

    3.

  3. This step tests the resistance of the TCC solenoid valve and the automatic transmission (A/T) wiring harness assembly.

DTC P0740 TCC Enable Solenoid Circuit Electrical

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls

2
  1. Install the Scan Tool .
  2. With the engine OFF, turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the VCM.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.

Are any of the following DTCs also set?

    • P0753
    • P0758
    • P0785
    • P1860

--

Go to Step 3

Go to Step 4

3
  1. Inspect the TRANS fuse.
  2. If the fuse is open, inspect the following components for a short to ground condition:
    3. • Circuit 1020 (PNK)
    • The solenoids
    • The A/T wiring harness assembly
    • Refer to General Electrical Diagnosis in Wiring Systems.
  3. Repair the circuit, the solenoids and the harness if necessary.

    4. Refer to Wiring Repairs in Wiring Systems.

Did you find a short to ground condition?

--

Go to Step 12

Go to Step 4

4

  1. Turn the ignition switch OFF.
  2. Disconnect the transmission 20-way connector (additional DTCs may set).
  3. Install the J 39775 jumper harness on the engine side of the 20-way connector.
  4. With the engine OFF, turn the ignition switch to the RUN position.
  5. Connect a test lamp from cavity E of the J 39775 jumper harness to ground.

    6. Refer to Automatic Transmission Inline Harness Connector End View .

Is the test lamp ON?

--

Go to Step 6

Go to Step 5

5

Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics in Wiring Systems for complete circuit distribution.

Repair the open or short to ground in ignition feed circuit 1020 (PNK) to the TCC solenoid valve.

Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 12

--

6

  1. Install the test lamp from cavity E to cavity T of the J 39775 jumper harness.
  2. Using the transmission output control function on the scan tool, command the TCC solenoid valve ON and OFF three times.

Does the test lamp turn ON when the TCC solenoid valve is commanded ON, and OFF when commanded OFF?

--

Go to Step 8

Go to Step 7

7
  1. Inspect circuit 422 (TAN/BLK) of the engine wiring harness for an open, short to ground or short to power condition.

    2. Refer to General Electrical Diagnosis in Wiring Systems.

  2. Repair the circuit if necessary.

    3. Refer to Wiring Repairs in Wiring Systems.

Did you find an open, short to ground or short to power condition?

--

Go to Step 12

Go to Step 9

8

  1. Install the J 39775 jumper harness on the transmission side of the 20-way connector.
  2. Using the J 39200 digital multimeter (DMM) and the J 35616-A connector test adapter kit, measure the resistance between terminals T and E.

    3. Refer to Automatic Transmission Inline Harness Connector End View .

Is the resistance within the specified range?

21-33 ohms

Go to Step 10

Go to Step 11

9

Replace the VCM.

Refer to VCM Replacement/Programming in Engine Controls.

Is the replacement complete?

--

Go to Step 12

--

10
  1. Measure the resistance between terminal E and ground.
  2. Measure the resistance between terminal T and ground.

Are both readings greater than the specified value?

250 K ohms

Go to Diagnostic Aids

Go to Step 11

11

Replace the A/T wiring harness assembly (this includes the TCC solenoid valve).

Refer to TCC PWM Solenoid, TCC Solenoid, and Wiring Harness.

Is the replacement complete?

--

Go to Step 12

--

12

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Drive the vehicle in D4 with the TCC ON and OFF. Ensure that the following conditions are met:
    4. • The VCM commands the TCC solenoid valve ON, and the voltage input drops to zero.
    • The VCM commands the TCC solenoid valve OFF, and the voltage input increases to B+.
    • All conditions met for 5 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0740.

Has the test run and passed?

--

System OK

Go to Step 1