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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Intrigue 🢒 DTC 🢒 DTC P0748 Pressure Control Solenoid Circuit Electrical

Object Number: 160458 Size: MF
Automatic Transmission Components
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The pressure control solenoid valve (PC Solenoid Valve) regulates actuator feed fluid passing through the solenoid into torque signal pressure. The PCM uses a pulse width modulated signal in order to control the torque signal pressure. The PCM compares various inputs in order to determine the appropriate pressure for a given load. The PCM varies the current to the PC Solenoid Valve from 0.1-1.1 amp. An internal current monitor within the PCM provides feedback in order to determine actual PC Solenoid Valve current draw.

If the PCM detects a commanded current draw that differs from the actual current draw by more than a calibrated value, then DTC P0748 sets. DTC P0748 is a Type D DTC.

Conditions for Setting the DTC
    • The PC Solenoid Valve is enabled.
    • The system voltage is:
       - Greater than 11 volts at a low temperature -40°C (-40°F).
       - Greater than 13 volts at a high temperature 151°C (304°F).
    • The PCM commands the PC Solenoid Valve ON and the circuit voltage remains high (B+).
    • The PCM commands the PC Solenoid Valve OFF and the circuit voltage remains low (0 volts).

Action Taken When the DTC Sets
    • The PCM does not illuminate the Malfunction Indicator Lamp (MIL).
    • The PCM commands maximum line pressure.
    • The PCM freezes shift adapts.
    • The PCM stores DTC P0748 in PCM history.

Conditions for Clearing the DTC
    • A scan tool clears the DTC from the PCM history.
    • The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring.
    • The PCM 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 PCM.

Diagnostic Aids
    • Inspect the wiring at the PCM, the transmission 20-way connector, the PC Solenoid Valve connector and all other circuit connecting points 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
       - Moisture intrusion
       - Corrosion
    • When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
    • Extended cranking with a low battery could set DTC P0748.

Test Description

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

  1. This step verifies the ability of the PCM to command the PC Solenoid Valve.

    2.

  2. This step verifies that the automatic transmission wiring harness assembly (A/T Wiring Harness Assembly) and the PC Solenoid Valve have correct resistance.

    3.

  3. This step tests for a short to ground inside the transmission.

    4.

  4. This step tests circuits 1228 (PPL) and 1229 (LT BLU) of the A/T Wiring Harness Assembly for a short to ground.

    5.

  5. This step tests circuit 1229 (LT BLU/WHT) from the engine 20-way connector to the PCM for an open.

    6.

  6. This step tests circuit 1228 (RED/BLK) from the engine 20-way connector to the PCM for a short to ground.

    7.

  7. This step tests circuit 1228 (RED/BLK) from the engine 20-way connector to the PCM for an open.

DTC P0748 Pressure Control 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. Start the engine.

    3. Important: Before clearing the DTCs, use the Scan Tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the PCM.

  3. Record the DTC Failure Records.
  4. Clear the DTCs.
  5. Select Transmission Output Controls, PC Solenoid on the Scan Tool .
  6. Apply several settings from 0.1 amp through 1.1 amp and observe the Scan Tool display.

Does the PC Sol. Actual Current reading differ from the PC Sol. Ref. Current reading by more than the specified amount?

0.16 amp

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the transmission 20-way connector (additional DTCs will set).
  3. Connect the J 39775 Jumper Harness to the transmission side of the 20-way connector.
  4. Using the J 35616-A Connector Test Adapter Kit, connect a J 39200 Digital Multimeter (DMM), set to measure ohms, from terminal C to terminal D of the jumper harness.

Is the resistance within the specified range?

3-5 ohms at 20°C (68°F)

5-6 ohms at 88°C (190°F)

Go to Step 7

Go to Step 4

4

Is the resistance greater than the specified value?

6 ohms at 20°C (68°F)

7 ohms at 88°C (190°F)

Go to Step 5

Go to Step 6

5
  1. Inspect circuit 1228 (PPL) from the transmission side of the 20-way connector to the PC Solenoid Valve for an open.
  2. Inspect circuit 1229 (LT BLU) from the transmission side of the 20-way connector to the PC Solenoid Valve for an open.

Refer to General Electrical Diagnosis in Wiring Systems.

Was a condition found?

--

Go to Step 18

Go to Step 9

6

Inspect circuits 1228 (PPL) and 1229 (LT BLU) from the transmission side of the 20-way connector to the PC Solenoid Valve for a short together.

Refer to General Electrical Diagnosis in Wiring Systems.

Was a condition found?

--

Go to Step 18

Go to Step 9

7

Connect the DMM, set to measure ohms, from terminal D of the jumper harness to a good ground.

Is the resistance less than the specified value?

1000 ohms

Go to Step 8

Go to Step 10

8

  1. Inspect circuit 1228 (PPL) from the transmission side of the 20-way connector to the PC Solenoid Valve for a short to ground.
  2. Inspect circuit 1229 (LT BLU) from the transmission side of the 20-way connector to the PC Solenoid Valve for a short to ground.

Refer to General Electrical Diagnosis in Wiring Systems.

Was a condition found?

--

Go to Step 18

Go to Step 9

9

Replace the Pressure Control Solenoid Valve.

Refer to Pressure Control Solenoid Valve Replacement .

Is the replacement complete?

--

Go to Step 20

--

10

  1. Disconnect the J 39775 Jumper Harness from the transmission side of the 20-way connector.
  2. Connect the J 39775 Jumper Harness to the engine side of the 20-way connector.
  3. Disconnect PCM connector C2 (additional DTCs will set).
  4. Using the J 35616-A Connector Test Adapter Kit, connect the DMM, set to measure ohms, from terminal D of the jumper harness to a good ground.

Is the resistance less than the value specified?

10 ohms

Go to Step 11

Go to Step 12

11
  1. Inspect circuit 1229 (LT BLU/WHT) of the engine wiring harness for a short to ground.

    2. Refer to General Electrical Diagnosis in Wiring Systems.

  2. Repair the circuit if it is shorted to ground.

Was a condition found and corrected?

--

Go to Step 20

--

12

Using the J 35616-A Connector Test Adapter Kit, connect the DMM, set to measure ohms, from terminal D of the jumper harness to the PCM connector C2 terminal 46.

Is the resistance less than the value specified?

10 ohms

Go to Step 14

Go to Step 13

13
  1. Inspect circuit 1229 (LT BLU/WHT) of the engine wiring harness for an open.

    2. Refer to General Electrical Diagnosis in Wiring Systems.

  2. Repair the circuit if it is open.

Was a condition found and corrected?

--

Go to Step 20

--

14

Using the J 35616-A Connector Test Adapter Kit, connect the DMM, set to measure ohms, from terminal C of the jumper harness to a good ground.

Is the resistance less than the value specified?

10 ohms

Go to Step 15

Go to Step 16

15

  1. Inspect circuit 1228 (RED/BLK) of the engine wiring harness for a short to ground.

    2. Refer to General Electrical Diagnosis in Wiring Systems.

  2. Repair the circuit if it is shorted to ground.

Was a condition found and corrected?

--

Go to Step 20

--

16

Using the J 35616-A Connector Test Adapter Kit, connect the DMM, set to measure ohms, from terminal C of the jumper harness to the PCM connector C2 terminal 45.

Is the resistance less than the value specified?

10 ohms

Go to Step 19

Go to Step 17

17

  1. Inspect circuit 1228 (RED/BLK) of the engine wiring harness for an open.

    2. Refer to General Electrical Diagnosis in Wiring Systems.

  2. Repair the circuit if it is open.

Was a condition found and corrected?

--

Go to Step 20

--

18

Replace the Automatic Transmission Wiring Harness Assembly.

Refer to Solenoids and Wiring Harness Replacement .

Is the replacement complete?

--

Go to Step 20

--

19

Replace the PCM.

Refer to Powertrain Control Module Replacement/Programming in Engine Controls.

Is the replacement complete?

--

Go to Step 20

--

20

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • The PC Solenoid Valve enabled.
    • The system voltage:
       - Greater than 11 volts at a low temperature -40°C (-40°F).
       - Greater than 13 volts at a high temperature 151°C (304°F).
       - The PCM commands the PC Solenoid Valve ON (circuit voltage becomes low {0 volts}) then OFF (circuit voltage becomes high {B+}).
  4. Select Specific DTC. Enter DTC P0748.

Has the test run and passed?

--

System OK

Go to Step 1