For 1990-2009 cars

## DTC P0748 Pressure Control Solenoid Circuit Electrical 5.7L

Automatic Transmission Components VIN G
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Pressure Control Solenoid Valve (PC Sol. Valve) is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The Powertrain Control Module (PCM) controls the PC Sol. Valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1 to 1.1 amps. Low amperage (0.1 amp) indicates high line pressure. High amperage (1.1 amps) indicates low line pressure. The duty cycle of the PC Sol. Valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time (non-energized) or no current flow. Approximately 60% at idle indicates maximum ON time (energized) or high current flow. The PCM determines the appropriate line pressure for a given load by comparing the Throttle Position (TP) voltage, the engine speed and other inputs.

When the PCM detects a continuous open or short to ground in the PC Sol. Valve circuit or the PC Sol. Valve, then DTC P0748 sets. DTC P0748 is a type D DTC.

### Conditions for Setting the DTC

• | The system voltage is 8-16 volts.

• | The engine is running.

• | The PC Sol. Valve Duty Cycle reaches its high limit (approximately 95%) or low limit (approximately 0%).

### Action Taken When the DTC Sets

• | The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

• | The PC Sol. Valve is OFF.

• | The PCM freezes shift adapts from being updated.

• | DTC P0748 stores in PCM history.

### Conditions for Clearing the DTC

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

• | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

### Diagnostic Aids

• | Inspect the wiring at the PCM, the transmission 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 condition, massage the wiring harness while watching the test equipment for a change.

• | DTC P0748 may set under low voltage conditions caused by high electrical system demands.

### Test Description

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

1. This step tests the ability of the PCM to command the PC Sol. Valve.

2. This step tests the PC Sol. Valve and Automatic Transmission Wiring Harness Assembly (A/T Wiring Harness Assembly) for incorrect resistance.

#### DTC P0748 Pressure Control Solenoid Circuit -- Electrical (5.7L, VIN G)

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
2 |

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

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, then clear the DTC(s).
4. Start the engine.
5. Using the transmission output control function on the scan tool, apply 0.1 amp through 1.0 amp while observing PC Sol. Ref. Current and PC Sol. Actual Current.

Is the PC Sol. Actual Current always within the specified value of the PC Sol. Ref. Current?

0.16 amp

Go to Diagnostic Aids

Go to Step 3

3 |

1. Turn the ignition OFF.
2. Disconnect the transmission 20-way connector.
3. Install the J 39775 Jumper Harness on the transmission side of the 20-way connector.
4. Using the J 39200 Digital Multimeter (DMM) and the J 35616-A Connector Test Adapter Kit, measure the resistance between terminal C and terminal D.

Is the resistance within the specified range?

3-7 ohms

Go to Step 8

Go to Step 4

4 | Is the resistance greater than the specified value? | 7 ohms | Go to Step 5 | Go to Step 6
5 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for an open condition. Refer to General Electrical Diagnosis . Did you find an open condition? | -- | Go to Step 18 | Go to Step 10
6 | Is the resistance less than the specified value? | 3 ohms | Go to Step 7 | --
7 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for a shorted together condition. Refer to General Electrical Diagnosis . Did you find a shorted together condition? | -- | Go to Step 18 | Go to Step 10
8 | Measure the resistance from terminal C to the transmission case. Is the resistance greater than the specified value? | 250K ohms | Go to Step 11 | Go to Step 9
9 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for a short to ground condition. Refer to General Electrical Diagnosis . Did you find a short to ground condition? | -- | Go to Step 18 | Go to Step 10
10 | Replace the PC Sol. Valve. Refer to Control and Shift Solenoids Replacement . Is the replacement complete? | -- | Go to Step 20 | --
11 |

1. Disconnect the J 39775 Jumper Harness from the transmission side of the 20-way connector.
2. Reconnect the transmission 20-way connector.
3. Disconnect the C2 (blue) PCM connector.
4. Using the J 39200 DMM and the J 35616-A Connector Test Adapter Kit, measure the resistance between terminal C2-39 and C2-36.

Is the resistance within the specified range?

3-7 ohms

Go to Step 16

Go to Step 12

12 | Is the resistance greater than the specified value? | 7 ohms | Go to Step 13 | Go to Step 14
13 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for an open condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find and correct an open condition?

--

Go to Step 20

--

14 | Is the resistance less than the specified value? | 3 ohms | Go to Step 15 | --
15 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for a shorted together condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find and correct the shorted condition?

--

Go to Step 20

--

16 | Using the J 39200 DMM and the J 35616-A Connector Test Adapter Kit, measure the resistance between terminal C2-39 to ground. Is the resistance less than the specified value? | 9 ohms | Go to Step 17 | Go to Step 19
17 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for a short to ground condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find and correct the short to ground condition?

--

Go to Step 20

--

18 | Replace the A/T Wiring Harness Assembly. Refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness Replacement. Is the replacement complete? | -- | Go to Step 20 | --
19 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | Go to Step 20 | --
20 | In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear Info.
3. Start the engine and ensure that the following condition is met:

• | The engine is running.

• | The difference between the PC Sol. Valve actual return amperage and the desired amperage is less than 0.16 amp.

4. Select Specific DTC. Enter DTC P0748.

Has the test run and passed?

--

System OK

Go to Step 1

## DTC P0748 Pressure Control Solenoid Circuit Electrical 3.8L

Automatic Transmission Components VIN K
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Pressure Control Solenoid Valve (PC Sol. Valve) is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The Powertrain Control Module (PCM) controls the PC Sol. Valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1 to 1.1 amps. Low amperage (0.1 amp) indicates high line pressure. High amperage (1.1 amps) indicates low line pressure. The duty cycle of the PC Sol. Valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time (non-energized) or no current flow. Approximately 60% at idle indicates maximum ON time (energized) or high current flow. The PCM determines the appropriate line pressure for a given load by comparing the Throttle Position (TP) voltage, the engine speed and other inputs.

When the PCM detects a continuous open or short to ground in the PC Sol. Valve circuit or the PC Sol. Valve, then DTC P0748 sets. DTC P0748 is a type D DTC.

### Conditions for Setting the DTC

• | The system voltage is 10-16 volts.

• | The engine is running.

• | The PC Sol. Valve Duty Cycle reaches its high limit (approximately 95%) or low limit (approximately 0%).

### Action Taken When the DTC Sets

• | The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

• | The PC Sol. Valve is OFF.

• | The PCM freezes shift adapts from being updated.

• | DTC P0748 stores in PCM history.

### Conditions for Clearing the DTC

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

• | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

### Diagnostic Aids

• | Inspect the wiring at the PCM, the transmission 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 condition, massage the wiring harness while watching the test equipment for a change.

• | DTC P0748 may set under low voltage conditions caused by high electrical system demands.

### Test Description

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

1. This step tests the ability of the PCM to command the PC Sol. Valve.

2. This step tests the PC Sol. Valve and Automatic Transmission Wiring Harness Assembly (A/T Wiring Harness Assembly) for incorrect resistance.

#### DTC P0748 Pressure Control Solenoid Valve Circuit -- Electrical (3.8L, VIN K)

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
2 |

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

Important: Before clearing the DTC(s), 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, then clear the DTC(s).
4. Start the engine.
5. Using the transmission output control function on the scan tool, apply 0.1 amp through 1.0 amp while observing PC Sol. Ref. Current and PC Sol. Actual Current.

Is the PC Sol. Actual Current always within the specified value of the PC Sol. Ref. Current?

0.16 amp

Go to Diagnostic Aids

Go to Step 3

3 |

1. Turn the ignition OFF.
2. Disconnect the transmission 20-way connector.
3. Install the J 39775 Jumper Harness on the transmission side of the 20-way connector.
4. Using the J 39200 Digital Multimeter (DMM) and J 35616-A Connector Test Adapter Kit, measure the resistance between terminal C and terminal D.

Is the resistance within the specified range?

3-7 ohms

Go to Step 8

Go to Step 4

4 | Is the resistance greater than the specified value? | 7 ohms | Go to Step 5 | Go to Step 6
5 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for an open condition. Refer to General Electrical Diagnosis . Did you find an open condition? | -- | Go to Step 18 | Go to Step 10
6 | Is the resistance less than the specified value? | 3 ohms | Go to Step 7 | --
7 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for a shorted together condition. Refer to General Electrical Diagnosis . Did you find a shorted condition? | -- | Go to Step 18 | Go to Step 10
8 | Measure the resistance from terminal C to the transmission case. Is the resistance greater than the specified value? | 250K ohms | Go to Step 11 | Go to Step 9
9 | Inspect circuit 1228 (PPL) and circuit 1229 (LT BLU) of the A/T Wiring Harness Assembly for a short to ground condition. Refer to General Electrical Diagnosis . Did you find a short to ground condition? | -- | Go to Step 18 | Go to Step 10
10 | Replace the PC Sol. Valve. Refer to Control and Shift Solenoids Replacement . Is the replacement complete? | -- | Go to Step 20 | --
11 |

1. Disconnect the J 39775 Jumper Harness from the transmission side of the 20-way connector.
2. Reconnect the transmission 20-way connector.
3. Disconnect the C2 (clear) PCM connector.
4. Using the J 39200 DMM and the J 35616-A Connector Test Adapter Kit, measure the resistance between terminal C2-45 and C2-46.

Is the resistance within the specified range?

3-7 ohms

Go to Step 16

Go to Step 12

12 | Is the resistance greater than the specified value? | 7 ohms | Go to Step 13 | Go to Step 14
13 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for an open condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find and correct an open condition?

--

Go to Step 20

--

14 | Is the resistance less than the specified value? | 3 ohms | Go to Step 15 | --
15 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for a shorted together condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find and correct a shorted condition?

--

Go to Step 20

--

16 | Using the J 39200 DMM and the J 35616-A Connector Test Adapter Kit, measure the resistance from terminal C2-45 to ground. Is the resistance less than the specified value? | 9 ohms | Go to Step 17 | Go to Step 19
17 |

1. Inspect circuit 1228 (RED/BLK) and circuit 1229 (LT BLU/WHT) of the engine wiring harness for a short to ground condition.

Refer to General Electrical Diagnosis .

2. Repair the circuits if necessary.

Refer to Wiring Repairs .

Did you find the short to ground condition?

--

Go to Step 20

--

18 | Replace the A/T Wiring Harness Assembly. Refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness Replacement. Is the replacement complete? | -- | Go to Step 20 | --
19 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | Go to Step 20 | --
20 | In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear Info.
3. Start the engine and ensure that the following condition is met:

The difference between the PC Sol. Valve actual return amperage and the desired amperage is less than 0.16 amp.

4. Select Specific DTC. Enter DTC P0748.

Has the test run and passed?

--

System OK

Go to Step 1