DTC P0748 Pressure Control Solenoid Circuit Electrical 6.5L Diesel
Circuit Description
The Pressure Control Solenoid Valve (PC Sol. Valve) is a Powertrain Control Module (PCM) controlled device that regulates the transmission line pressure. The PCM compares the Accelerator Pedal Position (APP) Sensor voltage, engine RPM, and other inputs in order to determine the appropriate line pressure for a given load. The PCM regulates the pressure by applying a varying amperage to the PC Sol. Valve. The applied amperage varies from 0.1-1.1 amps. The PCM monitors the circuit amperage.
If 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 10-16.5 volts. |
| • | The engine must be running greater than 475 RPM for at least 7 seconds. |
| • | The difference in the commanded and the measured return amperage is greater than 0.16 amps. |
| • | All conditions met for 200 milliseconds (0.2 seconds). |
Action Taken When the DTC Sets
| • | The PCM disables the PC Sol. Valve, defaulting the transmission to maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM does not illuminate the Malfunction Indicator Lamp (MIL). |
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 for poor electrical connections at the PCM Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following problems: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | Inspect for any transmission DTCs that may have reset. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the ability of the PCM to command the PC Sol. Valve.
-
This step tests the PC Sol. Valve and the Automatic Transmission Wiring Harness Assembly for incorrect resistance.
-
When performing this step refer to Product Service Bulletin #9474L80E-07 for PC Sol. Valve Application.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data. Is the PC Act. Current reading always within the specified value of the PC Ref. Current? | 0.16 | Go to Diagnostic Aids | ||||||
Is the resistance within the specified value? | 3-7ohms | |||||||
4 |
Is the resistance within the specified range? | 3-7ohms | ||||||
5 | Replace the Automatic Transmission Wiring Harness Assembly. Refer to Interior Wiring Harness Replacement, in On-vehicle Service. Is the replacement complete? | -- | -- | |||||
6 | Measure the resistance from terminal C to the transmission case. Is the resistance less than the specified value? | 9ohms | ||||||
7 |
Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||||||
|
Important: Refer to test description Step 8 for information on component replacement. Replace the PC Sol. Valve. Refer to Pressure Regulator Replacement, in On-Vehicle Service. Is the replacement complete? | -- | -- | ||||||
9 |
Is the resistance greater than the specified value? | 9ohms | ||||||
10 |
Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||||||
11 |
Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||
13 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
DTC P0748 Pressure Control Solenoid Circuit Electrical 5.7L and 7.4L Gas
Circuit Description
The Pressure Control Solenoid Valve (PC Sol. Valve) is a Vehicle Control Module (VCM) controlled device that regulates the transmission line pressure. The VCM compares Throttle Position (TP) Sensor voltage, engine RPM, and other inputs in order to determine the appropriate line pressure for a given load. The VCM regulates the pressure by applying a varying amperage to the PC Sol. Valve. The applied amperage varies from 0.1-1.1 amps. The VCM monitors the applied amperage.
If the VCM 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 must be running more than 475 RPM for at least 7 seconds and not in fuel cut off. |
| • | The difference in the commanded and the measured return amperage is greater than 0.16 amps. |
| • | All conditions met for 200 milliseconds (0.2 seconds). |
Action Taken When the DTC Sets
| • | The VCM disables the PC Sol. Valve, defaulting the transmission to maximum line pressure. |
| • | The VCM freezes shift adapts. |
Conditions for Clearing the DTC
- A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
- The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following problems: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | First diagnose and clear any engine DTCs or TP Sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
| • | Inspect for improperly wired after-market equipment. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the ability of the VCM to command the PC Sol. Valve.
-
This step tests the PC Sol. Valve and the Automatic Transmission Wiring Harness Assembly for incorrect resistance.
-
When performing this step refer to Product Service Bulletin #9474L80E-07 for PC Sol. Valve Application.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data. Is the PC Act. Current reading always within the specified value of the PC Ref. Current? | 0.16 amp | Go to Diagnostic Aids | ||||||
Is the resistance within the specified value? | 3-7Ω | |||||||
4 |
Is the resistance within the specified range? | 3-7Ω | ||||||
5 | Replace the Automatic Transmission Wiring Harness Assembly. Refer to Interior Wiring Harness Replacement, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||
6 | Measure the resistance from terminal C to the transmission case. Is the resistance less than the specified value? | 9Ω | ||||||
7 |
Refer to Electrical Diagnosis, Section 8. Refer to Interior Wiring Harness Replacement, in On-Vehicle Service. Did you find a problem? | -- | ||||||
|
Important: Refer to Test Description Step 8 for information on component replacement. Replace the PC Sol. Valve. Refer to Pressure Regulator Replacement, in On-Vehicle Service. Is the replacement complete? | -- | -- | ||||||
9 |
Is the resistance greater than the specified value? | 9Ω | ||||||
10 |
Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||||||
11 |
Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||||||
12 | Replace the VCM. Refer to VCM Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||
13 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
