DTC Description
This diagnostic procedure covers DTC P0748--Pressure Control Solenoid Electrical.
Circuit Description
The pressure control (PC) solenoid regulates transmission line pressure. The powertrain control module (PCM) controls the PC solenoid by applying a varying amount of current to the solenoid. The applied current can vary from 0.1 amps (high line pressure) to 1.1 amps (low line pressure).
The current is controlled by varying the duty cycle (circuit on time) expressed as a percentage. No current flow is represented as 0 percent, and approximately 60 percent indicates maximum on time, or high current flow. The PCM determines the appropriate line pressure for a given load depending on a various system inputs.
When the PCM detects a fault in the PC solenoid control or the PC solenoid, a pressure control solenoid circuit DTC sets.
Conditions for Running the DTC
| • | The system voltage is between 8.0-18 volts. |
| • | The engine is running. |
Conditions for Setting the DTC
The PC solenoid value duty cycle reaches its high limit (approximately 95 percent duty cycle) or low limit (approximately 0 percent duty cycle) for 200 milliseconds.
Conditions for Clearing the DTC
The PC solenoid circuit DTCs are Type C DTCs. Refer to Diagnostic Starting Point - Automatic Transmission for Action Taken when Type C DTCs set and Conditions for Clearing Type C DTCs.
Additional Information
| • | Refer to Transmission Component and System Description for details of the PC solenoid operation. |
| • | For and intermittent fault condition, refer to Intermittent Conditions. |
| • | Since a fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Refer to Testing for Intermittent Conditions and Poor Connections for information on electrical fault diagnosis. |
Test Description
The following numbers refer to the step numbers in the diagnostic chart.
4 This step tests the PC solenoid circuits inside the transmission for a short to ground. Check for damaged wiring or poor connections inside the transmission assembly before replacing the PC solenoid.
6 This diagnostic table only tests the PC solenoid circuits outside the transmission. Check for damaged wiring or poor connections inside the transmission assembly before replacing the PC solenoid.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Main Diagnostic Table performed? | -- | Go to Step 2 | |
2 |
Does DTC P0748 fail this ignition cycle? | -- | Go to Step 3 | Refer to Diagnostic Aids for the Pressure Control Solenoid Circuit DTCs |
3 |
Is the resistance within the specified value? | 3-7Ω | Go to Step 4 | Go to Step 6 |
4 | Using a digital multimeter, measure the resistance between each of the PC solenoid terminals on the transmission and a known ground. Does the multimeter indicate continuity? | -- | Go to Step 6 | Go to Step 5 |
5 | Test both PC solenoid control circuits for a high resistance, open circuit, short to ground, or short to voltage fault condition. Refer to Testing for Intermittent Conditions and Poor Connections for information on electrical fault diagnosis. Was any fault found and rectified? | -- | Go to Step 8 | Go to Step 7 |
6 |
Important: Check for damaged wiring (short to ground, short to voltage, high resistance, or open circuit) or poor connections inside the transmission assembly before replacing the PC solenoid. Replace the PC solenoid, Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic. Was the repair completed? | -- | Go to Step 8 | -- |
7 | Replace the PCM. Refer to Powertrain Control Module Replacement. Was the repair completed? | -- | Go to Step 8 | -- |
8 |
Do any PC solenoid circuit DTCs fail this ignition cycle? | -- | Go to Step 2 | Go to Step 9 |
9 | Using Tech 2, select the DTC Display function. Are there any DTCs displayed? | -- | System OK | |
When all diagnosis and repairs are completed, check the powertrain management system for correct operation. | ||||
