DTC P0748 Pressure Control Solenoid Circuit Electrical 2.4L
Circuit Description
The PCM uses the pressure control (PC) solenoid valve in order to regulate the transmission line pressure. The PC solenoid valve consists of an electrical connector, a coil, an armature, a regulating spring, and a poppet valve. The PC solenoid valve is attached to the upper control body. The PCM compares TP voltage, fluid temperature, gear states, and other inputs in order to determine the line pressure appropriate for a given load. The PCM regulates the pressure by applying a varying amperage to the PC solenoid valve. The applied amperage varies from 0.1 amps for maximum line pressure to 1.1 amps for minimum line pressure. The PCM then monitors the amperage at the return line.
When the PCM detects a continuous open or short to ground in the PC solenoid valve circuit, or the PC solenoid valve, then DTC P0748 sets. DTC P0748 is a type D DTC.
Conditions for Running the DTC
The system voltage is 8-18 volts.
Conditions for Setting the DTC
The PC solenoid valve duty cycle is 0% or greater than 95%.
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM commands maximum line pressure (0 amps). |
| • | The PCM freezes shift adapts from being updated. |
| • | The PCM stores DTC P0748 in PCM history. |
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-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 and the PC solenoid valve 2-way connector 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. |
| • | Extended engine cranking with a weak battery could set DTC P0748. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the ability of the PCM to command the PC solenoid valve.
-
This step verifies that the automatic transmission wiring harness and the PC solenoid valve have correct resistance.
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. Using the Clear Info function erases the Failure Records from the PCM. Does the PC Sol. Actual Current amp reading differ from the PC Sol. Ref. Current amp reading by no more than the specified amount? | 0.16 amps | Go to Diagnostic Aids | ||
Is the resistance within the specified range? | 3-7 ohms | |||
4 | Is the resistance greater than the specified value? | 7 ohms | ||
5 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
6 | Inspect circuit 1228 and circuit 1229 from the transmission 20-way connector to the PC solenoid valve for being shorted together. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||
7 | Measure the resistance from terminal D to a good ground. Is the resistance less than the specified value? | 1,000 ohms | ||
8 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
9 | Replace the PC solenoid valve. Refer to Control and Shift Solenoids Replacement. Is the replacement complete? | -- | -- | |
10 |
Is the resistance less than the specified value? | 10 ohms | ||
11 | Inspect circuit 1229 from the engine 20-way connector to the PCM connector for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
12 | Using the J 35616-A , connect the J 39200 DMM from terminal D of the J 39775 to the PCM terminal C2-9 and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
13 | Inspect circuit 1229 from the engine 20-way connector to the PCM connector for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
14 | Using the J 35616-A , connect the J 39200 DMM from terminal C of the J 39775 to a good ground and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
15 | Inspect circuit 1228 from the engine 20-way connector to the PCM connector for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
16 | Using the J 35616-A , connect the J 39200 DMM from terminal C of the jumper harness to the PCM terminal C2-6 and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
17 | Inspect circuit 1228 from the engine 20-way connector to the PCM connector for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
18 | Repair the wiring as necessary. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
19 | Replace the automatic transmission wiring harness. Refer to Unit Repair. Is the replacement complete? | -- | -- | |
20 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |
21 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
DTC P0748 Pressure Control Solenoid Circuit Electrical 3.1L
Circuit Description
The PCM uses the pressure control (PC) solenoid valve in order to regulate the transmission line pressure. The PC solenoid valve consists of an electrical connector, a coil, an armature, a regulating spring, and a poppet valve. The PC solenoid valve is attached to the upper control body. The PCM compares TP voltage, fluid temperature, gear states, and other inputs in order to determine the line pressure appropriate for a given load. The PCM regulates the pressure by applying a varying amperage to the PC solenoid valve. The applied amperage varies from 0.1 amps for maximum line pressure to 1.1 amps for minimum line pressure. The PCM then monitors the amperage at the return line.
When the PCM detects a continuous open or short to ground in the PC solenoid valve circuit, or the PC solenoid valve, then DTC P0748 sets. DTC P0748 is a type D DTC.
Conditions for Running the DTC
The system voltage is 8-18 volts.
Conditions for Setting the DTC
The PC solenoid valve duty cycle is 0% or greater than 95%.
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM commands maximum line pressure (0 amps). |
| • | The PCM freezes shift adapts from being updated. |
| • | The PCM stores DTC P0748 in PCM history. |
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-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 and the PC solenoid valve 2-way connector 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. |
| • | Extended engine cranking with a weak battery could set DTC P0748. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the ability of the PCM to command the PC solenoid valve.
-
This step verifies that the automatic transmission wiring harness and the PC solenoid valve have correct resistance.
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. Using the Clear Info function erases the Failure Records from the PCM. Does the PC Sol. Actual Current amp reading differ from the PC Sol. Ref. Current amp reading by no more than the specified amount? | 0.16 amps | Go to Diagnostic Aids | ||
Is the resistance within the specified range? | 3-7 ohms | |||
4 | Is the resistance greater than the specified value? | 7 ohms | ||
5 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
6 | Inspect circuit 1228 and circuit 1229 from the transmission 20-way connector to the PC solenoid valve for being shorted together. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | ||
7 | Measure the resistance from terminal D to a good ground. Is the resistance less than the specified value? | 1,000 ohms | ||
8 |
Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||
9 | Replace the PC solenoid valve. Refer to Control and Shift Solenoids Replacement. Is the replacement complete? | -- | -- | |
10 |
Is the resistance less than the specified value? | 10 ohms | ||
11 | Inspect circuit 1229 from the engine 20-way connector to the PCM connector for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
12 | Using the J 35616-A , connect the J 39200 DMM from terminal D of the jumper harness to the PCM terminal C2-46 and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
13 | Inspect circuit 1229 from the engine 20-way connector to the PCM connector for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
14 | Using the J 35616-A , connect the J 39200 DMM from terminal C of the jumper harness to a good ground and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
15 | Inspect circuit 1228 from the engine 20-way connector to the PCM connector for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
16 | Using the J 35616-A , connect the J 39200 DMM from terminal C of the J 39775 to the PCM terminal C2-45 and measure the resistance. Is the resistance less than the specified value? | 10 ohms | ||
17 | Inspect circuit 1228 from the engine 20-way connector to the PCM connector for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was the condition found? | -- | -- | |
18 | Repair the wiring as necessary. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
19 | Replace the automatic transmission wiring harness. Refer to Unit Repair. Is the replacement complete? | -- | -- | |
20 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |
21 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
