For 1990-2009 cars
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

### Circuit Description

The Pressure Control Solenoid is inside of the transmission adapter case. The pressure solenoid makes allows for the TCM to optimize the line pressure in the transmission for various driving conditions.

Pressure regulation depends on heavily on throttle position. The TCM receives throttle position from the ECM. This data is part of the PWM encoded ECM Data Signal to the TCM. This signal processes in the TCM which adjusts the transmission line pressure.

Occasionally during normal operation, the Pressure Control Solenoid is cycled to prevent the spool valve from becoming stuck. The cycling finishes without a significant affect on the line pressure.

The Pressure Control Solenoid is supplied power via the Transmission Power Relay (internal to the TCM). The TCM controls the solenoid by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. For this particular component, the TCM monitors the Current draw in order to monitor the circuit operation. When the TCM is commanding the Pressure Control Solenoid on, the control circuit current should be high (about 1.2 A). When the TCM is commanding the Pressure Control Solenoid off, the current on the circuit should be low (less than 100 mA). If the fault detection circuitry senses a current other than what is expected, this DTC will set.

### Conditions For Running The DTC

Tests continuously

### Conditions for Setting the DTC

A short to ground, open circuit, or short to battery voltage detected on the control circuit.

### Action Taken When the DTC Sets

• | The MIL/STL will not illuminate.

• | The TCM memory stores the DTC at the time of the first failure.

### Conditions for Clearing the MIL/DTC

• | A History DTC clears after forty consecutive warm-up cycles if no failures are present by this or any other non-emission related diagnostic.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the TCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

• | Poor connections at the TCM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure.

• | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help to locate the fault.

### Test Description

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

1. This step will determine if the adapter case connector is disconnected or possibly loose.

2. Listen for an audible click when the solenoid operates. Ground the circuit repeatedly if necessary.

3. If the PC solenoid valve checks out OK and no condition is found with the connections at the TCM, check the wiring and connections closely. If no condition is found, the TCM may be the cause of the condition.

#### DTC P0748 PC 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 OBD System Check in Engine Controls
2 |

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

Important: Before clearing the DTC, use the Scan Tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the ECM/TCM.

3. Record the DTC Failure Records.
4. Clear the DTC.
5. Turn the ignition switch to the OFF position.
6. Disconnect the TCM connector.
7. Disconnect the 4-way transmission adapter case connector.
8. Using the J 39200 digital multimeter (DMM) and the J 35616-A connector test adapter kit, measure the resistance between terminal 52 of the TCM connector and terminal B of the 4-way transmission adapter case connector.

Is the resistance lower than the specified value?

1.5 Ω

Go to Step 3

Go to Step 8

3 | Measure the resistance from terminal 52 of the TCM connector to ground. Is the resistance greater than the specified value? | 250K Ω | Go to Step 4 | Go to Step 9
4 | Measure for the presence of voltage at terminal 52 of the TCM connector. Is voltage measured? | -- | Go to Step 10 | Go to Step 5
5 | Measure the resistance between terminal 5 of the TCM connector and terminal C of the 4-way transmission adapter case connector. Is the resistance lower than the specified value? | 1.5 Ω | Go to Step 6 | Go to Step 11
6 | Measure the resistance from terminal 5 of the TCM connector to ground. Is the resistance greater than the specified value? | 250K Ω | Go to Step 7 | Go to Step 12
7 | Measure for the presence of voltage at terminal 5 of the TCM connector. Is voltage measured? | -- | Go to Step 13 | Go to Step 14
8 |

1. Inspect circuit FY740 (BLK/PPL) for an open condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find an open?

--

Go to Step 22

Go to Diagnostic Aids

9 |

1. Inspect circuit FY740 (BLK/PPL) for a short to ground condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find a short to ground condition?

--

Go to Step 22

Go to Diagnostic Aids

10 |

1. Inspect circuit FY740 (BLK/PPL) for a short to voltage condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find a short to voltage condition?

--

Go to Step 22

Go to Diagnostic Aids

11 |

1. Inspect circuit RA741 (GRY/RED) for an open condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find an open condition?

--

Go to Step 22

Go to Diagnostic Aids

12 |

1. Inspect circuit RA741 (GRY/RED) for a short to ground condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find a short to ground condition?

--

Go to Step 22

Go to Diagnostic Aids

13 |

1. Inspect circuit RA741 (GRY/RED) for a short to voltage condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find a short to voltage condition?

--

Go to Step 22

Go to Diagnostic Aids

14 | Measure the resistance between terminal B and terminal C at the transmission side of the 4-way transmission adapter case connector. Is the resistance within the specified range? | 3.5-5.5 Ω | Go to Step 17 | Go to Step 15
15 | Is the resistance greater than the specified value? | 5.5 Ω | Go to Step 18 | Go to Step 16
16 | Is the resistance less than the specified value? | 3.5 Ω | Go to Step 19 | --
17 | Measure the resistance between terminal B to ground. Is the resistance greater than the specified value? | 250K Ω | Go to Diagnostic Aids | Go to Step 19
18 |

1. Inspect circuit FY740 (BLUE) and circuit RA741 (BROWN) of the internal transmission wiring harness for an open condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find an open condition?

--

Go to Step 20

Go to Step 21

19 |

1. Inspect circuit FY740 (BLUE) and circuit RA741 (BROWN) of the internal transmission wiring harness for a shorted condition.

Refer to General Electrical Diagnosis in Wiring Systems.

2. Repair the circuit if necessary.

Refer to Wiring Repairs in Wiring Systems.

Did you find a shorted condition?

--

Go to Step 20

Go to Step 21

20 | Replace the internal transmission wiring harness Refer to Control Valve Body . Is the replacement complete? | -- | Go to Step 22 | --
21 | Replace the pressure control solenoid valve. Refer to Converter Clutch Solenoid . Is the replacement complete? | -- | Go to Step 22 | --
22 | Perform the following procedure in order to verify the repair.

1. Select DTC.
2. Select Clear Info.
3. Start the engine.

Is DTC P0748 set?

--

Go to Step 1

System OK