P0934

P0934-LINE PRESSURE SENSOR CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure Sensor (LPS). The desired line pressure is continuously being compared to the actual line pressure and is regulated by electronically changing the duty cycle of the Pressure Control Solenoid (PCS). (5% duty cycle = solenoid off = max line pressure, 62% duty cycle = solenoid on = min line pressure).

The Transmission Control System calculates the desired line pressure based on inputs from the transmission and engine. A calculated torque input to the transmission is used as the primary input of the desired line pressure calculation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931 kPa (120 to 135 psi) during shifts and in Park and Neutral to ensure consistent shift quality.

The monitored Line Pressure Sensor voltage should always be between 0.35 and 4.75 volts. Any monitored voltages outside these parameters indicate an Line Pressure Sensor or wiring problem and will cause either DTC P0934 or P0935 to set.

- When Monitored:
Continuously with the ignition on and engine running.

- Set Condition:
This DTC will set when the monitored Line Pressure Sensor voltage is less than or equal to 0.35 of a volt for 0.18 of a second.





Always perform the Pre-Diagnostic Troubleshooting Procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. CHECK IF THE DTC IS CURRENT
1. With the scan tool, read DTCs.

Is the status Active or is the Starts Since Set counter 2 or less for this DTC?

Yes

- Go To 2

No

- Go To 7

2. CHECK PCM AND WIRING
1. Turn the ignition off to the lock position.
2. Remove the Starter Relay.

CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.

WARNING: The Starter Relay must be removed from the PDC. Failure to do so may result in possible serious or fatal injury.

NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.

3. Install the Transmission Simulator 8333.
4. Ignition on, engine not running.
5. With the scan tool, under Transmission Sensors, monitor the Line Pressure.
6. Using the Transmission Simulator, set the rotary switch to each of the 3 line pressure positions.

NOTE: The readings should be within ±14 kPa (2.0 psi) or 0.1 volts on the scan tool to the pressure readings specified on Transmission Simulator.

Does the Line Pressure on the scan tool match the line pressures on the Transmission Simulator?

Yes

- Replace the Line Pressure Sensor.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 3

3. CHECK THE (T38) LINE PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off to the lock position.
2. Disconnect the PCM C4 harness connector and connect the PCM Pinout Box 8815.
3. Disconnect the Transmission Simulator 8333.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box 8815 to perform diagnosis.

4. Measure the resistance between ground and the (T38) Line Pressure Signal circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (T38) Line Pressure Signal circuit for a short to ground.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 4

4. CHECK THE (T38) LINE PRESSURE SIGNAL CIRCUIT FOR AN OPEN




1. Measure the resistance of the (T38) Line Pressure Signal circuit between the Line Pressure Sensor harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (T38) Line Pressure Signal circuit for an open.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 5

5. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN




1. Disconnect the PCM C1 harness connector and connect the PCM Pinout Box 8815.
2. Measure the resistance of the (F856) 5-volt Supply circuit between Line Pressure Sensor harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (F856) 5-volt Supply circuit for an open.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 6

6. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND




1. Disconnect the PCM C1 harness connector and connect the PCM Pinout Box 8815.
2. Measure the resistance between ground and the (F856) 5-volt Supply circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (F856) 5-volt Supply circuit for a short to ground.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the PCM. With the scan tool, perform Quick Learn. Quick Learn Procedure
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

7. CHECK WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Where there any problems found?

Yes

- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Test Complete.