545RFE Automatic Transmission
P0935-LINE PRESSURE SENSOR CIRCUIT HIGH
For a complete wiring diagram Refer to Diagrams/Electrical Electrical Diagrams
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 ignition on and engine running.
- Set Condition:
This DTC will set if the monitored Line Pressure Sensor voltage is greater than or equal to 4.75 volts for the period of 0.18 seconds
Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure
Diagnostic Test
1. CHECK TO SEE IF DTC IS CURRENT
With the scan tool, Check the STARTS SINCE SET counter for P0935.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?
Yes
- Go To 2
No
- Go To 6
2. PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Starter Relay.
NOTE: Removal of the Starter Relay is to prevent a Transmission, NO RESPONSE, condition and disable the starter.
Install the Transmission Simulator, Miller tool #8333.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure.
Using the Transmission Simulator, set the rotary switch to each of the 3 line pressure positions.
NOTE: The readings should be within ±14 kPa or 2.0 PSI on the scan tool of the pressure reading specified on Transmission Simulator.
Does the 3 line pressures on the scan tool match the Line pressure readings on the Transmission Simulator?
Yes
- Replace the Line Pressure Sensor.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No
- Go To 3
3. (K900) SENSOR GROUND CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333.
Disconnect the PCM C2 harness connector and connect Miller tool #8815.
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 Miller tool #8815 to perform diagnosis.
Measure the resistance of the (K900) Sensor Ground circuit from the Line Pressure Sensor harness connector to the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Yes
- Repair the (K900) Sensor Ground circuit for an open.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No
- Go To 4
4. (T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT OPEN
Disconnect the PCM C4 harness connector and connect Miller tool #8815.
Measure the resistance of the (T38) Line Pressure Sensor Signal circuit from the Line Pressure Sensor harness connector to the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Yes
- Repair the (T38) Line Pressure Sensor Signal circuit for an open.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No
- Go To 5
5. (T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
Remove the Transmission Control Relay.
Connect a jumper wire between the (A104) Fused B+ circuit and the (T16) Transmission Control Relay Output circuit in the Transmission Control Relay connector.
Ignition on, engine not running.
Measure the voltage of the (T38) Line Pressure Sensor Signal circuit.
Is the voltage above 5.5 volts?
Yes
- Repair the (T38) Line Pressure Sensor Signal circuit for a short to voltage.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
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 the PCM. With the scan tool, perform QUICK LEARN.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
6. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorted and open circuits.
With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.
Where there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No
- Test Complete.