62TE

P0868-LINE PRESSURE LOW







Theory of Operation

Line pressure is measured by the Line Pressure Sensor (LPS) and regulation is achieved by changing the duty cycle of the Pressure Control Solenoid (PCS) controlled by the Transmission Control System. (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 both the engine and transmission.

The Transmission Control System calculates torque input to the transmission and uses it as the primary input to the desired line pressure calculation. This is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level during shifts and in Park and Neutral to ensure consistent shift quality. The desired line pressure is continuously being compared to the actual line pressure. If the actual line pressure is consistently lower than the target while driving, the line pressure low DTC P0868 will set.

- When Monitored:
Continuously while driving in a forward gear.

- Set Condition:
The Powertrain Control Module (PCM) continuously monitors Actual Line Pressure and compares it to Desired Line Pressure. If the Actual Line Pressure is more than 5 psi below Desired Line Pressure while the PCS duty cycle is at or near its minimum value, this DTC will set.





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

1. CHECK FOR RELATED DTCS
1. With the scan tool, read DTCs.

Is the DTC P0932 present also?

Yes

- P0932 Perform the appropriate diagnostic procedure.

No

- Go To 2

2. CHECK IF THE DTC IS CURRENT
1. With the scan tool, check the Starts Since Set counter for P0868.

NOTE: This counter only applies to the last DTC set.

Is the Starts Since Set COUNTER 2 or less?

Yes

- Go To 3

No

- Go To 10

3. CHECK THE PCM AND WIRING
1. Turn the ignition off to the lock position.
2. Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.

3. Install the Transmission Simulator 8333A and the Electronic Transmission Adapter kit.
4. On the Transmission Simulator select the "OFF" position of the "Input/Output Speed" switch.
5. Ignition on, engine not running.
6. With the scan tool, monitor the Line Pressure during the following steps.
7. Using the Transmission Simulator, set the rotary knob to each of the three line pressure positions.

NOTE: All three scan tool Line Pressure readings should be steady and ± 14 kPa or 2.0 psi (0.2 of a volt) of the reading specified on the Transmission Simulator.

Did the Line Pressure read within ± 14 kPa or 2.0 psi (0.2 of a volt) in all three positions?

Yes

- Go To 4

No

- Go To 6

4. CHECK THE LINE PRESSURE SENSOR
1. Turn the ignition off to the lock position.
2. Disconnect the Transmission Simulator 8333A and reconnect all previously disconnected connectors.
3. Install a Pressure Gauge, 0 to 2000 kPa or 0 to 300 psi to the Line Pressure test port.
4. Start the engine in park.
5. Monitor the line pressure readings of both the scan tool and the pressure gauge and compare the two readings.

Is the line pressure gauge reading within 34 kPa or 5 psi of the scan tool reading?

Yes

- Go To 5

No

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

5. CHECK FOR A PLUGGED TRANSMISSION OIL FILTER
1. Turn the ignition off to the lock position.
2. Remove and inspect the Transmission Oil Pan for excessive debris.
3. Remove and inspect the Transmission Oil Filter.

Does the Oil Pan contain excessive debris and/or is the Transmission Oil Filter plugged?

Yes

- Repair as necessary. If the Transmission Oil Filter is plugged or there is excessive debris, refer to the Service Information for the proper Hydraulic repair procedure.
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

No

- Repair internal transmission and inspect the Transmission Oil Pump and replace if necessary.
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

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




1. Disconnect the Transmission Simulator 8333A and the Electronic Transmission Adapter kit.
2. Reconnect all previously disconnected connectors except the Line Pressure Sensor/Variable Force Solenoid Assembly harness connector.
3. Ignition on, engine not running.
4. Measure the voltage of the (F856) 5-volt Supply circuit.

Is the voltage above 5.5 volts?

Yes

- Repair the (F856) 5-volt Supply circuit for a short to voltage.
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

No

- Go To 7

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




1. Turn the ignition off to the lock position.
2. Disconnect the PCM C1 harness connector and connect the PCM Pinout Box 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 the PCM Pinout Box 8815 to perform diagnosis.

3. Measure the resistance of the (F856) 5-volt Supply circuit between the Line Pressure Sensor/Variable Force Solenoid Assembly harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (F856) 5-volt Supply circuit for an open.
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

No

- Go To 8

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




1. 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 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

No

- Go To 9

9. CHECK THE (T118) PRESSURE CONTROL LINE PRESSURE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT




1. Turn the ignition off to the lock position.
2. Disconnect the Line Pressure Sensor/Variable Force Solenoid Assembly harness connector.
3. Disconnect all PCM harness connectors.
4. Measure the resistance between the (T118) Pressure Control Line Pressure circuit and all other circuits in the Line Pressure Sensor/Variable Force Solenoid Assembly harness connector.

Is the resistance below 5.0 Ohms between the (T118) Pressure Control Line Pressure circuit and any other circuit(s) in the Line Pressure Sensor/Variable Force Solenoid Assembly harness connector?

Yes

- Repair the (T118) Pressure Control Line Pressure circuit for a short to another circuit(s).
- Perform the 62TE TRANSMISSION VERIFICATION TEST. 62TE 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 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

10. CHECK THE 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 62TE TRANSMISSION VERIFICATION TEST. 62TE Transmission Verification Test.

No

- Test Complete.