Dodge Ram Truck 1500-2500-3500. Manual — part 1623
P0869-LINE PRESSURE HIGH (CONTINUED)
For the Transmission circuit diagram (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE -
SCHEMATICS AND DIAGRAMS).
For a complete wiring diagram Refer to Section 8W
•
When Monitored:
Continuously while driving in a forward gear.
•
Set Condition:
The PCM continuously monitors Actual Line Pressure. If the Actual Line Pressure reading is greater than the
highest Desired Line Pressure ever used in the current gear, while the Pressure Control Solenoid duty cycle is
at or near its maximum value (which should result in minimum line pressure), the DTC will set.
Possible Causes
(F856) 5-VOLT SUPPLY CIRCUIT OPEN
LINE PRESSURE SENSOR CONNECTION
(T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT OPEN
(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND
(T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT SHORT TO GROUND
ITRANSMISSION CONTROL RELAY OUTPUT CIRCUIT
LINE PRESSURE SENSOR
STUCK OR STICKING MAIN REGULATOR VALVE
POWERTRAIN CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING).
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 827 or 931kPa (120 or 135 PSI) 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 pres-
sure is consistently higher than the highest desired line pressure ever used in the current gear, the line pressure
high DTC P0869 will set.
Diagnostic Test
1.
CHECK FOR RELATED DTC’S
With the scan tool, check for other Transmission DTC’s
Is the DTC P0932 or P0888 present also?
Yes
>> Refer to the Transmission category and perform the appropriate symptom.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Go To 2
21 - 424
AUTOMATIC TRANSMISSION - 545RFE - ELECTRICAL DIAGNOSTICS
DR/DH
P0869-LINE PRESSURE HIGH (CONTINUED)
2.
CONDITION P0869 PRESENT
With the scan tool, check the STARTS SINCE SET counter for P0869.
Is the STARTS SINCE SET COUNTER 2 or less?
Yes
>> Go To 3
No
>> Go To 10
3.
CHECK LINE PRESSURE SENSOR CONNECTION
Ignition on, engine not running.
With the scan tool, monitor the Transmission Line Pressure.
Firmly push the Line Pressure Sensor harness connector inward towards the Transmission.
Did the Line Pressure change to about 207 kPa or 30 PSI when the sensor connector was pushed?
Yes
>> Disconnect and properly reconnect the Line Pressure Sensor connector. Inspect terminals and repair as
necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Go To 4
4.
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.
With the Transmission Simulator select the
9
OFF
9
position on the
9
Input/Output Speed
9
switch.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure during the following step.
Using the Transmission Simulator, set the rotary switch to each of the 3 line pressure positions.
NOTE: All three scan tool Line Pressure readings should be steady and ±14 kPa or 2.0 PSI of the reading
specified on the Transmission Simulator.
Did the Line Pressure read within ±14 kPA or 2.0 PSI in all three positions?
Yes
>> Go To 5
No
>> Go To 6
DR/DH
AUTOMATIC TRANSMISSION - 545RFE - ELECTRICAL DIAGNOSTICS
21 - 425
P0869-LINE PRESSURE HIGH (CONTINUED)
5.
CHECK LINE PRESSURE SENSOR CALIBRATION
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333 and reconnect all previously disconnected connectors.
Install the Line Pressure Adaptor, Miller tool #8259, and Pressure Gauge, Miller tool #C-3293, 0 to 2000 kPa or 0
to 300 PSI.
Start the engine in park.
Monitor the Line Pressure readings on the scan tool and the pressure gauge.
Compare the Line Pressure readings between the scan tool and the pressure gauge.
Is the pressure gauge reading within 34 kPa or 5 PSI of the scan tool reading?
Yes
>> Repair the internal transmission and inspect the Transmission Oil Pump per the Service Information and
replace if necessary. If no problem is found, replace the Transmission Solenoid/TRS Assembly, possible
cause is a stuck Pressure Control Solenoid.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Replace the Line Pressure Sensor per the Service information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
6.
(T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333.
Disconnect the Powertrain Control Module C4 harness connector.
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 (T140) Pressure Control Solenoid Con-
trol circuit from the appropriate terminal of Miller tool #8815 to the
Solenoid/TRS harness connector.
Is the resistance above 5.0 ohms?
Yes
>> Repair the (T140) Pressure Control Solenoid Control cir-
cuit for an open.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION
TEST - VER 1.
No
>> Go To 7
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AUTOMATIC TRANSMISSION - 545RFE - ELECTRICAL DIAGNOSTICS
DR/DH
P0869-LINE PRESSURE HIGH (CONTINUED)
7.
(T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (T140) Pressure
Control Solenoid Control circuit.
Is the resistance below 5.0 ohms?
Yes
>> Repair the (T140) Pressure Control Solenoid Control cir-
cuit for a short to ground.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION
TEST - VER 1.
No
>> Go To 8
8.
(F856) 5-VOLT SUPPLY CIRCUIT OPEN
Measure the resistance of the (F856) 5-volt Supply circuit between the
Line Pressure Sensor harness connector to the appropriate terminal of
Miller tool #8815.
Is the resistance above 5.0 ohms?
Yes
>> Repair the (F856) 5-volt Supply circuit for an open.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION
TEST - VER 1.
No
>> Go To 9
DR/DH
AUTOMATIC TRANSMISSION - 545RFE - ELECTRICAL DIAGNOSTICS
21 - 427
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