Jeep Grand Cherokee WK. Manual — part 1334
P0846-2C PRESSURE SWITCH RATIONALITY (CONTINUED)
15.
#5 AND/OR #7 CHECK BALL CUT OR DAMAGED
Turn the Ignition off to the lock position.
Remove the Valve Body Assembly per the Service Information.
Inspect the #5 and #7 check balls for any cuts or damage.
Inspect the 2C accumulator piston and seals and also the 2C tower seal on top of the valve body. Refer to the
Service Information.
Where there any problems found?
Yes
>> Repair as necessary. Check for excessive clutch debris in the transmission oil pan. If excessive clutch
debris is present, repair 2C clutch as necessary. Refer to the Service Information for proper repair pro-
cedures.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Go To 16
16.
EXCESSIVE FLUID LEAKAGE WITH 2C CLUTCH CIRCUIT
Air check the 2C Clutch hydraulic circuit. Refer to the Service Information.
NOTE: This hydraulic clutch circuit contains a small bleed orifice. Small leakage is considered normal.
Was there excessive air leakage in the 2C Clutch hydraulic circuit?
Yes
>> Repair as necessary. Refer to the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0868-LINE PRESSURE LOW
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0868-LINE PRESSURE LOW (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 and compares it to Desired Line Pressure. If the Actual
Line Pressure is more than 10 PSI below Desired Line Pressure, this DTC will set.
Possible Causes
CHECK FOR RELATED DTC’S
LOW FLUID LEVEL
(F856) 5-VOLT SUPPLY CIRCUIT OPEN
POOR LINE PRESSURE SENSOR CONNECTION
(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND
(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO VOLTAGE
(T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT
INTERNAL TRANSMISSION
LINE PRESSURE SENSOR
CRACKED, PLUGGED, OR MISINSTALLED PRIMARY OIL FILTER
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 lower than the target while driving, the line pressure low DTC P0868 will set.
Diagnostic Test
1.
CHECK FOR RELATED DTC’S
With the scan tool, check for other transmission DTC’s
Is the DTC P0932 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
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AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS
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P0868-LINE PRESSURE LOW (CONTINUED)
2.
CONDITION P0868 PRESENT
With the scan tool, check the STARTS SINCE SET counter for P0868.
NOTE: This counter only applies to the last DTC set.
Is the START SINCE SET COUNTER 2 or less?
Yes
>> Go To 3
No
>> Go To 11
3.
CHECK LINE PRESSURE SENSOR CONNECTION
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure, firmly push the Line Pressure Sensor harness connector towards the
Transmission.
Did the Line Pressure change to about 207 kPa or 30 PSI when the 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 steps.
Using the Transmission Simulator, set the rotary knob 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 7
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