Jeep Liberty KJ. Manual - part 1147

P0845-2C HYDRAULIC PRESSURE TEST

For a complete wiring diagram Refer to Section 8W.

21 - 532

AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS - (DIESEL)

•

When Monitored:
In any forward gear with engine speed above 1000 RPM shortly after a shift and every minute thereafter.

•

Set Condition:
After a shift into a forward gear, with engine speed above 1000 RPM, the TCM momentarily turns on element
pressure to the Clutch circuits that don’t have pressure to identify the correct Pressure Switch closes. If the
Pressure Switch does not close 2 times, the DTC sets.

Possible Causes

LINE PRESSURE SENSOR

TRANSMISSION FLUID CONTAMINATION

RELATED TCM POWER INPUT DTCS PRESENT

TRANSMISSION SOLENOID/TRS ASSEMBLY

EXCESSIVE DEBRIS IN OIL PAN

POOR LINE PRESSURE SENSOR CONNECTION

(T147) 2C PRESSURE SWITCH SENSE CIRCUIT OPEN

TRANSMISSION CONTROL RELAY DTCS PRESENT

(T147) 2C PRESSURE SWITCH SENSE CIRCUIT OPEN

(T39) 5-VOLT SUPPLY CIRCUIT OPEN

(T147) 2C PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND

(T39) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND

(T147) 2C PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE

TRANSMISSION SOLENOID/TRS ASSEMBLY

INTERNAL TRANSMISSION

TRANSMISSION CONTROL MODULE

Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Theory of Operation

The Transmission Control System tests the pressure switches when they are off. The test verifies that the switches
are operational (They will close with pressure applied). The Transmission Control System verifies that the switch
closes when the corresponding element is applied. If a switch fails to close, it is re-tested. If it fails the second test,
the DTC will set, the MIL will illuminate and the transmission system will default to the orderly Shutdown routine.

Diagnostic Test

CHECK FOR RELATED DTCS

With the scan tool, check for other transmission DTCs

Are there any Loss of Prime and/or TCM Power Input DTCs present also?

Yes

>> Refer to the Transmission category and perform the appropriate symptom. If the DTC, P0944-LOSS OF

PRIME is present, perform its respective test first. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING)

>> Go To 2

AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS - (DIESEL)

21 - 533

CHECK IF DTC P0755 IS PRESENT

With the scan tool, check Transmission DTCs.

Is the DTC P0755 also present?

Yes

Refer to the Transmission category and perform diagnostics for P0755-2C SOLENOID CIRCUIT. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING)

>> Go To 3

CHECK IF DTCS P0732, P0735 AND/OR P0846 ARE PRESENT

With the scan tool, check for other transmission DTC’s

Are the DTCs P0732, P0735, and/or P0846 present also?

Yes

>> Go To 12

>> Go To 4

CHECK IF DTC P0845 IS CURRENT

With the scan tool, Check the STARTS SINCE SET counter for P0845.

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

Is the STARTS SINCE SET counter 2 or less?

Yes

>> Go To 5

>> Go To 17

CHECK IF THE LINE PRESSURE STAYS THE SAME

Start the engine.

Warm the transmission to 82° C or 180° F.

Firmly apply the brakes.

With the scan tool, monitor the Line Pressure during the following step.

Move the shift lever to each gear position, pausing momentarily in each position and record the line pressure read-
ing. Allow the pressure to stabilize for at least 5 seconds in each range.

Did the line pressure remain at a steady value between 585 and 655 kPa or 85 and 95 psi in each posi-
tion?

Yes

>> Go To 6

>> Go To 10

CHECK THE LINE PRESSURE SENSOR CONNECTION

Ignition on, engine not running.

With the scan tool, monitor the Line Pressure while firmly pushing the Transmission Line Pressure Sensor connector
inwards towards the Transmission.

Did the Line Pressure reading on the scan tool change to about 207 kPa or 30 psi when the connector
was pushed inward?

Yes

>> Disconnect and properly reconnect the Line Pressure Sensor connector. Inspect terminals and repair as

necessary.

Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

>> Go To 7

21 - 534

AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS - (DIESEL)

CHECK THE LINE PRESSURE SENSOR OPERATION

Turn the ignition off to the lock position.

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 can result in personal injury
or death.

NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.
Install the Transmission Simulator, Miller tool #8333.

With the Transmission Simulator select the

OFF

position on the

Input/Output Speed

switch.

Ignition on, engine not running.

With the scan tool, monitor the Line Pressure while turning the Pressure Switch selector to each of the 3 line pres-
sure positions on the Transmission Simulator.

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 scan tool Line Pressure readings match the specified readings on the Transmission Simulator
and remain steady in all three positions?

Yes

>> Replace the Line Pressure Sensor per the Service Information.

Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

>> Go To 8

CHECK THE (T39) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN

Turn the ignition off to the lock position.

Disconnect Transmission Simulator.

Disconnect the TCM harness connector.

Measure the resistance of the (T39) 5-volt Supply circuit from the Line
Pressure Sensor harness connector to the appropriate terminal of the
TCM harness connector.

Is the resistance above 5.0 ohms?

Yes

>> Repair the (T39) 5-volt Supply circuit for an open.

Perform 45RFE/545RFE TRANSMISSION VERIFICATION
TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PRO-
CEDURE)

>> Go To 9

AUTOMATIC TRANSMISSION 545RFE - ELECTRICAL DIAGNOSTICS - (DIESEL)

21 - 535

Content .. 1145 1146 1147 1148 ..