Jeep Liberty KJ. Manual — part 1046
8.
CHECK THE (T50) L/R PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO VOLTAGE
Remove the Transmission Control Relay.
Connect a jumper wire between the (Internal) Fused B(+) circuit and
(T16) Transmission Control Relay Output circuit in the Transmission
Control Relay connector.
Ignition on, engine not running.
Measure the voltage of the (T50) L/R Pressure Switch Sense circuit.
Is the voltage above 0.5 volts?
Yes
>> Repair the (T50) L/R Pressure Switch Sense circuit for a
short to voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
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. Check for Service Information Tune-ups or
Service Bulletins for any possible causes that may apply. If
no problems are found, replace the PCM per the Service
Information. With the scan tool, perform QUICK LEARN.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
9.
INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Test Drive the vehicle and verify if the transmission is launching in 2nd gear and/or there is no TCC engagement.
With the scan tool, check the EVENT DATA to help identify the conditions in which the DTC was set.
Check for any Service Information Tune-ups or Service Bulletins for possible causes that may apply.
Are there 2nd gear launches and/or no TCC engagement?
Yes
>> Disassemble and inspect the Valve Body per the Service Information Inspect the Solenoid Switch Valve
for sticking in its bore and repair or replace as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No
>> Test Complete.
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AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS
KJ
P1790-FAULT IMMEDIATELY AFTER SHIFT
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
After a Gear Ratio Error code is stored.
•
Set Condition:
After a Gear Ratio Error DTC has already been set. The DTC is set if the fault happened within 1.3 seconds
of a shift. The DTC set time will vary from 1.214 seconds to 15 seconds.
Possible Causes
FAULT AFTER SHIFT
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
This DTC is not stored alone. It is stored if a Gear Ratio DTC is detected immediately after shift. The existence of
DTC P1790 indicates a mechanical or hydraulic (not electrical) related problems. It should be noted, however, that
all mechanical problems don’t necessarily result in DTC P1790. When this DTC exists, diagnosing the system
should be based on the associated DTC and only mechanical causes should be considered.
Diagnostic Test
1.
FAULT AFTER SHIFT
This DTC is set along with a Gear Ratio DTC. Perform the appropriate test for the Gear Ratio DTC stored.
NOTE: Check Pending DTCs or 1 trip failures if there are no Active or Stored Gear Ratio DTCs.
If there are no possible causes remaining, view repair.
Repair
Refer to the Transmission category and perform the appropriate symptom.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
KJ
AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS
21 - 229
P1794-SPEED SENSOR GROUND ERROR
For a complete wiring diagram Refer to Section 8W.
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AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS
KJ
•
When Monitored:
Every 7ms after a controller reset with transmission in neutral.
•
Set Condition:
After a PCM reset in neutral and Input and Output sensor ratio equals 2.50 to 1.0 ± 50.0 RPM.
Possible Causes
SPEED SENSOR GROUND CIRCUIT OPEN
POWERTRAIN CONTROL MODULE
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
The input and output speed sensors use a common ground circuit. The loss of this common ground results in the
input signal being sensed for both. After a reset in neutral, and after observing a specific ratio, the Speed Check
Fault Counter will increment. Because the speed sensors and the thermistor share the same ground circuit, this
DTC may indicate a loss of the common speed sensor ground. In some cases this fault will cause a Gear Ratio
Error DTC to be set.
Diagnostic Test
1.
PCM AND WIRING
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.
Install the Transmission Simulator, Miller tool #8333 and the Electronic Transmission Adapter kit 8333-1A.
Ignition on, engine not running.
With the Transmission Simulator, set the
9
Input/Output Speed
9
switch to
9
ON
9
and the rotary switch to the
9
3000/
1250
9
position.
With the scan tool, monitor the Input and Output Speed Sensor readings.
Does the Input Speed read 3000 RPM and the Output Speed read 1250 RPM, ± 50 RPM?
Yes
>> Go To 2
No
>> Go To 4
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AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS
21 - 231
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