Jeep Liberty KJ. Manual - part 1017

P0736-GEAR RATIO ERROR IN REVERSE

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
The Transmission gear ratio is monitored continuously while the transmission is in gear.

•

Set Condition:
If the ratio of the Input RPM to the Output RPM does not match the current gear ratio when compared to the
known gear ratio.

Possible Causes

RELATED TRANSMISSION DTCS PRESENT

INTERMITTENT GEAR RATIO ERRORS

INTERNAL TRANSMISSION

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

Theory of Operation

The transmission system uses two speed sensors, one to measure input RPM and one to measure output RPM.
These inputs are essential for proper transmission operation. Therefore, the integrity of this data is verified through
data checks. When in gear, if the gear ratio does not compare to a known gear ratio, the corresponding gear ratio
error trouble code is set. The transmission will go into Limp-in mode after four gear ratio error events occur in a
given driving cycle.

Diagnostic Test

DETERMINING IF RELATED TRANSMISSION DTCS ARE PRESENT

With the scan tool, read Transmission DTCs.

If any of these DTCs are present, perform their respective tests first.

Are there any Loss of Prime, Line Pressure Sensor and/or Speed Sensor DTCs present?

Yes

>> Refer to appropriate diagnostic procedure in the Transmission category. If any of these DTCs are

present, they will cause a gear ratio error. Perform the test for Loss of Prime first if it is present.

>> Go To 2

CHECK TO SEE IF P0731 IS CURRENT

With the scan tool, perform the Reverse gear clutch test. Follow the instructions on the scan tool.

Increase the throttle angle or TPS Degree to 30° for no more than a few seconds.

CAUTION: Do not overheat the transmission.

Did the Clutch Test pass, Input Speed remain at zero?

Yes

>> Go To 3

>> Repair internal Transmission per the Service Information. Check all of the components related to the

Reverse and LR clutches. Inspect the Oil Pump and repair or replace as necessary.

Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

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AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS

CHECK FOR INTERMITTENT OPERATION

The conditions to set this DTC are not current at this time.

Check the gearshift linkage adjustment.

Gear ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits. If the vehicle passes the
Clutch Test and still sets Gear Ratio DTC, check the Speed Sensors for proper operation.

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 and the Electronic Transmission Adapter kit.

Check the wiring and connectors related to the Speed Sensors for a good connection, then perform a wiggle test
using the Transmission Simulator.

This DTC can also be set under extreme temperature conditions, this is usually caused by an internal problem.
Verify if the problem is only experienced under extreme hot or cold conditions.

With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.

Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply.

Were there any problems found?

Yes

>> Repair as necessary.

Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

>> Test Complete.

AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS

21 - 113

P0740-TCC OUT OF RANGE

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
The Torque Converter Clutch (TCC) is in FEMCC or PEMCC, Transmission temperature is hot, Engine tem-
perature is greater than 38° C or 100° F, Transmission Input Speed greater than engine speed, TPS less than
30°, and brake not applied.

•

Set Condition:
The TCC is modulated by controlling the duty cycle of the L/R Solenoid until the difference between the Engine
RPM and the Transmission Input Speed RPM or duty cycle is within a desired range. The DTC is set after the
period of 10 seconds and 3 occurrences of either: FEMCC - with slip greater than 100 RPM or PEMCC - duty
cycle greater than 85%.

Possible Causes

RELATED L/R SOLENOID OR PRESSURE SWITCH DTCS PRESENT

INTERNAL TRANSMISSION

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

Theory of Operation

When in 2nd, 3rd, or 4th gear, the torque converter clutch (TCC) can be locked or partially locked when certain
conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR/TCC solenoid
until the torque converter slip difference (difference between engine and turbine speed) is within 60 RPM. Then the
LR/TCC solenoid is fully energized (FEMCC / 100% duty cycle). Torque converter slip is monitored in FEMCC to
ensure adequate clutch capacity. The transmission will attempt normal EMCC operation (not in Limp-in) even after
the MIL is illuminated. MIL will illuminate after 5 minutes of accumulated slip in FEMCC.

Diagnostic Test

CHECK IF RELATED DTCS ARE PRESENT

With the scan tool, read Transmission DTCs

Are the DTCs P0750 and/or P0841 present also?

Yes

>> Refer to the Transmission category and perform the appropriate symptom.

>> Go To 2

CHECK IF THE DTC IS CURRENT

Ignition on, engine not running.

With the scan tool, record and erase DTCs.

Drive the vehicle until it is fully warmed up to at least 43° C (110° F).

Perform the following step 3 times.

Drive the vehicle at 50 mph and allow 4th gear to engage for at least 10 seconds. Close the throttle, then tip back
in until the throttle angle is between 25 and 29 degrees. Note that if you go over 30 degrees, you must back off of
the throttle and retry.

Did the TCC engage during any of the attempts?

Yes

>> Go To 3

>> Perform the Hydraulic Pressure test per the Service Information and repair the internal transmission

components and Torque convertor as necessary.

Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

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AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS

INTERMITTENT WIRING AND CONNECTORS

The conditions necessary to set the DTC are not present at this time.

Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.

Wiggle the wiring and connectors while checking for shorted and open circuits.

This DTC can also be set under extreme temperature conditions. This is usually caused by an internal problem.
Verify if the problem is only experienced under extreme hot or cold conditions.

With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.

Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply.

Were there any problems found?

Yes

>> Repair as necessary.

Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

>> Test Complete.

AUTOMATIC TRANSMISSION 42RLE - ELECTRICAL DIAGNOSTICS

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