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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Torque Converter Clutch (TCC) unlocked for 10 sec., ECM commands converter lock-up and did not record engine speed drop.
Possible symptoms
•Engine Light ON (or Service Engine Soon Warning Light)
•Transmission shift shock
•Vehicle may not shift into the highest gear
No issues with the transmission or shifting when the code first appeared. TCC was locking up and vehicle going into OD. Took the jeep to a transmission shop for diagnosis. They performed an evaluation (basically a test drive) and found the transmission to be working properly. Cleared the code and recommended I complete a couple drain and fills to improve the condition of the transmission fluid. This after they drained the pan and replaced the filter in October 2016 when I first purchased. PO neglected the transmission and the fluid was very dark when I got it. Completed a series of drain and fills to improve the fluid condition.
Code stayed away for a while then started back again in December 2017. On and off until I again took it back to the transmission shop for a diagnosis a few days ago. Prob should have taken it in sooner but the vehicle is my high school daughter's DD and she said she did not notice any transmission issues. When I drove it prior to taking it in it did not appear that the TCC was going into lock-up. Was also not sure it was shifting into OD.
Transmission shop said the the TCC clutch is not applying (lock-up) and that they are 95% sure it is due to an internal mechanical failure. Not electrical, circuit or solenoid issue. They are basing this on the DTC code of P0740, which they say is a mechanical fault NOT an electric circuit fault. Also said the condition of the transmission fluid supports an internal failure of the TCC since the fluid is somewhat dark and varnished. The fluid is not bad IMO and is much better since the drain and fills. The trans shop did not recommend going through and testing the wiring and resistance of the solenoids as would cost extra and they did not want to recommend since they think it is an internal mechanical issue.
I have read numerous threads with folks also having the same DTC and resolving the issue with replacing the TPS, stop lamp switch, TCC solenoid or other. However, I do not think I read any posts related to issues of the TCC failing, coming apart and destroying the transmission? Has anyone experienced this?
I am not ready to accept that the issue can only be resolved with a full rebuild until I have performed the following:
New stop lamp switch (break switch)
Test resistance of solenoids at TCM harness
TPS was replaced w/ new Mopar several months back
What else would you recommend if this was your Jeep?
Thanks in advance for all help!
When trying to diagnose a problem, I sometime look through the DTC diagnostics from Jeeps service manual. However the standard manual for my 98 doesn't have all of Jeep's DTC diagnostics. There are a bunch of add-ons and other Jeep manuals that aren't included with the standard Jeep service manual.
I have a 2000 / 2001 Service manual that appears to have been revised with additional DTC diagnostic procedures.
I do have some additional 98 Jeep Cherokee paper manuals such as a 122 page AWF Transmission manual. However it doesn't list diagnostic referencing DTC codes and uses many diagrams and logic diagrams to explain how to diagnose problems that have no references to DTCs.
You need to remember Jeep Manuals are designed for Jeep authorized service technicians using Chrysler diagnostic tools & equipment, including Chrylser DRB scanner and related diagnostic equipment.
However you can skip over parts that that mention using the DRB scanner and related test equipment. Sometimes I've used a DMM and or a OBD scanner instead of the DRB diag. equipment to perform certain types of measurements and tests.
Also Jeep diagnostic procedures often refer to other diagnostics procedures. You would need to find these procedure as I'm uncertain which manual(s) from which the referred procedures are listed.
I found if I carefully read through some of Jeep/Chrysler diagnostics provided me with other diagnostic elements which allowed me to narrow down some types of problems. Though Jeep diagnostics is mostly based on DTCs it does include diagnostic procedures when no DTC is found
Diagnostic procedure's from a 2000/2001 service manual.
P0740 (M) Torq Con Clu, No RPM Drop at Lockup
Relationship between engine and vehicle speeds indicated failure of torque convertor clutch lock-up system (TCC/PTU solenoid)
_________________________________________
When Monitored and Set Condition:
P0740-SOLENOID C FUNCTIONAL FAULT
When Monitored: Continuously with Solenoid C (TCC) energized.
Set Condition: When the solenoid is energized and the Engine RPM does not equal the Transmission’s Input Speed RPM or when the solenoid is deenergized and the Engine RPM equals Transmission input RPM.
TPS DTC P0122 PRESENT IN THE TCM
TPS DTC’S PRESENT IN THE PCM
TCM DTC’S P1748 AND/OR P1749 PRESENT
INTERMITTENT WIRING AND/OR CONNECTORS
TRANSMISSION OIL BURNT AND/OR CONTAINS EXCESSIVE DEBRIS
INTERNAL TRANSMISSION
NOTE: Always perform diagnostics with a fully charged battery to avoid
diagnosing false symptoms.
NOTE: Low fluid level can be the cause of many transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the service information.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Verify the brake switch input to the TCM is working correctly.
Perform the shift lever position test and adjust the linkage if necessary.
Test drive vehicle to verify customer complaint.
With the DRBIIIt, read the PCM DTC’s. Check and repair all PCM DTC’s before performing transmission diagnostics.
With the DRBIIIt, read the TCM DTC’s.
Note: Check 1 trip failures and diagnose them as DTC’s (Hard codes)
Most DTC’s set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run.
Note: Verify flash level of transmission controller. Some problems are corrected by software upgrades to the transmission controller.
NOTE: Check for applicable TSB’s related to the problem. Perform this procedure prior to symptom diagnosis.
Go To 2
-- (2) -----------------------
When monitored: Continuously with the Torque Convertor Clutch Solenoid (Solenoid C) energized.
When set: When the solenoid is energized and the Engine RPM does not equal the Transmission’s Input Speed RPM or when the solenoid is deenergized and the Engine RPM equals Transmission input RPM.
This is the When monitored / When set conditions for DTC P0740.
Go To 3
-- (3) ----------------------
With the DRBIIIt, erase DTC’s.
Test drive the vehicle.
Maintain a steady speed of 55 MPH for 30 seconds. Bring the vehicle slowly to a complete stop.
NOTE: Check shift patterns while the vehicle is upshifting and downshifting.
Did Solenoid C (TCC) engage properly during the test drive?
Yes ® Go To 4
No ® Go To 5
-- (4) ----------------------------
Using the when monitored / when set conditions, attempt to reset the DTC. If the DTC can be reset return to the symptom list and perform the appropriate diagnostic test.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
NOTE: Check the Technical Service Bulletins.
Were any problems found?
Yes ® Repair the wiring and/or connectors as necessary.
Perform AW4 TRANS VERIFICATION TEST-VER1.
No ® Test Complete.
-- (5) ---------------------------
With the DRBIIIt, read Transmission DTC’s.
Is P-0122 Throttle Position Sensor DTC present?
Yes ® Refer to the Transmission category and perform the appropriate TCM Throttle Position DTC diagnostic before continuing.
Perform AW4 TRANS VERIFICATION TEST-VER1.
No ® Go To 6
-- (6) ---------------------------
With the DRBIIIt, read the PCM DTC’s.
Is there a TPS DTC present?
Yes ® Refer to the Driveability category and perform all the appropriate PCM Throttle Position DTC’s diagnostic’s before continuing.
Perform AW4 TRANS VERIFICATION TEST-VER1.
No ® Go To 7
-- (8) ----------------------------
Turn ignition off to the lock position.
Remove the transmission oil pan per the service information.
Inspect the pan and fluid for excessive debris or friction material.
Is the oil burnt and/or does the pan contain excessive debris or friction material.
Yes ® Repair internal transmission problem.
Perform AW4 TRANS VERIFICATION TEST-VER1.
No ® Go To 9
- (9) -----------------------------
Turn ignition off to the lock position.
Replace Solenoid C.
With the DRBIIIt, erase DTC’s.
Test drive the vehicle, maintain a steady speed of 55 MPH for at least 30 seconds. Slowly come to a complete stop.
NOTE: Check the shift patterns while the vehicle is upshifting and downshifting.
Is the problem repaired?
Yes ® Test Complete.
No ® Repair internal transmission problem as necessary.
Perform AW4 TRANS VERIFICATION TEST-VER1
______________________________________________
I found the 2000/2001 XJ service manual to be more complete than my 98 Jeep service manual with more diagnostic procedures. Mine is an off-line version, however I found an online version where you can download the manual that's split up into several pdf files.
Here's a link to an online 2001 XJ Service manual. Different sections of the manual are divided into separate pdf files.
02-15-2018, 03:25 PM
P0740 - Need Advice Please!
