2007 Grand Cherokee WK Factory Service Manual 21 - TRANSMISSION AND TRANSFER CASE

STANDARD PROCEDURE

NAG1 PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE

For a complete wiring diagram Refer to Section 8W

Perform the following pre-diagnostic troubleshooting procedures prior to performing any diagnostic test.

NOTE: Low fluid level can be the cause of many transmission problems. Visually inspect the transmission and cooler lines for leakage and repair as necessary and adjust the fluid level per the Service Information. If no visual leaks are observed and the vehicle has obtained over 1610 km (1000 miles) from either new or transmission service, a fluid level check is unnecessary.

Always perform diagnostics with a fully charged battery to avoid false symptoms.


1. With the scan tool, read the engine DTCs. Check and repair all engine DTCs prior to performing transmission symptom diagnostic procedures.
2. With the scan tool, read and record all Transmission DTCs.

NOTE: If the TCM detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set and is located in scan tool under Environmental Data. Before erasing any stored DTCs, it is recommended to record any available data to assist in duplicating the conditions in which the DTC originally set.


3. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Clean and repair as necessary.
4. Most DTCs set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run.
5. Verify flash level of transmission controller. Some problems are corrected by software upgrades to the transmission controller. Verify that no variant DTCs are present. If variant DTCs are present, perform their respective test first.
6. If the TCM (EGS) is flashed, perform a EGS initialization with the scan tool to relearn variant coding.
7. Check for any Service Information Tune-ups or Service Bulletins that may apply.


Did any of the above procedures repair the vehicle?

Yes


No

NAG1 TRANSMISSION VERIFICATION TEST

To validate that the repair(s) fixed the vehicle, perform the following steps.


1. Reconnect any disconnected components.
2. Connect the scan tool to the Data Link Connector.
3. With the scan tool, erase ABS DTCs.
4. With the scan tool, erase PCM DTCs.
5. With the scan tool, erase TCM DTCs.

CAUTION: Apply the parking brake.

NOTE: The Transmission Temperature can only be read while in Reverse or Drive.


6. With the scan tool, display the Transmission temperature. Start and run the engine until the Transmission temperature is above 43° C (110° F).
7. If internal transmission components were repaired or replaced check the Transmission fluid and adjust if necessary. Refer to the Service Information for the proper Fluid Fill procedure. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1/FILTER - STANDARD PROCEDURE)
8. If the TCM (EGS) is flashed or replaced, with the scan tool, perform a EGS initialization to relearn variant coding.
9. If internal transmission repairs are performed or replacement of the Transmission Control Module, perform a TCM ADAPTATION procedure. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - STANDARD PROCEDURE)
10. After performing the above procedures, perform the Road Test Procedure.

ROAD TEST PROCEDURE


1. Road test the vehicle. Make fifteen to twenty 1-2, 2-3, 3-4, and 4-5 upshifts.
2. Perform these shifts from a standing start to 72 Km/h (45 mph) with a constant throttle opening of 20 to 25 degrees.
3. With speeds below 40 Km/h (25 mph), make five to eight wide open throttle kickdowns to 1st gear. Allow at least 5 seconds each in 2nd and 3rd gear between each kickdown.
4. With the scan tool, read DTCs.


Did any DTCs set?

Yes
  • Refer to the identified category and perform the appropriate symptom(s).


No
  • Testing is complete.