Symptom:
TRANSMISSION SLIPPING
When Monitored and Set Condition:
TRANSMISSION SLIPPING
When Monitored: Engine rpm greater than 450 rpm, output speed greater than 180 rpm,
no N2 - N3 input speed sensor errors present, no gear selector lever errors present, no ABS
system errors, no transfer case errors present, and all wheel speeds between 70 - 380 rpm
with no wheel slip detected. Set Condition: Calculated ratio not within allowable range for
the engaged gear. No shifting operation.
Set Condition: The TCM constantly calculates the transmission ratio based on the N2 -
N3 input speed signals and the calculated output shaft speed (CAN message from the
ABS). The TCM will detect if the transmission is slipping or an invalid gear ratio is present
POSSIBLE CAUSES
OTHER DTCS PRESENT
AXLE - MECHANICAL - GEAR RATIO
INTERNAL TRANSMISSION
TCM - TRANSMISSION SLIPPING
TEST ACTION APPLICABILITY
1NOTE: 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.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIIIt, read the engine DTCs. Check and repair all engine DTCs prior to
performing transmission symptom diagnostics.
With the DRBIIIt, read and record all Transmission DTCs.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal
connections can set DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Most DTCs 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 any Technical Service Bulletins that may apply.
Perform this procedure prior to Symptom diagnosis.All
Continue
Go To 2
125
TRANSMISSION - NAG1
Verification Tests
NAG1 TRANSMISSION VERIFICATION TEST - VER 1 APPLICABILITY
1. Reconnect any disconnected components.
2. Connect the DRBIIItto the Data Link Connector.
3. With the DRBIIIt, erase ABS DTCs.
4. With the DRBIIIt, erase ECM DTCs.
5. With the DRBIIIt, erase Transmission DTCs.
6. With the DRBIIIt, display Transmission Temperature. Start and run the engine until the
Transmission Temperature is HOT, above 43É C (110É F).
7. Check the Transmission fluid and adjust if necessary. Refer to the Service Information for the
proper Fluid Fill procedure.
8. NOTE: If internal repairs were performed and the shift quality is still poor, it may
be necessary to check the internal repair. Also check for any TSBs and/or Controller
Flash updates that may apply.
9. ROAD TEST PROCEDURE
10. Road test the vehicle. Make fifteen to twenty 1-2, 2-3, 3-4 and 4-5 upshifts.
11. Perform these shifts from a standing start to 72 km/h (45 MPH) with a constant throttle
opening of 20 to 25 degrees.
12. 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.
13. With the DRBIIIt, read Transmission DTCs.
Were there any Diagnostic Trouble Codes set?All
Ye s!Repair is not complete, refer to appropriate symptom.
No!Repair is complete.
127
VERIFICATION TESTS
