Preliminary

PRELIMINARY

Two basic procedures are required to help diagnose the transmission. One procedure is for vehicles that are drivable and an alternate procedure for disabled vehicles the will not back up or move forward.

VEHICLE IS DRIVABLE

1. Check for transmission fault codes using the appropriate scan tool.
2. Adjust the gearshift cable if complaint was based on delayed, erratic, or harsh shifts.
3. Road test and note how the transmission upshifts, downshifts, and engages.
4. Check fluid level and condition.

VEHICLE IS DISABLED

1. Check for a broken or disconnected gearshift cable.
2. Check for cracked, leaking cooler lines, or loose or missing pressure-port plugs.
3. Check fluid level and condition.
4. Check shifter linkage: Is the cable connected to the lever at the transmission and does the lever move with gear change on the console shifter? If no movement, repair shift cable and or shifter.
5. With shifter in PARK, attempt to rotate the drive shaft(s) to make sure the transmission output shaft coupler/flange is secure.
6. Check the transfer case operation (if equipped).
7. Raise and support the vehicle on safety stands. With the transmission in PARK, start the engine and allow to idle for several minutes.Shift the transmission into gear and note the following:
a. If the propeller shaft turns but wheels do not, problem is with the differential or axle shafts.
b. If the propeller shaft does not turn and the transmission is noisy, stop the engine. Remove the oil pan and check for debris. If the pan is clear, remove the transmission and check for damaged driveplate, converter, oil pump, or input shaft.
c. If the propeller shaft does not turn and the transmission is not noisy, perform the hydraulic-pressure test to determine if problem is hydraulic or mechanical.
8. Air pressure test the B1, K3, and B2 clutch circuits. Air Checking Transmission Clutch Operation
9. Check the Transmission Control Module (TCM) wiring, valve body, and solenoids. (Utilize fault codes to diagnose if available.).
10. Remove the oil pan and check filter presence and condition (not plugged and seated).
11. If debris is found in the pan, tear down the transmission and inspect all hard parts ( front annulus gear,gear to retainer and, input shaft, etc.) and clutches. If the hard parts do not show signs of damage, replace the torque converter and filter.
12. Remove the valve body, disassemble, and inspect the line pressure regulating valve for being stuck, clean and remove debris.
13. Check the pump rotor for failed inner lugs that are driven by the damper hub.