Troubleshooting the automatic transmission is simplified by using the proven method of diagnosis. One of the most important things to remember is that there is a definite procedure to follow. Do not take short cuts or assume that critical checks or adjustments have already been made.

The following procedures are recommended for checking and/or verifying that the various components are adjusted and operating properly. Use Rotunda Automatic Transmission Tester 014-00737 or equivalent. Follow the manufacturer's instructions.

Shift Test—In Shop

 CAUTION: Never exceed 97 km/h (60 mph) speedometer speed.

A shift test can be performed in the shop to check for 1-2, 2-3 and 3-4 upshifts.

Raise the vehicle with an axle or frame hoist, so that the rear wheels are clear of the floor. Refer to Section 00-02.

 CAUTION: Gradually apply brakes to stop rear wheels.

NOTE: After each test, move the selector lever to NEUTRAL and run the engine at 1000 rpm to cool the transmission.

To determine if automatic upshifts occur, place the transmission selector lever in OVERDRIVE and make a minimum throttle 1-2, 2-3, and 3-4 upshift. When the shift occurs, you will see the speedometer needle make a momentary surge and feel the driveline bump. If the shift points are within specification, the 1-2, 2-3, and 3-4 shift valves and governor are OK.

If the shift points are not within specification, perform a governor check to isolate the concerns.

Shift speed specifications can be found in the Special Specifications booklet.

Some tips on diagnosing concerns with specific components are:

Intermediate Clutch or Intermediate One-Way Clutch: Transmission shift 1-3 or slips in second gear.

Reverse Clutch: Slip or no engagement in R. (Also can be caused by the low-reverse band or servo).

Forward Clutch or Planetary (Low) One-Way Clutch: No engagement in forward ranges, or slip in forward.

Overdrive Band or Servo: No fourth gear, slip in fourth gear, or no engine braking in second gear in range 1.

Direct Clutch: Slip in third or fourth, or no upshift beyond second.

Low-Reverse Band or Servo: No reverse or slip in reverse. Possibly no engine braking in manual low first gear, which would isolate the concern to the band rather than reverse clutch.

Governor: Erratic shifts could be caused by a sticking governor valve.

Accumulators: Leaking seals on the accumulator pistons can cause their respective clutches to slip. If the 2-3 accumulator seals leak, the symptoms could resemble a direct clutch or forward clutch concern.

TV Pressure Low: If the shifts seem soft or mushy, do not make any heavy throttle tests. Check and adjust the TV linkage before making a complete road test. Do not operate vehicle if TV cable is broken or disconnected at throttle body. Damage to friction elements will result since TV pressure is zero.