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DIAGNOSIS AND TESTING AUTOMATIC TRANSMISSION CAUTION: Before attempting any repair on a NAG1 Transmission malfunctions may be caused by these general conditions: • Poor engine performance. by checking the easily accessible variables: fluid level PRELIMINARY Two basic procedures are required. One procedure for vehicles that are drivable and an alternate proce- VEHICLE IS DRIVABLE (1) Check for transmission fault codes using the appropriate scan tool. (2) Check fluid level and condition. on delayed, erratic, or harsh shifts. (4) Road test and note how transmission upshifts, downshifts, and engages. VEHICLE IS DISABLED (1) Check fluid level and condition. (2) Check for broken or disconnected gearshift cable. (3) Check for cracked, leaking cooler lines, or loose or missing pressure-port plugs. (4) Raise and support vehicle on safety stands, start engine, shift transmission into gear, and note (a) If propeller shaft turns but wheels do not, problem is with differential or axle shafts. (b) If propeller shaft does not turn and transmis- sion is noisy, stop engine. Remove oil pan, and (c) If propeller shaft does not turn and transmis- sion is not noisy, perform hydraulic-pressure test to ROAD TESTING Before road testing, be sure the fluid level and con- trol cable adjustments have been checked and adjusted if necessary. Verify that all diagnostic trou- Observe engine performance during the road test. A poorly tuned engine will not allow accurate analy- Operate the transmission in all gear ranges. Check for shift variations and engine flare which indicates Slippage indicated by engine flare, usually means clutch, overrunning clutch, or line pressure problems. A slipping clutch can often be determined by com- paring which internal units are applied in the vari- CLUTCH APPLICATION GEAR RATIO B1 B2 B3 K1 K2 K3 F1 F2 1 3.59 X* X X* X X 2 2.19 X X X* X 3 1.41 X X X 4 1.00 X X X 5 0.83 X X X X* N N/A X X R 3.16 X* X X X R - Limp In 1.93 X X X * = The shift components required during coast. VA AUTOMATIC TRANSMISSION NAG1 - SERVICE INFORMATION 21 - 39 |