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The hydraulic control system design (without electronic assist) provides the transmission with PARK, REVERSE, The TCM also performs certain self-diagnostic functions and provides comprehensive information (sensor data, DIAGNOSIS AND TESTING AUTOMATIC TRANSMISSION CAUTION: Before attempting any repair on a RFE automatic transmission, check for Diagnostic Trouble Transmission malfunctions may be caused by these general conditions: • Poor engine performance • Improper adjustments • Hydraulic malfunctions • Mechanical malfunctions • Electronic malfunctions Diagnosis of these problems should always begin by checking the easily accessible variables: fluid level and con- PRELIMINARY Two basic procedures are required. One procedure for vehicles that are drivable and an alternate procedure for VEHICLE IS DRIVABLE 1. Check for transmission fault codes using scan tool. 2. Check fluid level and condition. 3. Adjust gearshift cable if complaint was based on delayed, erratic, or harsh shifts. 4. Road test and note how transmission upshifts, downshifts, and engages. 5. Perform hydraulic pressure test if shift problems were noted during road test. 6. Perform air-pressure test to check clutch operation. 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 following: a. If propeller shaft turns but wheels do not, problem is with differential or axle shafts. b. If propeller shaft does not turn and transmission is noisy, stop engine. Remove oil pan, and check for debris. If pan is clear, remove transmission and check for damaged driveplate, converter, oil pump, or input shaft. c. If propeller shaft does not turn and transmission is not noisy, perform hydraulic-pressure test to determine if problem is hydraulic or mechanical. ROAD TESTING Before road testing, be sure the fluid level and control cable adjustments have been checked and adjusted if nec- HB AUTOMATIC TRANSMISSION 545RFE - SERVICE INFORMATION 21 - 617 |