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(a) PARK position—Apply forward force on cen- ter of lever and remove pressure. Engine starts (b) PARK position—Apply rearward force on cen- ter of lever and remove pressure. Engine starts (c) NEUTRAL position—Normal position. Engine starts must be possible. (d) NEUTRAL position—Engine running and brakes applied, apply forward force on center of ROAD TESTING Before road testing, be sure the fluid level and con- trol cable adjustments have been checked and adjusted if necessary. Verify that diagnostic trouble 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, band or overrunning clutch problems. If the A slipping clutch or band can often be determined by comparing which internal units are applied in the ANALYZING ROAD TEST Refer to the Clutch and Band Application chart and note which elements are in use in the various Note that the rear clutch is applied in all forward ranges (D, 2, 1). The transmission overrunning clutch Note that the overdrive clutch is applied only in fourth gear and the overdrive direct clutch and over- For example: If slippage occurs in first gear in D and 2 range but not in 1 range, the transmission Applying the same method of analysis, note that the front and rear clutches are applied simulta- transmission slips in third gear, either the front If the transmission slips in fourth gear but not in third gear, the overdrive clutch is slipping. By select- If slippage occurs during the 3-4 shift or only in fourth gear, the overdrive clutch is slipping. Simi- If the transmission will not shift to fourth gear, the control switch, overdrive solenoid or related wiring This process of elimination can be used to identify a slipping unit and check operation. Proper use of Although road test analysis will help determine the slipping unit, the actual cause of a malfunction usu- Unless a malfunction is obvious, such as no drive in D range first gear, do not disassemble the trans- HYDRAULIC PRESSURE TEST Hydraulic test pressures range from a low of one psi (6.895 kPa) governor pressure, to 300 psi (2068 An accurate tachometer and pressure test gauges are required. Test Gauge C-3292 has a 100 psi range Pressure Test Port Locations Test ports are located at both sides of the transmis- sion case (Fig. 66). Line pressure is checked at the accumulator port on the right side of the case. The front servo pressure The rear servo and governor pressure ports are at the right rear of the transmission case. The overdrive 21 - 46 42/44RE AUTOMATIC TRANSMISSION DN DIAGNOSIS AND TESTING (Continued) |