Automatic Transmission/Transaxle (A2)

C. In-Vehicle Transmission-Transaxle Repair Answers and Explanations

1. The correct answer is b. Technician B is correct because the vacuum modulator adjustment shown changes the shift points at low speeds under minimum or part-throttle conditions where engine vacuum has the most influence based on engine load. Technician A is not correct because the engine vacuum is close to or equal to zero at wide-open throttle operation and the vacuum modulator has no affect on the shifting points under these conditions. Answers c and d are not correct because Technician B only is correct.

2. The correct answer is c. Both technicians are correct. Technician A is correct because if the TV cable breaks, some transmissions have a fail-safe check ball in the valve body that increases the throttle pressure in the event of TV cable failure. Technician B is correct because a broken throttle valve (TV) cable would prevent the transmission from delaying the shift due to throttle position and would shift as if the throttle were not being depressed. This can cause the shifts to occur too early. Answers a, b, and d are not correct because both technicians are correct.

3. The correct answer is a. Technician A is correct because trapped debris in the cooler could be drawn into the new automatic transmission/transaxle where it could cause excessive wear or sticking of valves and other faults if the cooler and cooler lines are not thoroughly cleaned. Technician B is not correct because some remaining water-based solvent may remain trapped in the cooler where it can cause severe damage to the friction discs if allowed to circulate through the automatic transmission/transaxle. Most friction material uses water-soluble glue to hold the friction material to the steel backing plate, and any water in the system can cause the friction material to separate from the backing and travel through the system causing valves to stick and causing other faults. Answers c and d are not correct because Technician A only is correct.

4. The correct answer is c. Both technicians are correct. Technician A is correct because most coolers should be able to flow about one gallon per minute or at least 2 quarts (liters) in 30 seconds. If less than 2 quarts of fluid is measured flowing through the cooler, then the cooler or cooler line(s) are restricted or clogged and should be cleaned or replaced. Technician B is correct because the engine and the pump should be operated at about 1000 RPM (fast idle) during the cooler flow test. If the engine speed is too slow, the transmission/transaxle pump may not be able to supply the specified volume of fluid and the results would indicate a restricted cooler. Answers a, b, and d are not correct because both technicians are correct.

5. The correct answer is c. Both technicians are correct. Technician A is correct because the drive shaft slip yoke attaches to the output shaft of the transmission and has to be removed to replace the seal. Technician B is correct because a worn bushing can cause the slip yoke to wear or damage the seal. Failure to replace the bushing in the extension housing can cause premature failure of the replacement seal. Answers a, b, and d are not correct because both technicians are correct.

6. The correct answer is c. Both technicians are correct. Technician A is correct because in many transmission range switches, each gear position has a known resistance through which a voltage signal is sent. If there is corrosion in the connector, the resistance may not match the gear selected by the driver. Technician B is correct because the connector usually controls the operation of the backup (reverse) lights and the corrosion could cause enough of a voltage drop (resistance) to prevent the proper operation of the backup lights. Answers a, b, and d are not correct because both technicians are correct.

7. The correct answer is a. The photo shows the valves that the shift solenoids operate. If any of these valves were to stick or not seat properly, shifting problems can occur. Answers b and c are not correct because the parts shown are not a governor or throttle valve. Answer d is not correct because even though the part is attached to the valve body, the technician is inspecting the solenoid valve rather than the shift valves for wear or damage.

8. The correct answer is c. Both technicians are correct. Technician A is correct because the shifts are occurring too late (22 MPH instead of the specified speed of 12-15 MPH according to the chart). Low engine vacuum or a defective vacuum modulator could be the reason because the vacuum modulator monitors engine load and causes the transmission to delay the shift when the engine is under a load such as when climbing a hill or accelerating rapidly. Technician B is correct because the shift between first and second is delayed and the governor helps determine shift points based on vehicle speed. A fault with the governor itself or the governor circuit could cause the shift points to be later than specified. Answers a, b, and d are not correct because both technicians are correct.

9. The correct answer is a. To check for the location of a pressure leak, the best method is to perform an air pressure test where regulator air pressure (25-30 psi) is applied to the various fluid passages and observe or listen for the proper application of the clutches and bands. Answer b is not correct because the mainline pressure, while it should be checked, cannot be measured in this case because the oil pan has been removed and the engine should not be started. Answer c is not correct because inspecting the valve body will not identify the location of a pressure leak. Answer d is not correct because the pump pressure cannot be measured with the pan removed.

10. The correct answer is c. A worn extension housing bushing can cause excessive movement of the slip yoke to occur leading to leakage between the yoke and the rear seal. Answer a is not correct because even though too high level of automatic transmission fluid (ATF) can cause problems, it is unlikely to be the cause of a leak from the rear seal. Answer b is not correct because endplay occurs in the longitudinal axis of the output shaft and is unlikely to cause the rear seal to leak fluid. Answer d is not correct because a slipping yoke can wear on the inside (splines) and on the outside due to dirt wearing the outer surface, but is unlikely to wear enough to cause a leak.

11. The correct answer is d. Neither technician is correct. Technician A is not correct because the shift solenoids can be safely removed without causing harm without disconnecting the battery as long as the ignition switch is off. A voltage spike could occur, which could cause damage to the vehicle computer (not the valve body) if a solenoid is disconnected with current flowing through the windings of the solenoid. Technician B is not correct because the torque converter clutch solenoid is usually located in the valve body area and the torque converter does not need to be removed to replace the torque converter clutch solenoid. Answer c is not correct because neither technician is correct.

12. The correct answer is a. Technician A is correct because the unit shown is the vehicle speed sensor, also known as the output shaft speed sensor, and is usually located in the extension housing. The signals from this sensor are often used by the vehicle computer for speedometer and cruise control as a shift control and slippage fault detection. Technician B is not correct because the unit shown is a vehicle speed sensor and not a turbine or input speed sensor, which would be installed toward the front or input end of the transmission. Answers c and d are not correct because Technician A only is correct.

13. The correct answer is c. Both technicians are correct. Technician A is correct because a typical band adjustment procedure specifies that the lock nut be loosened and the adjusting screw tightened to a specified torque using a torque wrench. Technician B is correct because the band adjustment procedure usually includes loosening the adjustment screw a specified number of times after it has been tightened to a specified torque. Answers a, b, and d are not correct because both technicians are correct.

14. The correct answer is b. Technician B is correct because the modulator spring is weak as shown. The gauge centerline mark should remain in the center as the two modulators, one known good and the other in question, are being tested if the internal springs are the same. The illustration shows that the centerline mark is toward the modulator in question indicating that the unit has a weak spring and bellows and the modulator is bad. Technician A is not correct because the modulator is bad as indicated by the centerline on the gauge. Answers c and d are not correct because Technician B only is correct.

15. The correct answer is a. A worn band is the most likely cause for the band adjustment to be incorrect. Answer b is not correct because the drum is steel and is less likely to wear than the friction surface of the band. Answer c is not correct even though low fluid level could be the root cause of the worn band. The most likely cause for the adjustment being needed is due to wear on the band. Answer d is not correct because, while a defective pressure regulator could cause the band to wear prematurely, it is the wear on the band itself that makes the adjustment necessary.

16. The correct answer is a. Technician A is correct because dark brown and rancid smelling fluid indicates that the fluid has been overheated. A thorough inspection and testing of the cooler and cooler lines should be performed and any faults corrected before refitting the automatic transmission with fresh fluid. Technician B is not correct because even though using the wrong fluid can cause shifting problems, it is unlikely to cause the extreme temperature needed to oxidize the fluid enough to cause it to turn dark brown and have a rancid smell. Answers c and d are not correct because Technician A only is correct.

17. The correct answer is d. Answer d is correct because filters should be replaced rather than cleaned. Answers a, b, and c are not correct because all are correct service procedures.