Valvebody and pressures - automatic transmission/transaxle
All of the following statements are true excepte
A. Throttle valves are located inside the transmission valvebody B. As the throttle opening increases, throttle valve pressure decreases C. Increased throttle pressure delays the upshift D. Decreased throttle pressure allows up shifts Answer: As the throttle opening increases, throttle valve pressure decreases
Delayed shift is caused by
An improperly adjusted from start TRUE
Modulated pressure is
Applying pressure
Tech a says that line pressure is an automatic transmission varies with engine rpm. Tech b says that modulator pressure changes with engine vacuum. Who is correct?
Both Techs are correct
Tech a says that sometimes MAF sensors can be cleaned when they have a buildup of dirt and contamination. Tech B says that some manufacturers specifically say not to clean their MAF sensors. Who is correct
Both techs A and B are correct
Hydraulic controlled servos are
Brake bands
The transmission fluid temp sensor can read everything except
Burnt transmission fluid
Epc stands for
Electronic pressure control
If the atf is pink and milky is can be from the vehicle over heating. True or false
FALSE - engine did not over heat
Seal is leaking and the bushing
False
Today's electronic transmission
False
Trans loses pressure with a stuck servo
False
A potentiometer is used for what purpose
It is used for load calculations for automatic transimssions
If an automatic transmission only had a governor and no throttle valve or vacuum modulator what is the shift most likely to be like?
It would shift at the same point no matter what engine load it is
The vacuum modulator converts the engine vacuum signal into
Line pressure
Harsh shifting
Line pressure is too high while cruising
Which of the of the following is a pressure transducer
Line pressure sensor
Slips while turning corners
Low fluid level
The device that varies incoming line pressure using centrifugal force is known as
Modulator pressure
Pressures
Normal 60-120 Wot 90-150 Reverses los 150-300
Tcc is not used for
Not used for shift control
Lacks power from stop
One way clutch is bad or the transmission is slipping
Which of the following sends either simple on or off signals or pulse width modulated signals to the actuator depending on the actuator being controlled
Output driver
Some torque converter clutch (TCC) solenoids are a
Pulse width modulated solenoid
Which gear needs higher line, pressure and the modulator/throttle valve pressure are not used?
Reverse
Internal gear with teeth
Ring gear
The check balls are seperated by a
Separator plate
Map has no effect on what
Shift quality
An electro-mechanical device is used to control oil flow to bands and clutches in an automatic transmission is thes
Shift solenoid
Which of the following has multiple lands designed to block or allow line pressure to pass to a band or clutch in order to apply the gear?
Shift valve
Shift valves are called
Spool valves
Lean mixture
Steal Hesitation Stumble Hard start Misfire
Tcc not working
TFT sensor ect sensor TRUE
Epc regulates line pressure according to engine speed and torque. True or false
TRUE
Epc solenoid is a variable force solenoid
TRUE
Internal transmission cooler is cooled by the engine. True or false?
TRUE
TFT (trans fluid temp sensor) is also a thermistor. True or false
TRUE
Tech A says that a vacuum modulator converts manifold vacuum into an engine load signal. Tech B says modulator pressure changes with the manual valve is moved by governor pressure to force a shift
Tech A
Tech a says that delayed shifts could be caused by a malfunctioning throttle position sensor. Tech b says that TPS data can be used to determine clutch slippage. Who is correct?
Tech A
Harsh 3-4 shift
Tech A says the accumulator piston may be stuck
Tech A says the engine coolant temp (ECT) sensor is an electro-magnetic type of sensor. Tech b says the PCM or TCM uses the ect to vary shift timing and pressure based on engine performance
Tech B
Trs (transmission range sensor)
Tested with an ohmeter
When the governor pressure becomes great enough to overcome the spring pressure and the modulator/throttle valve pressure in the 2-3 shift valve pressure in the 2-3 shift valve, line pressure is allowed to flow to:
The 3rd gear clutch or band
Which of the following works just like a transmission oil temp (TOT) sensor
The Engine coolant temp sensor (ECT)
Shift solenoids can be commanded by
The pcm
Downshift occurs when
The throttle is commanded on
General Motors Powertrain and transmission control modules can calculate a parameter called tap. What can the tap be used for?
To determine how worn the clutch or band is and to adjust shift timing and pressures to match worn clutches and bands
Testing points are located on the
Transmission case
A scan tool and ohmmeter can diagnose a TFT
True
Depth of torque converter should be measure before removal
True
Pressure test an automatic transmission if an internal
True
The tcm info from other ect is tcc control
True
Trans loses pressure as it shifts from 1st to 2nd
True
Bad u joint
True - extension housng
Which of the following is another name for the input shaft speed sensor
Turbine speed sensor
Shift valves are also
VALVES AND SWITCHES
Harsh shifting transmission could be caused by
When the line pressure is too high during normal cruising speeds