ATASA 5 th Study Guide Be Certain to Read the Summary Chapter 42 Pages 1245 1270 Automatic Transmissions & Transaxle Service 31 Points
1. Prior to beginning any service work on a transmission, it correctly by observing identification numbers, pan shape, and VIN if possible for accurate year of manufacture. Identify Total Verify
2. Diagnosis starts with checking the ATF &, a thorough visual inspection, checking linkage adjustments, retrieving all DTCs, and checking basic engine operation. Color & Smell Level & Condition Brand & Miscibility
3. Both low (under filled) ATF levels as well as high (over filled) ATF levels lead to fluid. (air being drawn into the pump, resulting in low pressure) (foaming can be caused by over filling) Aeration Ovation Creation
4. ATF is in color and has special additives to meet & requirements. Red, Flow & Friction Purple, Flow, Friction Brown, Flow, Friction
5. When contaminated by or coolant, ATF takes on a milky color but also gets a little pink Water 80w90 Coolant
6. ATF brands are tested for their or compatibility with other brands.but HUGE NOTE: There is not one fluid for all automatics: Dexron, Mercon, Synthetic ATF 4 & ATF 5, among others. Reliability Miscibility Mixability
Type F Introduced by Ford in 1967 for their automatics. Also used by Toyota. Type CJ Special fluid for Ford C6 transmissions. Similar to Dexron II. Must not be used in automatics that require Type F. Can be replaced with Mercon or Mercon V. Type H Another limited Ford spec that differs from both Dexron and Type F. Can be replaced with Mercon or Mercon V. Mercon Ford fluid introduced in 1987, very similar to Dexron II. Okay for all earlier Fords except those that require Type F. As of July 1, 2007, the production and licensing of Mercon ATF by Ford ends. Ford says applications that require Mercon ATF can now be serviced with Mercon V. Mercon V Replaces Mercon. Mercon SP Latest friction modified ATF for Ford TorqShift Transmissions only. Do NOT use in transmissions that require Mercon or Mercon V. See Ford TSB 06144 for more information. Dexron General Motors original ATF for automatics. Dexron II Improved GM formula with better viscosity control and additional oxidation inhibitors. Can be used in place of Dexron. Dexron IIE GM fluid for electronic transmissions. Dexron III Replaces Dexron IIE and adds improved oxidation and corrosion control in GM electronic automatics. Dexron III (H) Improved version of Dexron III released in 2003. Dexron III/Saturn A special fluid spec for Saturns. Dexron VI Introduced in 2006 for GM Hydra Matic 6L80 6 speed rear wheel drive transmissions. Dexron VI now replaces Dexron III and II, and can be used in GM or import transmissions that formerly specified Dexron III or II. Chrysler 7176 For Chrysler FWD transaxles. Chrysler 7176D (ATF+2) Adds improved cold temperature flow and oxidation resistance. Introduced 1997. Chrysler 7176E (ATF+3) Adds improved shear stability and uses a higher quality base oil. Required for four speed automatics (do NOT use Dexron or Mercon as a substitute). Chrysler ATF+4 (ATE) Introduced in 1998, ATF+4 is synthetic and replaces the previous ATF+3 fluid. Used primarily for 2000 and 2001 vehicles, it can also be used in earlier Chrysler transmissions. ATF+3 should continue to be used for 1999 and earlier minivans because of the potential for torque converter shudder during break in. NOTE: Chrysler ATF+4 Must always be used in vehicles that were originally filled with ATF+4. The red dye used in ATF+4 is not permanent. As the fluid ages it may become darker or appear brown in color. ATF+4 also has a unique odor that may change with age. Therefore, do not relay on the color and odor of ATF+4 to determine if the fluid needs to be changed. Follow the OEM recommended service interval. Chrysler ATF+5 for 2002 and newer models. IMPORT APPLICATIONS: BMW LT7114l or LA2634 Special formula for BMW transmissions. Genuine Honda ZL ATF Special ATF for Honda automatics (except CVT applications). Mitsubishi Diamond SP II & SP Ill Special formula ATFs for Mitsubishi transmissions. Nissan J Matic Special formula for Nissan transmissions. Toyota Type T, T III & T IV Special formula ATFs for Toyota and Lexus transmissions. NOTE: There are a number of aftermarket synthetic ATF fluids that claim to meet numerous OEM requirements. Refer to the product label for approved applications. ATASA 5 th Bottom Line: Look It Up!
7. ATF may have special modifiers to work properly with the clutch & band surfaces. Fluidity Friction Dye
8. Additives to hold ATF are very important for shift feel, shift timing, shift quality & for lubrication. Viscosity Friction Freeze point
9. Dark particles in ATF are normally from or friction materials. Gear or Plate Band or Clutch Gasket or Sensor
10. Some manufacturers recommend that ATF & should be changed or flushed every 15K 20K miles! Filter Bands Clutches
11. A check of the parking to make sure the vehicle holds in park, a check for fluid, especially at the oil pan gasket & extension housing seal, a look at connections, prying around on the transmission and a look at the cooler lines are good 1 st checks during diagnosis. Brake, Leaks, Electrical, Mounts
NOTE: Poor engine performance, especially low engine vacuum can have a drastic effect on Automatic Transmission operation. Vacuum is a good indication of Engine Load
12. Before a road test, a technician should have referred to a & application chart.
13. is the term used to describe applying enough throttle to cause a downshift. Beat down Kick down Smash down
14. & may be problems with driveline components other than the transmission. Noises & Vibrations Odors & Smells DTC s & MIL s
15. Linkages, cables, modulator, and governor can all affect shift timing & feel. True or False
16. A test checks the holding capacity of the torque converter s stator overrunning clutch as well as the holding ability of the clutches & bands. Recall TSB Stall ** too high of a stall speed or never stalls = internal transmission member slippage ** too low of a stall speed = torque converter stator roller clutch is the problem
17. A transmission with a high stall speed indicates internal. A low stall speed is characteristic of a freewheeling torque converter stator roller clutch. Weepage Slippage Snippage ** too high of a stall speed or never stalls = internal transmission member slippage ** too low of a stall speed = torque converter stator roller clutch is the problem
18. A vehicle that stalls when put into reverse may have a locked torque converter (TCC). Clutch Stator Modulator
19. A pressure test measures the fluid pressure of different transmission at various speeds. Circuits Passages Valves
20. If the valve body is removed for service, keep it extremely clean, lube it with fresh, do not shop rag lint near it, torque it properly & never use gasket sealer on the separator plate gasket! Brake Fluid Transmission Fluid Coolant
21. are capable of being adjusted, some on the outside of the transmission case and some on the inside after removing the pan & filter. Torque the adjuster & then back it off to specs! Roller Clutches Bands Clutches
22. New clutch plates & bands must be in ATF for at least ½ hour before installation. Lightly Lubed Soaked Sprayed
Note: The PCM or the TCM is capable of storing transmission DTCs. A failed system will put the transmission into a default Fail Safe or Limp in Mode and turn on the MIL. Use a scanner to read DTCs.
Break Out Box Used to Test Solenoid Packs & Valve Bodys Resistances & Voltage Drops are Critical Measurements
Electrical tests: voltage available (should be battery voltage or charging voltage if running) voltage drop (.2 Volts maximum drop for any switch or wiring) resistance (shorted coil is less than specs, open = OL) current flow through actuators & wiring (decreased amps flow results in solenoids not fully switching = low fluid flow)
Pressure testing: Test at pressure taps with a 300psi gauge for mainline, throttle valve, governor psi Mainline pressure low = pressure regulator valve or pump issue Throttle pressure low = kickdown linkage/modulator valve/vacuum line /MAP issue Governor pressure low = stuck governor valve or VSS issue
Air testing: Apply compressed air (25 35 psi) to case & valve body passages to listen for clutch piston apply and retraction as well as servo operation. Pinpoints leaks, blocked passages, & bad check valves. A dull thud with air applied sounds good like the clutch piston or the servo moved. Hissing is an inside leak. Can be done with the trans in the vehicle & valve body removed or on the bench.
A "stall test" can be used on many older transmissions to check its ability to hold torque and the operation of the converter one way clutch. Some manufacturers do not recommend using a stall test because it stresses the transmission, so if you use this procedure, do not do it for more than five seconds at a time. Do not perform this test on vehicles that are equipped with a traction control and/or ABS systems. The inputs of a partially opened throttle, brakes applied, and no detectable movement by the wheel speed sensors will at best set a code, and at worst cause damage to the vehicle. Also, on electronically controlled transmissions that use vehicle speed sensor to determine shift points be prepared for a code to be set if you perform a stall test. Before conducting a stall test, check the fluid level and condition. Chock the wheels and set the parking brake. Start the engine and place the transmission in drive while holding the brake pedal under firm pressure so the vehicle does not move. Then push the accelerator to the floor while holding the brakes on. Note the maximum rpm the engine reaches. This is the stall speed. If it is lower than specifications, the torque converter one way clutch is slipping. If the stall speed is higher than specifications, the transmission is slipping. Possible causes include a low fluid level, restricted fluid filter, a sticking pressure regulator valve, slipping clutches, bands, shaft splines or one way clutch.
Automatic Transmission Stall Test
Purpose A Stall test is used to confirm transmission and torque converter problems by placing the maximum load on the transmission & torque converter.
Torque Converter Stall Torque converter stall should not be confused with a transmission stall test. Torque converter stall occurs when a locked torque converter causes the engine to stall. TC Stall can be caused by low fluid level, faulty torque converter controls or internal seals.
Hughes Performance HP HPPG35 Hughes Torque Converter, Street Strip 3500 RPM Stall Speed GM Aluminum Powerglide
Preliminary Check, Fluid Before stall testing, always make sure the fluid is in good condition and at the correct level. The fluid level should be between the minimum and maximum points on the dipstick, and the fluid should appear relatively clean and have a reddish brown color.
Preliminary Check, Shift Linkage With your foot firmly on the brakes, move the shift lever through the gear positions. You should feel the transmission internal detents as the gear position indicator (arrow) or see the instrument panel display the gear range.
Stall Test Always use extreme caution when stall testing a vehicle. Firmly set the parking brake Firmly apply the brake pedal. Use wheel blocks on at least 2 wheels.
Stall Test Cautions A stall test can: injure bystanders if the vehicle operator loses control. damage the vehicle if the vehicle operator loses control. overheat the transmission fluid if tested too long. burn out a clutch or band if it starts slipping. To prevent this: keep others away from the front or back of the vehicle. securely block the wheels and apply the brakes. limit tests to five seconds for each gear range. limit engine speed to a little above maximum stall speed.
Stall Test Cautions Do Not Perform A Stall Test On: Vehicles equipped with automatic traction control Electronically Controlled Transmissions
Stall Test 2 A stall test is performed by: 1. Firmly applying the brakes 2. Shifting the transmission into gear. 3. Depressing the throttle completely (5 seconds maximum!!). rpm increase to stall speed 4. Watching the tachometer to determine the stall speed. 5. Releasing the throttle for idle. 6. Recording the stall speed. 7. Repeat the test for each gear range.
Stall Test 3 Note that the transmission is in Drive, the vehicle is going 0 mph, the throttle is fully depresses and the engine speed is stalled at 2,300 rpm. This tells us that the driving and reaction devices for D1 are working properly.
Stall Test Cautions When stall testing an electronic transmission, use caution if testing while the EPC solenoid is disconnected Or, just don t do a stall test at ALL. Rely on other tests to determine conditions. The engine can possibly send enough torque to the transmission to cause damage.
Cool the Fluid in the Torque Converter Many technicians will shift the transmission into neutral and increase the engine speed to about 1,500 rpm after each test period. This allows a fluid exchange in the torque converter and moves the hot fluid to the transmission cooler.
Interpreting the Results Excessive engine speed during a stall test indicates slipping clutches in the transmission. A engine that is unable to reach stall speed lacks power or the torque converter one way clutch is slipping.
Interpreting the Results The stall speed was high only in D1. This transmission has a slipping one way clutch. The same driving member is used in M1 along with a second reaction member.
Interpreting the Results: High Stall Speed If all the stall speeds are higher than specifications, the problem is caused by a slipping apply device. Consult a clutch and band apply chart to determine which apply device(s) is effective in the gear range.
Interpreting the Results: Low Stall Speed If all the stall speeds are lower than specifications, the problem is caused by either: a faulty torque converter with a slipping one way stator clutch. a weak engine.
Fluid Pressure Test Many technicians will attach a pressure gauge while making a stall test. It helps determine the cause of high stall speeds.
Air Test Shop air can be applied to these ports to operate the various hydraulic components. Excessive leakage or no operation indicates seals on clutch pistons that need repair.
Some air nozzles use different tips that can seal openings or reach into hard to get to passages.