1. Automatic Transmissions and Transaxles CHAPTER Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch SIXTH EDITION Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Valve Bodies and Valve Body Service 16

2. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–1 A typical valve body as installed on a GM 4T65-E transaxle.

3. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–2 A typical upper valve body showing the fluid passages (“worm holes”).

4. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Frequently Asked Question How Long Does It Take for a Shift to Occur? In most electronically controlled automatic transmissions and transaxles, the shift command from the PCM/TCM occurs in less than 0.35 seconds and the shift is completed within 0.9 seconds.

5. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–3 A rooster comb is the detent that helps retain the manual valve in the various positions in the valve body.

6. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–4 A typical shift valve has a spring to move the valve to a downshift position where the throttle pressure works with this spring. When governor pressure gets high enough, the valve will move to an upshift position.

7. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–5 Operation of the valve controls fluid flow to the actuator. It can (a) block operation, (b) cause apply, or (c) cause release.

8. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–6 A check valve is opened by fluid flow in one direction (left) and closes when the fluid tries to flow in the reverse direction.

9. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–7 Check balls are used in the valve body to allow hydraulic circuits to share a common passage.

10. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–8 When fluid flows through this shuttle valve from port B to port C, the check ball moves over to close port A (left). Fluid flow from port A will close port B (right).

11. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Tech Tip Do Not Use a Magnet on Check Balls It is easy to use a magnet to retrieve the steel check balls out of the pockets in the valve body. However, using a magnet or placing the steel check balls in a magnetic tray may cause them to become magnetized. If the balls become magnetized, they may be attracted to the steel separator plate and not be free to move to block passages as designed.

12. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–9 (a) An orifice will cause a pressure drop as fluid flows through; (b) when the flow stops, the pressure on both sides of the orifice will be the same.

13. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Frequently Asked Question What Does an Accumulator Do? An accumulator is a piston or valve that is not attached to anything because all it does is move in its own bore and is usually located in the valve body. An accumulator is tied to an apply piston by a branch of the fluid passage used for apply pressure. It is designed to move at a pressure just above that needed to move the apply piston. Just after the apply piston takes up the clutch or band clearance and the fluid pressure starts to increase, the accumulator piston moves and absorbs some of the fluid flow. This causes a lag in the pressure increase at the band servo and clutch. The effect is a slightly longer and smoother (cushioned) shift. SEE FIGURE 16–11 on page 270.

14. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–10 A typical valve body showing some of the valve and solenoids as well as the clips and pins used to retain the parts in the valve body.

15. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–11 The accumulator for the forward clutch is shown at the lower right part of this valve body.

16. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–12 Shift valves move when there is a difference in pressure. In a hydraulically controlled automatic transmission/transaxle, the shift valves compare governor pressure force against throttle valve (TV) pressure force to determine when to upshift or downshift.

17. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Real World Fix The Case of the Stalling Ford A 2000 Ford Mustang (61,000 mi) came in with a complaint of stalling when shifted to drive after the transmission warmed up. A scan-tool check showed no unusual activity of the shift or TCC solenoids. The TCC solenoid seemed sticky so it was replaced along with the Manual Lever Position Sensor (MLPS), which did not help. The valve body was checked, and several of the aluminum valves were severely scored and worn. Valve body replacement fixed this problem.

18. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Tech Tip Technician-Made Valve Body Organizer Some technicians make a valve organizer by folding a piece of cardboard into an accordion shape. The biggest problem during valve body repair is getting it back together with everything in the right order and location and using something like this helps with the organization. SEE FIGURE 16–13.

19. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–13 A sheet of stiff paper has been folded to create this simple valve holder. Note that a valve group can be placed in order and be labeled.

20. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–14 In an old hydraulically controlled automatic transmission/transaxle, the valve body contains valves that control fluid pressure and flow to various apply devices that, in turn, produce proper shifts at the proper time.

21. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–15a An exploded view of the valve body from a four-speed transaxle. Note the various valve groups and how they are retained in their bore.

22. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–15b A cutaway view of the valve body from a four-speed transaxle. Note the various valve groups and how they are retained in their bore.

23. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Frequently Asked Question How Is a Solenoid Tested That Has a Diode Across the Leads? Some solenoids include a diode to eliminate voltage spikes that might occur when the solenoid is deenergized. As the solenoid is tested, the diode is also checked to see if it allows a flow in one direction but not in the other. Measure the solenoid coil resistance with the analog (needle-type) ohmmeter, the reading should be about 20 to 40 Ω depending on the coil temperature. If the reading is less than 20 Ω, the coil or diode is shorted. If the reading is greater than 40 Ω or infinite, there is an open or broken circuit. In either case, the solenoid is faulty. To check the diode, reverse the meter leads. The meter reading should now be lower than it was before, usually about 2 to 15 Ω. If the reading does not change, the diode is open or shorted, and the solenoid is faulty.

24. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–16 If the valve body is moved to a vertical position, steel valves should slide freely from the bore. Be prepared to catch the valves when making this check.

25. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–17 A valve body being washed and air dried in a parts washer. It will be cleaned again when the two major parts are separated.

26. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Tech Tip Solenoids Are Wear Items Many technicians consider solenoids, especially PWM solenoids, to be “wear items” and automatically replace them if the transmission experiences problems after about 90,000 miles (150,000 km).

27. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–18a Ohmmeter A is checking for a grounded solenoid coil; the reading should be infinite. Ohmmeter B is measuring the coil resistance; it should be within the specifications for this solenoid.

28. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–18b Connecting a solenoid to a 12-V battery should cause it to operate. Make sure the battery is connected using the correct polarity in case the solenoid has an internal diode.

29. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–19 Air should not be able to flow through this solenoid if it is not activated. If it is connected to a 12-V battery, it should make a “click,” and air should be able to flow through it.

30. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–20 Using assembly lube is a great way to keep check balls in place during the reassembly of the valve body.

31. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–21 The valve body bolts should be tightened in order, starting from the center and working in an outward spiral.

32. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch Tech Tip The Shop Light Trick If a faulty check ball–transfer plate seat is suspected, place the ball on its seat and hold a flashlight behind the transfer plate. Light shining between the ball and the transfer plate indicates a problem. SEE FIGURE 16–22.

33. Copyright © 2015 by Pearson Education, Inc. All Rights Reserved Automatic Transmissions and Transaxles, 6e James D. Halderman | Tom Birch FIGURE 16–22 A check ball should seal off light from coming through the spacer plate. A problem is indicated if light shines through an opening alongside of the check ball.