Manual Updates for A Couple of Mazda Valve Bodies On occasions technicians may find themselves fighting a loss of line pressure rise with a GF4A-EL transaxle. The transmission has been unplugged and line pressure still does not rise verifying that there is in fact an internal transmission concern. The pressure control solenoid has been replaced, the pump and spool valve has been inspected and determined to be in proper working order, and the pan has not been pushed up into the newly installed filter. The valve body is removed and the pressure regulator valve is also looking good. At this time a set of hydraulics are reviewed and it is discovered that there is a Pressure Modifier Valve in the pressure control system (See Figure 1). Consulting a picture of all the valve locations and their identification reveals that no where in the break down is this valve identified in any way. An oversight that has puzzled many for years. Figure 2 provides the location of this valve line up and can be easily identified by the adjusting screw in the end plug as seen in Figure 3 ( ). Should this Pressure Modifier Valve be stuck or the bore is wore, a no line rise condition will occur. So be sure to update the manual in your library with the identification of this valve and its’ location. Another manual update that would be good to make is with the F4EAT transaxle. The 2-3 Shift Valve and the Bypass Valve are side be side near the inlet port of the valve body as seen in Figure 4. These valves have been oppositely labeled. This error can lead to a no 2-3 up shift problem after overhaul. The reason for this is that many technicians peg the bypass valve to allow for a firmer 2-3 shift. This works with the G4A-EL, the GF4A-EL and the F4EAT transaxles alike. If a technician is unaware of the mislabeling of the valves in F4EAT valve body information, the 2-3 shift valve is unknowingly pegged preventing the 2-3 shift to take place.  One way to remember the correct valve is that the Bypass  Valve is closet to the inlet and that the 2-3 Shift Valve is the larger of the two. The depth of this adjusting screw is usually in the vicinity of 0.012” from the surface of the plug from the factory. Over adjustment of the screw has been known to cause uncomfortable coast downshift clunks

X • • • • • • X SOLENOID REDUCING PRESSURE COAST CLUTCH PRESSURE TO BYPASS VALVE LINE PRESSURE FROM 1-2 SOLENOID 1-2 SOLENOID "OFF" TO TCC SOLENOID PRESSURE CONTROL SOLENOID "OFF" TO 2-3 TIMING VALVE TO PRESSURE MODIFIER ACCUMULATOR "NO" CUTBACK PRESSURE APPLIED TO CUTBACK VALVE x x CUTBACK VALVES PRESSURE MODIFIER VALVE x x x • • • • A B PRESSURE REGULATOR VALVE Figure 1

Figure 2 Figure 3

Figure 4 Bypass Valve 2-3 Shift Valve