Issue Summary:
- Ford vehicles from the 2004 model year up equipped with the 4F50N transaxle may exhibit a 1-2 slide bang before or after overhaul.
- 1999-and-up Ford vehicles equipped with the AX4S transaxle may exhibit a 1-2 neutral condition after overhaul.
- Before or after overhaul, a BMW/Isuzu with the 4L30-E transmission exhibits soft or flared upshifts, slipping or gear-ratio-error codes.
- A 2007 GMC Acadia, Buick Enclave, Pontiac G6, or Saturn Aura or Outlook equipped with a 6T70 transaxle may develop a problem illuminating the “Check Engine” lamp, with one or more codes present.
2004 and newer Ford vehicles equipped with the 4F50N transaxle may exhibit a 1-2 slide bang before or after overhaul.
The cause may be a cracked intermediate piston, as shown in Figure 1, or a weak 1-2 capacity-modulator-valve spring.
Note: 2004-and-up 4F50Ns are equipped with the 1-2 capacity-modulator valve that controls the rate of application of the intermediate clutch, like the previous 1-2 capacity-modulator valve on the AXOD/AX4S (Figure 2).
To correct this condition, replace the intermediate piston with an updated piston from Ford or from your parts distributor, as some distributors sell the OE pistons. Install a heavier spring into the 1-2 capacity-modulator-valve line-up.
Note: The 2-3 capacity-modulator-valve spring is the same as the 1-2; if a firmer 2-3 upshift is desired, a firmer spring can be used there also. See Service Information for available after-market replacement springs.
Note: The 1-2 and 2-3 capacity-modulator-valve springs are identical, so two aftermarket springs can be used to cover second- and third-gear shift feel per transmission overhaul.
An updated piston can be identified by the engineering number printed on the bottom side of the piston (Figure 1). This number is slightly different from the part number.
- Updated intermediate-clutch piston . . . . . . . . . . . . . . . 4F1Z-7E005-AA
- Superior 1-2/2-3 capacity-modulator spring kit . . . . . . . . . . . . K084
- Sonnax 1-2 capacity-modulator spring . . . . . . . . . . . . . . . . 96201-27
1999-up Ford vehicles equipped with the AX4S transaxle may exhibit a 1-2 neutral condition after overhaul. Valve-body inspection determines that the 1-2 capacity-modulator valve is not sticking.
The cause may be that during overhaul the pump had to be replaced because of typical pump-shaft-bearing and rotor failure and a replacement pump body with a 1998-and-earlier spacer plate was used. The 1999-up pump plate requires three checkballs, and when the B5 checkball is left out when the previous-design spacer plate is used, L12 pressure will be lost at the manual valve, through the reverse circuit.
Refer to Figure 3 to identify the previous-design pump body and pump spacer plate.
Refer to Figure 4 to identify the 1999-up pump body and pump spacer plate to ensure that the plate with the correct checkball locations is used.
Before or after overhaul, a BMW/Isuzu with the 4L30-E transmission exhibits a complaint of soft or flared upshifts, slipping, or gear-ratio-error codes stored. A line-pressure check indicates pressure is not increasing properly with throttle opening, and an electrical check shows proper amperage drop in the EPC-solenoid circuit.
One cause may be a worn feed-limit-valve bore in the adapter-case valve body.
The responsibility of the feed-limit valve is to regulate line pressure before it is fed to the force-motor/pressure-control solenoid. As the valve bore wears, the valve and spring will lose their ability to regulate properly. As bore wear becomes more severe, excessive exhaust of line pressure occurs, creating the soft or flared shifts, slipping and other complaints.
Refer to Figure 5 for a diagram of the adapter-case valve body, and a partial cross-sectional view of the feed-limit valve, showing the location of bore wear.
Replace the adapter-case valve body.
A 2007 GMC Acadia equipped with a 6T70 transaxle may develop a problem illuminating the “Check Engine” lamp, with one or more of the following codes being set: P0716, P0717, P0722, P0723, P0751, P0756, P0776, P0796, P2714 and P2723. A 2007 Buick Enclave, Pontiac G6, or Saturn Aura or Outlook also may develop this same complaint.
The input- and/or output-speed sensor is faulty.
Use a scan tool to check input and output speed and replace the defective speed sensor(s).
To replace the input- or output-speed sensor, you will have to remove the valve body. Remove only the shaded bolts shown in Figure 6 to remove the valve-body assembly.
The locations of the speed sensors are explained in Figure 7.
There have been problems with the input- and out-put-speed sensors while the unit is still under the factory warranty. Refer to factory bulletin 07-0730-019A.
- A/T input-speed sensor . . . . . . . . . . . . . . .4223891
- A/T output-speed sensor . . . . . . . . . . . . . . .238337
Special Note: You must take care when dropping the frame to gain access to the transmission not to let the splined steering knuckle slip out of the steering rack. If this should occur, after reassembly the steering wheel will rotate continuously and could cause damage to the clock springs, setting a variety of codes.
February 2009 Issue
Volume 26, No. 2
- Ford 4F50N: 1-2 slide-bang
- Ford AX4S: 1-2 neutral in 1999 & later models
- BMW/Isuzu: 4L30-E inadequate line pressure
- GM 6T70/75: Issues with input-/output-speed sensors