Issue Summary:
- After overhaul, a BMW or 2000 or later Isuzu with the 4L30-E has no reverse and binds in second gear.
- A ZF 6HP26 appears to be leaking from the area of the pan gasket.
- After overhaul, a Saturn Ion or Vue that came in with a flared 2-3 shift still has the 2-3 shift flare, and now there is a flare on the 3-4 shift and shifts are erratic and harsh.
- A Saturn S Series comes into the shop with code P1624 set and a code definition of “Customer Snapshot Data Available.”
After overhaul, a BMW or 2000 or later Isuzu with the 4L30-E transmission exhibits a complaint of no reverse and binds in second gear.
One cause may be a missing checkball in the adapter-case housing.
BMW and 2000-up Isuzu vehicles use a “reverse-inhibit” feature to prohibit application of the reverse clutch and prevent the possibility of damage to transmission components while the vehicle is being driven in forward ranges. If the computer detects that reverse gear has been selected with forward vehicle speed above 7 mph, the TCM will energize and activate the torque-converter-clutch solenoid, allowing the “reverse inhibit” valve in the center support to move into a position that will block reverse-clutch oil from applying the reverse clutch.
Refer to Figure 1 for location of the checkball in the adapter-case housing and the spacer-plate identification.
Refer to Figure 2 for a diagram of the BMW and 2000-up Isuzu center-support assembly that uses the reverse-inhibit valve.
If during overhaul you omit the checkball in the adapter housing, two things will occur: The transmission will have no engagement in reverse, and it will bind up on the shift into second gear. To see how this occurs, refer to the partial hydraulic diagrams in figures 3, 4, 5 and 6.
Figure 3 shows the ball properly installed in the adapter housing. Note that the ball seats against the separator plate and forces oil into the reverse-clutch circuit through the reverse-inhibit valve, then applying the reverse clutch while at the same time blocking oil from entering the second-clutch circuit.
Figure 4 shows the housing with the checkball omitted. With no checkball to seat against the plate, reverse-oil pressure passes into the second-clutch circuit. Oil pressure flows through the 1-2/3-4 shift valve and exhausts at the 2-3 shift valve, resulting in the neutral condition.
Figure 5 shows the ball properly installed and the transmission in second gear. Note that the ball seats against the plate and blocks oil from entering the reverse-clutch circuit.
Figure 6 shows the housing with the checkball omitted. Oil pressure is allowed to enter the reverse-clutch circuit, causing the reverse and second clutches to apply together and resulting in the bind-up on the shift.
Install the checkball in the adapter housing.
The transmission appears to be leaking from the pan gasket (Figure 7).
The Mechatronic sealing-sleeve O-rings (Figure 8) are leaking and oil is running down along the pan rail, giving the appearance that the pan gasket is leaking.
Replace the Mechatronic sealing sleeve.
- Mechatronic sealing sleeve . . . ZF part number 0501212190
- Oil pan/filter assembly for manual valve body . . . . . . . . . ZF part number 0501215789
The vehicle came in with a flared 2-3 shift. After overhaul, the 2-3 flared shift is still present, there is now a flare on the 3-4 shift and the shifting is erratic and harsh.
The 2-3 flare is due to aeration of the transmission fluid resulting in a delayed application of the third clutch.
The 3-4 flare and the erratic and harsh shifts are caused by the failure to do a mandatory TCM relearn procedure (Figure 9).
After completing the relearn procedure, drive the vehicle and see whether the shift complaints are gone. If any of the complaints are still present, a reflash may be in order, and in some instances replacement of the valve body may be necessary, depending on transmission and revision part number (Figure 10).
GM suggests that the valve body be replaced first, after which the vehicle should be driven to re-evaluate the shift quality; then, if necessary, reflash the TCM.
Check the identification tag on top of the transmission for the part number (Figure 11), and compare it with the chart in Figure 10.
A Saturn S Series comes into the shop with code P1624 set and a code definition of “Customer Snapshot Data Available” (Figure 12).
Saturn S Series vehicles from 1996 to 2002 have the ability to store a “freeze-frame” snapshot of a problem that the PCM detected but has not set a hard code. In other words, it is a “pending code,” which means it has not yet met the failure criteria to become a hard code and will not be stored in the PCM memory. However, one data frame will be stored as a freeze-frame snapshot.
This allows the technician to capture an intermittent drivability malfunction that may be difficult to duplicate while driving the vehicle.
Note: Only cars with cruise control have this ability. This is because to retrieve the stored freeze frame, you must cycle the cruise control on/off switch (Figure 13) three times within three seconds from the time the ignition is turned on.
See whether the single freeze frame that is retrieved can lead the technician to the appropriate repairs. Use your scan tool and scan for pending codes just in case one has been set. Pending codes usually are stored in the “OBD-II Global” library of your scan tool.
March 2009 Issue
Volume 26, No. 3
- 4L30-E: BMW, 2000 and Later Isuzu: No reverse; binds in 2nd
- ZF 6HP26: Fluid Leak
- Saturn Vue and Ion: 2-3 Flare
- Saturn S Series: Code 1624