Issue Summary:
- Before and after a rebuild, the transmission may experience premature failure of the reverse, direct or coast clutch.
- The vehicle owner may complain of a delayed reverse and/or flare on the 3-4 shift and may feel bind-up in reverse and 4th. The unit may failsafe with a code for incorrect 4th-gear ratio.
- After a rebuild, the converter clutch may not operate, possibly producing code P0741, “converter clutch slippage detected.”
- BMW vehicles may exhibit a delay of two to 30 seconds from Park into Drive during the first cold start in the morning.
- The malfunction indicator lamp is illuminated with code 55 or P0735 stored for “Gear Ratio Error in 5th Gear.” There are no complaints of slipping or poor drivability. Some vehicles may suddenly exhibit a bind-up on the 1-2 shift.
Before and after a rebuild, the transmission may experience premature failure of the reverse, direct or coast clutch.
Inside the pump cover there are air-bleed ball capsules for each of these three clutches that may not be seating properly. If the unit originally came in with bad pump rings or converter-clutch failure, debris may be lodged in the capsule, preventing the air-bleed ball from seating and causing a leak in the circuit (see Figure 1).
The air-bleed capsule can be flushed out with air and mineral spirits. When finished, place drums onto an assembled pump and air-check to ensure that the balls seat with pressure.
The vehicle owner may complain of a delayed reverse and/or flare on the 3-4 shift in some instances and may feel bind-up in reverse and 4th. The unit may failsafe with a code for incorrect 4th-gear ratio.
Pump rings used to seal reverse-clutch and direct-clutch oil pressure are known to develop excessive wear, causing their respective clutch to slip or fluid pressure to cross into the wrong passage (Figure 2). The middle ring seems to be most prone to wear. This problem is usually attributed to pump misalignment. Pump alignment is critical. The pump is not a full circle, and misalignment is possible without proper care in assembly.
Replace rings and parts as necessary and align the pump. Inspect for high-line-pressure problems and correct if necessary. Inspect for direct-clutch-drum bushing wear and excessive end play, which would accelerate ring wear, and repair or adjust as necessary. In some instances the edges of the ring grooves in the aluminum drum support of the cover are rough and cut into the ring. Carefully dress the sharp edges of the ring groove with a fine file.
After a rebuild, the transmission may experience a problem of no converter clutch, possibly producing code P0741, “converter clutch slippage detected.”
Some pumps use a single TCC valve that can be placed into the pump incorrectly. The valve must go into the pump first, followed by the spring and retainer. If the spring is placed into the pump first, followed by the valve and retainer, the converter clutch won’t operate.
Install that valve correctly as shown in Figure 3.
BMW vehicles may exhibit a delay of two to 30 seconds from Park into Drive during the first cold start in the morning.
Models Affected:
- 325iA, 325xiA, 325xiTA, 330xiA, X5 3.0iA from 10/02 up to 12/03
- 325CiA, 325CicA, 330iA, 330CiA, 330CicA, 330i (HP), 325iTA from 03/03 to 12/03
Insufficient pressure boost for the C1 forward clutch during the first Park-to-Drive shift after extended (overnight) parking.
Reprogram the EGS control module using manual determination mode with DIS/GT1 CD 37 “SGC V2.1” online update (released 5/13/04) or higher.
Important: It is no longer necessary to replace the automatic transmission for this type of complaint.
The malfunction indicator lamp is illuminated with code 55 or P0735 stored for “Gear Ratio Error in 5th Gear.” There are no complaints of slipping or poor drivability.
The direct/reverse-clutch housing has cracked in the thrust-washer area where it contacts the pump (refer to Figure 4).
Replace the housing. Also, pay close attention to the overdrive accumulator, the seal sleeve in the case between the valve body and OD/intermediate-clutch housing and the #12 checkball, as these are other known causes.
Vehicles equipped with the 5L40-E transmission may suddenly exhibit a bind-up on the 1-2 shift.
One cause may be that the safety-mode valve in the valve body is stuck in an unstroked position. In first gear, this valve is held closed by spring tension. This allows line pressure to pass through the valve into the line-safety-mode circuit, which then strokes the 4-5 shift valve. The 4-5 shift valve then directs 123 oil into the 123 braking circuit, applying the low/reverse clutches with regulated line pressure for engine braking in first gear (see Figure 5).
When a 1-2 shift occurs, 1-2 signal oil, which becomes memory pilot pressure, is supposed to stroke the line-safety-mode valve, blocking the line-pressure feed to the 4-5 shift valve. But if the safety-mode valve cannot stroke, the low/reverse clutches remain on and a bind-up into second occurs (see Figure 6).
Clean the safety-mode valve and determine what other problem may have occurred to cause enough debris to stick the valve, and repair as necessary.
Safety-mode-valve strategy
The safety-mode-valve strategy is to allow for two failsafe gears, 4th and 5th. Should a fault occur while the vehicle is being driven, all solenoids will turn off and the vehicle will failsafe to 5th gear. But after an ignition cycle the vehicle will have 4th-gear failsafe.
The safety-mode valve is stroked by 1-2 signal oil when a shift into second occurs. When this happens, actuator-feed-limit pressure (solenoid-feed oil) is allowed to enter the memory circuit, which keeps the safety-mode valve in a stroked position (see figures 7 and 8). This also blocks line pressure to the 4-5 shift valve though the line-safety-mode circuit.
Once the safety-mode valve is stroked it remains stroked throughout 2nd, 3rd, 4th and 5th gears (see figures 9 and 10). When a shift into 5th occurs, the 4-5 solenoid turns off and 4-5 oil enters the overdrive-clutch-feed 2 circuit, applying the overdrive clutch. Pressure to the coast clutch is exhausted (see Figure 10).
And this is exactly what takes place when the vehicle defaults to 5th while being driven (see Figure 11).
But once the vehicle stops and the ignition is cycled, spring pressure forces the safety-mode valve closed. Line pressure passes through the valve and into the line-safety-mode circuit, where it strokes the 4-5 shift-control valve. And with all solenoids off, this blocks 4-5 oil from entering the overdrive-clutch-feed 2 circuit, placing the vehicle into a 4th-gear failsafe (see Figure 12).
Note: This bulletin explained that if the safety-mode valve should stick in an un-stroked position a bind-up in 2nd would occur. But if this valve should get stuck in a stroked position, a loss of engine braking in first gear might occur. If the vehicle fail-safes, it will have 5th gear even after an ignition cycle.
July 2007 Issue
Volume 24, No. 7
- 5L40-E: Premature Failure of Reverse, Direct and/or Coast Clutch
- 5L40-E: Delay or Bind-up in Reverse; Flare or Bind-up into 4th
- 5L40-E: No Converter Clutch
- BMW 5L40-E: Delayed Engagement from Park to Drive on Cold Start
- GM 5L40-E/BMW A5S360R: 5th-Gear-Ratio Codes
- GM/BMW 5L40-E: 1-2 Bind-up (Safety-Mode-Valve Strategy)