Transmission

How to switch to neutral

BMW E70

 

 

Troubleshooting (by symptom)

  • Tips.
    • If vehicle doesn’t move in drive or reverse, the problem is likely mechanical.
    • If vehicle moves, but doesn’t shift correctly, problem is likely electrical.
No Shift ⇢ First Gear
  • Transmission is not shifting out of first gear
    • “LIMP MODE”
      • Case Study. 2006 Toyota Tundra SR5 4.7L
        • DTC’s: P2440- 2nd switching valve stuck open bank one,
          P1441- 2nd air valve stuck open,
          P1444- 2nd air valve stuck open
          After codes are cleared, transmission shift normally until codes come back.
          Bad air pump and valves will put transmission into a limp mode, to force driver to stop and repair the car, thus preventing damage to the catalytic converter.
          The trick to avoid limp mode temporarily is to disconnect air pump connectors and clear codes. CEL will be on, but limp mode will be off.
    • Worn Clutches
      • Quick test. Put transmission into manual first gear. Additional pressure applied to the clutch when manual first gear is selected may be enough to allow the vehicle to move. If vehicle moves, then clutches are worn for sure.
No Shift ⇢ Reverse
  • No Shifting Into Reverse, Other Gears Shift Ok
    • No engine braking in 3 lower gears
      • Broken snap ring for the direct clutch in the overdrive section
    • No engine braking in manual low only
      • Reverse servo is broken
      • Band is toasted

 

Incorrect Shifting. Erratic, bumpy, slipping shifts.

 

Stalling ⇢ When Pulling to a Stop
  • Stuck TCC solenoid
    • More frequently in warm weather

 

Poor Acceleration ⇢ From Standstill
  • Slipping stator clutch

 

Poor Acceleration ⇢ at Highway Speed
  • Seized stator clutch

 

Rough Idle ⇢ In any gear, not in park or neutral
  • Wrong/Defective Torque Converter
    • Perform a TC Stall Speed Test
    • MAP might indicate heavy engine load

 

Shifter Issues

  • Shifter can be moved into “Drive” position, but cannot be moved back pass “Neutral”
    • No signal from ABS unit (e.g. 13′ Subaru Crosstrek)
  • Shifter can not be moved out of “Park”
    • Shifter knob is not fully settled down in the right position  (e.g. Subaru)
    • Brake switch circuit

 

Transmission Light is Blinking

  • “AT Oil Temp” light is blinking with no codes? | Subaru
    • If it’s a CVT, perform “CVT Learning”.
      • Battery disconnect might have caused  adaptation values to be cleared (10-11 Outback/Legacy)

 

Troubleshooting (by component)

 

Shifter
Shifter Solenoid
  • Shifter Solenoid | Honda
    • Solenoid might get overheated and get stuck, that would cause transmission damage in a very short period of time, like overnight.
Torque Converter

Stator (w/ One Way Clutch)

  • Slipping Stator Clutch
    • The stator in being able to move backwards allows the out flow to end up being directed back at itself. That is surely the reason for the greatly reduced stall speed and poor output power to the transmission input shaft. (Dennis from Automatic Transmission Rebuilders Association)
    • In an event of a freewheeling stator, the stator cannot redirect the fluid resulting in little to no acceleration of the vehicle. (U.S. Army TARDEC Fuels and Lubricants Research Facility)
      • Case Study. 2010 SsangYong Kyron (with Benz System)
        • Car doesn’t move uphill from a standstill at all. On a flat ground, there is a power lag, then picks up and drives like normal.
          • If it were an engine performance problem then accelerating after decelerating from 50 mph to 30 mph would show a performance problem too.
          • The description of the problem sounds like what happens when the stator one-way clutch fails and the stator is no longer redirecting the fluid at initial acceleration so the torque multiplication that normally happens at take off isn’t happening. This stator one-way clutch failure will make for poor acceleration from a stop, slightly sluggish slow speed acceleration and normal feeling acceleration at all other speeds.
  • Seized Stator Clutch
    • Seized stator clutches (no overrun) can cause the engine to labor big time approaching coupling point.
Lockup Clutch (TCC)
  • The engagement of this clutch causes the engine to lock to the transmission input shaft thereby leading to a direct 1:1 drive ratio.
    • The Lockup Solenoid duty cycle should go to 0 percent when the Throttle Position Sensor is above 40 percent and should return to 100 percent when the throttle is returned back to 15 to 20 percent.
    • The Lockup Solenoid duty cycle should go to 0 percent whenever the brake pedal is applied, regardless of speed.
    • The duty cycle should go to 0 percent whenever the throttle is fully released and the vehicle has decelerated below 30 MPH.
Valve Body
  • Replacing TCM or Valve Body
    • BMW | Mini
      • If Transmission Control Module (EGS) or CAS (Immobilizer) are swapped, need to perform ISN matching.
        • Read more in Immobilizer ➱ BMW ➱ Changing ISN in the EGS
      • Mini Cooper
        • Requires “Transmission Relearn”
    • Chrysler | Dodge | Jeep
    • GM
      • TCM is inside the transmission (e.g. 2007 Yukon)
        • TCM is replaceable together with valve body (inside tranny) as one unit.
        • Required SPS Programming
        • Calibration Using Tech2Win → Transmission → Module Setup → Clutch Calibration (?)
          • To do calibration tranny needs to be warmed to 70 degrees C.
          • If during calibration check engine comes on with “TCC Pressure Solenoid Circuit” code and tranny stops shifting completely, disconnect the battery for a min.
          • Calibration will fail if this code is current  (warm up tranny, disconnect battery to get rid of the code and do calibration again).
      • TCM is a separate computer (e.g. 2003 Express)
        • TCM needs to be programmed through SPS.
          • Solenoid codes and communication codes might be present due to the lack of programming.
    • Honda
      • New TCM will need to be reprogrammed through J2534 (17’ civic).
        • Otherwise, PCM will have a code about communication issues with tranny and shifter indicator will be off.
    • Mercedes
      • Need SCN coding to program new TCM/Valve Body/ Electric Plate.
        When the new electrics plate /control unit/valve body is fitted to the transmission you must carry out the full initial start up process straight away. If the vehicle is started and driven without the initial start up process fully completed, the vehicle will start and drive in emergency mode only. The control unit will be locked out, and it will not be possible to complete initial start up of the electric plate/valve body/ ECU. THIS WILL RENDER THE CONTROL UNIT UNSERVICEABLE.
    • Kia
      • Requires “Clear Adaptation Values” (e.g. 15′ Kia Rio)
Wave Plate
  • Main symptom is high rpm shifting
  • No shifting at all, reverse or drive
Oil Pump

 

 

Tests

Scan Tool Test

  • Monitor the Converter RPM (Slip) and compare that to Input Shaft speed RPM at greater than 45 MPH on a smooth, flat surface after the vehicle is warmed up and the fuel system is in a closed loop.
  • Monitor how the Converter Lockup Solenoid responds to an increased amount of throttle.
    • The Lockup Solenoid duty cycle should go to 0 percent whenever the brake pedal is applied, regardless of speed.
    • The duty cycle should go to 0 percent whenever the throttle is fully released and the vehicle has decelerated below 30 MPH.
    • The Lockup Solenoid duty cycle should go to 0 percent when the Throttle Position Sensor is above 40 percent and should return to 100 percent when the throttle is returned back to 15 to 20 percent.
  • When looking at the Toque Converter RPM versus the Input Shaft RPM, observe if the scan tool data has a Converter Slip Speed PID.
    • If the Lockup System is functioning correctly, the Slip Speed value should never be above 50 RPM. Try gently depressing the throttle on a gradual incline above 45 mph. When doing this, the Slip Speed should not increase. If it does and the Lockup Solenoid duty cycle is 100 percent—meaning it is fully applying the converter clutch—then you know you have a slipping Converter Clutch.
    • If the Slip Speed stays steady but the transmission Output Shaft Speed starts to decrease (along with the MPH), then you know that you have an internally slipping transmission, usually caused by worn Clutch Packs or Sprag 1-Way clutches.
    • If the Slip Speed remains very high and the Lockup duty cycle is 100 percent, then it is likely that the Solenoid, Wiring, or PCM is defective, because the duty cycle is reporting that the PCM is commanding the Lockup System to apply, but there is no change. Even with worn out Converter Clutches, there is always some kind of Slip Speed reading. It may go very high whenever the throttle is applied, but there should be some kind of a RPM reduction between the Converter Speed and the Input Shaft speed that verifies the Lockup Solenoid and PCM are trying to do their jobs.

 

Stall Test

  • Drive the vehicle until normal operating temperature is achieved.
  • Check the stall speed specifications, for your vehicle.
  • Firmly press brakes and depress accelerator pedal to the floor.
  • Observe the maximum engine speed (rpm). This is a stall speed.
    • If the rpm is higher than specifications, a holding clutch or band is slipping.
    • If the rpm is lower than specifications, the torque converter is defective (one way clutch or stator is slipping) or the engine is not producing normal output.

 

RPM Test

  • Drive on the steady cruise about 50MPH.
  • While maintaining constant speed with your right foot on accelerator, gently apply brake pedal with your left foot to open electrical circuit for the TCC through the brake switch.
  • TCC will disengage and the RPM should increase about 150 to 250 rpm and then drop back when the brake pedal is released. This RPM change is your proof that TCC is working.

 

Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments
0
    0
    Your Cart
    Your cart is emptyReturn to Shop