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.
- 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
- 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.
- 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.
- 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.
- Requires “Clear Adaptation Values” (e.g. 15′ Kia Rio)
- Main symptom is high rpm shifting
- No shifting at all, reverse or drive
- Variable Capacity Oil Pump
- Line Pressure high/ low DTC
- Bad ECM
- Bad Tranny or line pressure solenoid
- Try “Clear learned variable line pressure (VLP) counters”. All of them (2010 Jeep Wrangler).