Originally Posted by
Steven@HPTuners
There are still just the 4 main states, but there are many modes that occur while targeting those 4 states.
The TCC Mode shows the state of the actual converter clutch pressure controller itself, which may be on some in between states or be a bit more specific.
The modes you can see here are:
Init - I doubt you'll have a chance to see this mode, its only during startup while it first loads it.
Open - The clutch is empty, fully open.
Apply Ramp - Clutch Pressure is being ramped to fill pressure
Apply Fill - Clutch Pressure is steady to fill the clutch volume
Apply Comp - Clutch pressure compensation is occurring (adapting the clutch volume)
Slip SS - Clutch pressure is regulated to a target slip, with no dynamics occuring
Slip - Clutch pressure is regulated to a target slip, with dynamics occuring
Load Free - There is no load on the converter clutch, pressure is being held to just keep the clutches together
Locked - The converter pressure is controlled to ideally have 0 slip, but can have up to 5rpm of slip. This is actually what "locked" is for almost all transmissions. Its an ideal state of 0 slip, but the pressure is actively being controlled to be the minimum necessary, so some minor slip happens. This is usually how all transmissions work, and the reason is to minimize pumping loss inside the transmission for maximum efficiency
Overlocked - The converter pressure is set to target EXACTLY 0 slip by using an offset/maximum pressure. Instead of using closed loop regulation like normal Locked, this uses maximum pressure. This increases pumping loss of the transmission oil pump, so its only used when necessary to maintain efficiency.
Lock to Slip - The converter is transitioning from a lock or overlock state to a slip state.
There are two additional modes that can happen during Unlocked/Open operation, these are both used to test/verify torque converter operation without causing the clutch plates to ever come into contact.
Open Pressure Ramp - Verifies that pressure can be controlled by the TCM at a set rate. If this fails, a code is set for torque converter clutch pressure control.
Open Current Ramp - Verifies that the torque converter pressure control solenoid works correctly. If this fails, a code is set for TCC solenoid failure.