Launch Control

Warning

Launch Control is a motorsport orientated function can lead to transmission and/or other driveline component damage if not used correctly.

Overview

Launch Control can be configured in a variety of way depending on the desired control outcome.

Launch control can be configured to:

Control clutch torque and clutch torque rate.
Generate an Engine Speed Target to be sent to the engine.
Generate a torque limit to to be sent to the engine.

There are 5 main states/phases the Launch system can be in:

Disarmed → Armed → Static → Preload (optional) → Moving

State	Meaning
Disarmed	Off, or arming conditions not currently met.
Armed	Arming conditions met, waiting for launch lockouts to clear.
Static	Car stationary, launch active. Clutch is typically held open/slipping to a torque target.
Preload	(Optional) Clutch is pre-loaded to a torque target for a fixed dwell time before the final dump.
Moving	Clutch torque is actively controlled through the launch. Ends when a disarm condition is met.

Clutch Control

The primary function of Launch Control is to override the clutch pressure by generating a clutch torque request.

Clutch Control is enabled in Launch Control Setup.

Launch Control never engages a clutch that isn’t already part of the currently selected gear. It can only override the pressure target of a clutch the TCM has already activated for that gear. It cannot bring in an extra clutch on its own.

Launch Control Clutch Select

Care should be taken to ensure the Launch Control Clutch Select table is set up correctly. In most case the table will be identical to the Takeup Clutch Select table.

Important

The Clutch Select table’s X axis MUST be Clutch #. The table is re-evaluated each time the system re-arms into the Static phase. This allows the table’s Y axis to be another channel such as Gear.

When Clutch Control is disabled, Launch Control does not touch clutch pressure at all — only the engine RPM target / torque limit outputs (if enabled) are active.

Arming & Disarming

Arming

The system arms when every configured arming condition is simultaneously true. Each condition is independently optional (Eg: 0 = OFF). Enable only the conditions relevant to your application.

At least one condition must be configured, or the system will report “Disarmed - No Config” and never arm.

Condition	Enable via	Threshold
Launch Switch	Launch Arming Switch = ON	`Launch Arming Switch` = ON
Brake Switch	Brake Switch Arming = ON	`Brake Switch 1` = ON
Brake Pressure	Arming Brake Pressure Minimum > 0	`Brake Pressure Front` > Threshold
Transbrake Switch	Transbrake Switch Arming = ON	`Transbrake Switch`= ON
User Function	Arming User Function ≠ Off	`User Function # Status` = ON

Static → Moving

Releasing any configured arming condition while in Static or Preload is what triggers the transition into Preload/Moving.

Lockouts (Armed → Static)

Once armed, the system waits for all configured lockouts to clear before entering the Static phase.

At least one lockout must be configured, or the system will report “Lockout - No config” and will not enter Static.

Lockout	Enable via	Condition to clear
Gear	Always active	`Gear` ≥ 1st
Clutch By Wire	Always active	CBW must not be active
Pedal/throttle position	Static Lockout Pedal/Throttle Position > 0	`Pedal Position`* ≥ Threshold
Output Shaft Speed	Static Lockout Output Shaft Speed > 0	`Output Shaft Speed` < Threshold
Drive Speed	Static Lockout Drive Speed > 0	`Drive Speed` < Threshold
Engine speed	Static Lockout Engine Speed > 0	`Engine Speed` > Threshold
User Function	Static Lockout User Function ≠ Off	`User Function # Status` = ON

* If Pedal Position input is not configured, Throttle Position is used.

Disarming (Static / Preload / Moving → Disarmed)

While active, the system aborts back to Disarmed immediately if:

The TCM begins a shift.
The gear selector leaves Drive/Manual (enters Park/Neutral/Reverse)
Any one of the following (each optional) stays true for longer than the Disarming Time (ms):

Disarm condition	Enable via	Trips when
Pedal/Throttle Position	Disarming Pedal/Throttle Position > 0	`Pedal Position`* < Threshold
Output Shaft Speed	Disarming Output Shaft Speed > 0	`Output Shaft Speed` > Threshold
Drive Speed	Disarming Drive Speed > 0	`Drive Speed` > Threshold
Engine Speed	Disarming Engine Speed > 0	`Engine Speed` < Threshold
Clutch Slip	Disarming Clutch Slip > -1000	`Clutch Slip` < Threshold (clutch locked)

* If Pedal Position input is not configured, Throttle Position is used.

If no disarming condition is configured, the system disarms immediately (nothing is holding it active).

Active Launch Phases

Static

In the Static phase the car is stationary with the engine is held at the desired launch RPM (this is to be controlled by the engine ECU). The TCM can generate a torque limit and/or Engine Speed Target to be issued to the engine via CAN.

Static Clutch Torque: Typically the clutch is either fully open or a small amount of torque is applied for the engine to load up against.

Caution

Applying clutch torque during static phase will lead to very high clutch temperatures and should be treated with caution.

Preload (optional)

Enabled when Preload Stage = ON in Launch Control Setup.

Preload is a dwell phase between Static and Moving where the clutch can be held at a preload torque target for a calibrated time, before the final dump.

It can be triggered in three ways:

Trigger	Enable via	Behaviour
Auto	Preload Stage = ON, Preload User Enable = OFF, Preload Switch = OFF	Entered automatically the instant the arming condition is released.
Preload Switch	Preload Switch = ON	Entered as soon as `Launch Preload Switch` = ON. Can be requested before the arming condition is released, to preload ahead of the Moving phase.
Preload User Enable	Preload User Enable ≠ OFF	Entered as soon as `User Function # Status` = ON. Can be requested before the arming condition is released, to preload ahead of the Moving phase.

Preload → Moving

Preload will exit to Moving when Launch Control Preload Time table value expires, or Max Preload Time expires.
If Preload was entered manually (User Function or Preload Switch) rather than automatically, releasing the arming condition while still in Preload will cut it short and transition immediately to Moving.

Preload Clutch Torque: Typically, a small amount of torque is applied for the engine to load up against. The clutch torque rate is relatively slow so the engine doesn’t suddenly get dragged down.

Example:

The driver arms launch with the Launch Switch and enters Static.
A generous but not excessive time is entered into the Preload Time table (and Max Preload Time).
Moments before launching the Preload Switch is pressed and the system enters Preload.
Clutch pressure is ramped up & engine torque increases.
Before the Launch Preload Time expires, the Launch Switch is released at the exact moment the driver wishes to launch.
The system then enters the Moving phase and ramps the clutch up to full lock torque.

In this scenario, the clutch can be loaded before launching, clutch temperature is minimised, and the driver is still in full control of the moment of launch.

Moving

During the moving phase, clutch torque is ramped up to full lock torque at a controlled rate.

Moving Clutch Torque: The final clutch torque should result in the clutch being fully locked. In a properly modelled system, the clutch will lock when it’s applied torque meets or exceeds the Input Shaft Torque. In a multi-clutch transmission with gear clutch load factors other than 1.0, this may vary and should be considered.

Moving Clutch Torque Rate: Clutch torque should be ramped in fast enough to minimise slip and engine flaring, while not dragging the engine speed down.

Tip

Most of the fine tuning time will be spent dialing in a suitable Moving Clutch Torque Rate.

Per-Phase Calibration Tables

Each of Static / Preload / Moving phases has its own set of tables. Torque Limits are enabled per-phase.

Output	Enable via (per phase)	Table(s)
Engine Speed Target	Engine Speed Target Tables = ON (applies to all 3 phases)	`Static/Preload/Moving Engine Speed Target`
Engine Torque Limit	Static/Preload/Moving Torque Limit = ON	`Static/Preload/Moving Torque Limit`
Clutch Torque	Clutch Control = ON (applies to all 3 phases)	`Static/Preload/Moving Clutch Torque`
Clutch Torque Rate	Clutch Control = ON (applies to all 3 phases)	`Static/Preload/Moving Clutch Torque Rate`

Runtime Channels

The following runtime channels are generated by the Launch control system:

Launch Control Status
Launch Control Engine Speed Target
Launch Control Torque Limit
Launch Control Clutch Torque
Launch Control Static Time
Launch Control Preload Time
Launch Control Moving Time

Interaction with Other Systems

Caution

Care should be taken to ensure other system lockouts are configured, in particular: Takeup.

Transbrake: Transbrake clutches are unconditionally part of the active clutch set while held; Launch Control can overlay pressure on them like any other active clutch but never adds to the set itself.
Takeup: If Takeup’s own Launch Control Lockout option is set, Takeup control locks itself out whenever Launch Control is active (Static/Preload/Moving), so the two won’t fight over clutch pressure.
Clutch-By-Wire (CBW): An active CBW request blocks Launch Control from ever reaching Static (see lockout table above).