What this node sets up
The Trans-Brake Wiring page in NSP decides how the ECU interacts with your trans-brake: whether it just watches the button, or actually drives the solenoid too. It's also where you add a bump box function for staging. Get this right before tuning anything in the trans-brake function itself.
Choosing the modes
| Setting | Option | When to use it |
|---|---|---|
| Trans-Brake Control | Not Used | No trans-brake, or you don't want the ECU involved |
| Input Only | The ECU reads the button (for launch strategies and logging) but something else powers the solenoid | |
| Input and Output | The ECU reads the button and switches the solenoid itself | |
| Bump Box Function | Not Used | No bump or creep needed |
| Bump | Short pulses to nudge the car forward into the beams | |
| Creep | Controlled, continuous movement while staging |
You can run bump or creep, not both at once. The pulse behavior is tuned on the bump/creep duty cycle page.
Inputs
Both the Trans-Brake Input (the driver's button) and the Bump/Creep Input should go to an AVI (analog voltage input) or an SPI (synchronized pulsed input). Pick whichever you have spare, and log the input while you press the button to confirm it switches cleanly.
Outputs: this is where people get it wrong
The Trans-Brake Output and Bump/Creep Output drive the transmission's solenoid, and that solenoid draws a lot of current. That means:
- Use a high current output (HCO) wherever you can, ideally a 25 A HCO.
- No HCO free? Use a digital pulsed output (DPO) to switch a relay, and let the relay carry the solenoid current. For bump or creep, that relay needs to be solid state, because a mechanical relay can't keep up with rapid pulsing and will wear out fast. The 100 A solid state relay is a good fit.
- Set Soft Start Duration to 0 on these outputs. You want the solenoid to snap on and off, not ramp.
Wiring a trans-brake solenoid straight to a low-current output isn't a shortcut. It risks damaging the ECU output and gives you an unreliable brake right when you're staged. If you're unsure about relays, read how relays work and why you need one.
Before you hit the lanes
- With the engine off, press the button and confirm the input changes state in NSP.
- Check that the solenoid clicks in and releases instantly when the button is released.
- Test bump or creep at low RPM in a safe area before using it on the line.
Trans-brake setups often go hand in hand with launch control and flat shift. If you'd like a hand planning the wiring for a drag build, book a free consultation.
