I recently had a local guy contact me about his inability to brake torque launch his automatic 2013 G37 convertible coupe. He asked me if I could "fix" the car so that when he applied the brakes while the car was at stand still he could rev the motor. I agreed to take a look at the car and I was surprised when the "old tricks" of cutting the yaw sensor power and the brake signal to the ECU failed to allow the car to brake torque.

Well, today he brought the car back and agreed to leave it for the day. I was able to find a way to allow brake torquing! I was quite surprised how aggressive the car is when it doesn't "think" the brake is being applied!

I installed a KPtechnologies Traction Control Memory switch as the foundation of the mod. This module has an AUX output that can be triggered by pressing the VDC Off button twice quickly. I wired the 200mA AUX output to a 30A SPDT relay and then used that relay to trigger two separate 30A SPDT relays. The first relay cut power to the Yaw sensor in the center console which causes the VDC system to fault out and not intervene with driving in any way. The second relay cuts a pink wire at the fuse box in the drivers kick panel. This pink wire comes from the brake switch and to the ECU, and to another controller (not sure which one). You HAVE to cut the wire in the drivers kick - doing it at the ECU will NOT work.

Now, when he stars the car if he wants "competitive" mode he simply hits the VDC button twice quickly. The VDC faults out and the brake signal that is used to prevent accelerating while braking is eliminated. The brake lights still work! The car stays in this state until the ignition is turned off.

Instead of using the $39 module from KPtechnologies you could easily add a SPST or SPDT switch to the wire. The one important thing to remember is that the car will NOT start if the wire is cut (as the car won't think the brake is being pushed in). Therefore, the switch would have to be off every time you start the car.

I took a quick picture of the wire I cut:


It is a pink wire in the center plug. I did remove the drivers sill plate and the plastic kick panel piece to make it easier to get to this wiring. Once cut I soldered a black and red twisted wire to two pink wires and ran the twisted wire to my relay that was tucked away behind the fuse box.

Once everything was done and put back together the customer was ecstatic. He has some mild NA mods (Stillen intake, Stillen exhaust, ECU reflash) and he likes to drag the car but has always had issues getting a good launch. Well, he can no longer blame the car!

 

You have all your customers sign claim release documents before doing these mods, right?

 

I've never had a customer sign anything.

 

Link to said module?

 

@KPierson_, if such a vehicle was to be involved in some sort of crash where it was determined that tampering with a safety device was the cause, coverage could be denied.

 

It was installed for "off road use". In this case, I actually believe that this customer will only use it at the track.

 

Can I get a link to this device? or can it be done without it?

 

^^^ Must be different from the 2008 series, if the brake switch doesn't work.

I have a simpler toggle which I split to one of the two wires leading to the brake switch and it works famously. Like you allowed, if it stalls, you HAVE to switch it on to restart.

I don't do this on the road, so the loss of brake lights is irrelevant for me. For him, too?

Thanks for the concise write up.

 

This is his website. He's been around doing this type of stiff for years.


KP Technologies

 

I did find that it would work if I completely disconnected the brake switch. However, like you said that killed the brake lights. Even in an "off road" use situation I was not comfortable with that solution. I don't remember previous years having such a low rev limited when the brake is applied though - on this 2013 if the car was standing still and the brake was applied it would not rev past 1900 RPM.

 

Hi Kevin,

Got it. You can see mine at play in my vid in my sig line. In one of my previous vids (3 x 11.7's) I stall it, and recover with some quick toggling.

Aside: SO wishing your talents would stray into the 5AT and 7AT automatic's computer and programming. This is an area which is in dire need of improvements.

Thank you.

Jim

 

I have done the same method as Cooper did and it works well for me. Mine is 2008 as well. ( Thanks for the tip Cooper)

 

I am doing this tomorrow. Will let you know how it turns out! lol

 

So I made a switch to cut the power to the YAW sensor and a switch for the break.

Both done, both turned on and it still does not work.

Any more ideas? Or is there something I missed?

 

How did you do it? Two separate switches?

When you cut power to the yaw sensor you should get a light on the dash.

When you cut power to the brake you won't get any indications that anything has changed.

Where did you cut the brake wire? Did you verify it was the correct wire with a volt meter before cutting it?