roberga

Pulling out of a gas station at an angle I had a front wheel off the road and the ABS failure light came on. I did not know that all I had to do was turn the car off and it would reset.

I also did not know that when that light is on the brakes are off. Ended up flat spotting the front tires while I slid (straight) to a stop. No rear brake 100% front and the PS2s just could not hang in there.

Leason learned: light come on turn car off. So much for my idea of pulling the fuse for track days.

NJ-GT

I get that at the exit of one local gas station. To prevent it, you have to exit a very slow speed. Another option is to run a full soft front sway.

I pulled out the ABS fuse once, and the outcome was really bad (100% front brakes or something like that).

I also removed the switch on the brake pedal to allow for left foot braking, with better results than ABS fuse removed, but nowhere near to what I wanted.

I just live with the e-gas. The car is so responsive to throttle input with the LFW that left foot braking is not that critical, but I'm leaving a few tenths of a second there.

mds

I discovered an alternative for enabling left foot braking without throttle cutoff: Cut the ESO wire that runs from the ABS unit to the ECU. This hack preserves all ABS functions as well as the rear brake lights.

NJ-GT

Mike, please illustrate me. What's the ESO wire from the ABS unit ? (I don't want to cut the wrong wire).

I really need this.

Thanks

cosmos

But dont ya get the person trapped in trunk light?

mds

The ESO (Emergency Shut Off) is the white/brown wire connected to pin 19 on the ABS unit wire connector. Remove the plastic cover around the brake fluid reservoir to expose the ABS unit. Untape the wire bundle leading to the ABS unit. You will see two white wires each with a single brown stripe. One is twisted together with a second wire. Don't cut that one, it is part of a wheel speed sensor circuit. Cut the straight white/brown wire that is untwisted. Or install an inline switch as I show in the picture below.

Once the ESO is cut you can left foot brake freely with no throttle cutoff. All other braking, ABS and throttle functions continue to work normally. There are no other side effects, except for this:

After a couple of drive cycles, you will get a check engine light and an OBDII code 0501. This code is a notification that the ECU no longer sees an ABS braking signal on the ESO. The check engine light and code will reset automatically when you reconnect the wire. While the CEL is lit, the car runs normally..

In the picture, you can see the switch mounted below the ABS unit. I soldered the exposed white and red switch lead wires onto the cut ends of the ESO wire, so the on/off switch is installed inline to the circuit. The only reason for the switch is so that you can restore normal operation. I do so to avoid confusing the techs when I take the car in for service.

As Cos mentions, the ESO is also connected to the trunk entrapment latch. If someone gets caught in the trunk and releases the latch, the ECU will cut the throttle. The ESO is also connected to the headlights. So some sort of unknown headlight condition can cause the throttle to be cut too.

Dubai911

Guys, all this stuff sounds dangerous!!! I am a wuss and would never cut anything related to brakes, and am not that much of a pro driver that I would even want to.
Is the ABS really hampering your times that bad??

NJ-GT

Mike,

Thanks for such a valuable information. I'm going with the switch idea as well. This disadvantage from e-gas was really hurting my car at the SCCA Solo2 races.

Dubai,

When you're competing in a motorsport where first and second place are commonly thousand or hundred of a second apart, left foot braking is helpful. It's not related to the ABS functionality. On the e-gas Porsches, the gas pedal doesn't work if you're hitting the brakes.

mds

Rhamy,

Most people don't left foot brake and can't imagine why you would want to do it. I find left foot braking helpful for driving smoother on twisty mountain roads. As you move your foot from the throttle to the brake there seems to be a moment of slight unsmoothness in the rate of the car's deacceleration. Left foot braking helps smooth out this transition and improves the car's feedback and balance. The improvement is subtle, but it seems to me that the car responds positively to this technique.

GT2RS

roberga,

I have a friend with an '04 GT3 who had the same situation... except the brakes locked up and skidded into another car thereby causing damage to his car and the car in front of him. Now his insurance company is of course trying to say it was driver error.

Any way to confirm that the rear brakes don't work when the ABS failure light comes on? He visited his local Porsche dealer today, and they are adamantly denying that anything like this is even possible. Called the Porsche engineer, and they are also trying to deny any possibility that this could ever happen.

I think it would really suck for him to get popped for this when it really is a quirk of the car. It's not like the owner's manual warns you about anything like this or even tells you to restart the car.

Any help would be much appreciated.

roberga

My local guy checked with PNA. He said that the rear brakes do apply some force but the fronts are loaded to lock. This is to prevent the rears from locking which would have the rear come around.

I guess the driver error is that we drove it at all with the ABS failure light on. The fix is to turn the car off, wait a few seconds and start it up again.

GT2RS

Hmmm... so does that mean that my friend is SOL? Or should he attempt to talk to the PNA folks? This is obviously not explained in the owner's manual... kinda scary thought if he had been traveling on the freeway at higher speeds.

cbennettus

"I have a friend with an '04 GT3 who had the same situation... except the brakes locked up and skidded into another car thereby causing damage to his car and the car in front of him. Now his insurance company is of course trying to say it was driver error.
"

I can't believe what I'm reading on a GT-3 FORUM none the less. Sounds like there are a select few rely on ABS and ham footed braking to stop the car. On the street ABS is purely backup. If you rear ended another car and your ABS wasn't working - it's because YOU didn't brake properly.

This is CLEARLY driver error. Take out your check book, pay up, and accept the responsibility.

DanH

So in the US, if its driver error on your part, you have to pay? Aren't all accidents somewhat down to driver error?

Chennettus, I think the point they are making is that if the ABS failure light is on, your braking distances massively increase as the cars computer screws with the brake bias.

roberga

DanH... the insurance company will pay regardless. I think his ploy is to try to prevent the raise in his rates from going up.

Cbennettus: The brake bias is completely different with the light on. It is not like the balance and stop distance are the same just without the ABS. The way it was explained to me is that the same computer that controlls the ABS controls other aspects of the brakes. When the light comes on the distance increases a lot and the front all designed to lock to prevent the rears from doing the same.