Toggling ABS On/Off... creative solutions?
Dec 18, 2016, 07:55 AM
#1
Toggling ABS On/Off... creative solutions?
I know this is kind of a ridiculous question. Bear with me...
I'm going to be tracking my Evo, starting in January on gravel and dirt/snow. In these conditions, it seems to me that ABS would be an impairment. But come summertime (or if I do any DD with it), I may prefer to have the ABS active.
Is there any sort of way to engage/disengage this function? From what I understand, the "easy button" would be to pull the fuse, but may impact performance of other functions.
I'd really love to implement a switch in the cabin. But I don't wanna eff stuff up.
I'm going to be tracking my Evo, starting in January on gravel and dirt/snow. In these conditions, it seems to me that ABS would be an impairment. But come summertime (or if I do any DD with it), I may prefer to have the ABS active.
Is there any sort of way to engage/disengage this function? From what I understand, the "easy button" would be to pull the fuse, but may impact performance of other functions.
I'd really love to implement a switch in the cabin. But I don't wanna eff stuff up.
Dec 18, 2016, 09:42 AM
#2
EvoM Guru
iTrader: (1)
Unplug the abs pump
Dec 18, 2016, 05:45 PM
#4
EvoM Guru
iTrader: (1)
Originally Posted by V.8MR
Would probably create an ABS code which in-turn would disable ACD...
Dec 18, 2016, 06:53 PM
#5
I found a post in a Subaru forum about this. Someone addressed the challenge of differentials, which intriguingly was caused by the ABS unit sensing the ABS light being on...
"I finally got around to adding the ABS toggle switch to my car, but I wanted to do it in a better way that doesn't cause any of the problems identified earlier in this thread.
What I did was to basically disconnect the brake light signal from the ABS unit. The ABS unit checks for an open circuit on that wire, so if you just switch the wire, it will trigger a trouble code, so you have to ground the wire when switching the ABS off.
I did this when I had the harness out of the car while swapping engines, so I had no trouble getting to the wires. If your car is not apart, the only easy place to access the wire is right at the ABS unit. On the '93 - '07 cars, it is a white wire with a black stripe. You can verify that you've found the right one by testing with a multimeter: it will have 12V when pressing the brake pedal (even with the car off) and 0V when the brake pedal is not pressed.
When you find the right one, cut it and run both ends of the wire to where you want the switch. Then add the circuit shown below:
https://www.msu.edu/~ushernat/ABSdiagram.jpg
The resistor may be optional, but I suspect if you don't install it you will eventually trigger an ABS code and lose ABS until you clear the code.
With this method, the ABS light in the instrument cluster never comes on, even with ABS disabled. You can also toggle on and off at will without having to restart the car or wait for it to do its self test. I think it will also solve the problems with the STi center differential, but I don't have an STi to test it on. (I also don't have access to an '08+ car so I can't verify what effect it will have on the stability control system. All I do know about them is that the brake light wire is a different color on those cars.)"
"I finally got around to adding the ABS toggle switch to my car, but I wanted to do it in a better way that doesn't cause any of the problems identified earlier in this thread.
What I did was to basically disconnect the brake light signal from the ABS unit. The ABS unit checks for an open circuit on that wire, so if you just switch the wire, it will trigger a trouble code, so you have to ground the wire when switching the ABS off.
I did this when I had the harness out of the car while swapping engines, so I had no trouble getting to the wires. If your car is not apart, the only easy place to access the wire is right at the ABS unit. On the '93 - '07 cars, it is a white wire with a black stripe. You can verify that you've found the right one by testing with a multimeter: it will have 12V when pressing the brake pedal (even with the car off) and 0V when the brake pedal is not pressed.
When you find the right one, cut it and run both ends of the wire to where you want the switch. Then add the circuit shown below:
https://www.msu.edu/~ushernat/ABSdiagram.jpg
The resistor may be optional, but I suspect if you don't install it you will eventually trigger an ABS code and lose ABS until you clear the code.
With this method, the ABS light in the instrument cluster never comes on, even with ABS disabled. You can also toggle on and off at will without having to restart the car or wait for it to do its self test. I think it will also solve the problems with the STi center differential, but I don't have an STi to test it on. (I also don't have access to an '08+ car so I can't verify what effect it will have on the stability control system. All I do know about them is that the brake light wire is a different color on those cars.)"
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