ABS shut off switch?

19066 Views 20 Replies 12 Participants Last post by kirtydandra, Aug 8, 2013

kirtydandra

Discussion Starter · Aug 22, 2012 (Edited)

I've recently had the thought of using a normally closed relay and putting it inline with the ABS pump power.

idea being that when the relay is energized it will disable the ABS system making for better braking in muddy/slippery type conditions when I'm out on the trail.

my hypothesis is that the ABS light will come on to let me know it has been deactivated and will turn back off after i turn the switch off (maybe after a key cycle?) to let me know the system is functioning as i do love it for street driving.

has anyone else thought of this? better yet anyone done this? am i missing anything as to why this may be a bad idea? reason for this is i ran into a situation last winter where ABS hurt me more than helped. would like to have this cured by this winter so i can feel a bit more comfortable about it.

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Saint J VT

· #2 · Aug 22, 2012

I think that is an excellent idea. I don't think it would be very difficult to figure out as the ABS unit under my hood, on the passenger side, just inboard and forward of the right-front strut tower should be easy enough to tap into.

I suppose a simple disconnect of any wires leading to that unit may give you an illustration of what you could expect with the added switch! If you have a greasy enough place to slam on the brakes, that would be a good test for the unplugged wire(s)!:29:

CNY_Dave

· #3 · Aug 22, 2012

The only downside is a bit of a reach, but IF you were in an accident and IF they thought for some reason your ABS didn't work and IF they found the altered ABS wiring your insurance company could possibly screw you good by claiming the ABS didn't work and the lack of ABS caused the accident- even if it actually did work.

A truly paranoid person would not put in a switch but would swap the ABS fuse out with a burned-out fuse, but I don't think things are to that point... yet.

I have a few hills near me that when the snow is greasy if I want to stop (no matter how slow I am going down them) there is only one way- kill the key.

kirtydandra

Discussion Starter · #4 · Aug 22, 2012

Yes an easy and cheap mod indeed.

I didn't think of the insurance issue. I realistically think the only time it would be scrutinized that hard is if there was a fatality in said accident?

Maybe I'll get sneaky and hide everything nicely.

But I believe whether abs or not here in WA you'd just get a "unable to control your vehicle" or a "following to closely" ticket.

I am definitely going to be doing this mod in the near future and will post on this thread with pics and final results, costs, etc.

jp1203

· #5 · Aug 22, 2012

That's a neat idea. There are a few situations where I wish I could disable ABS (I've got one of those slick hills that Dave describes around here--even going 10 MPH it's still terrifying when ABS kicks on because there's no way I'll stop when that happens!).

It should be easy to do. I don't think the ABS would come back on until you cycle the key, though. I had my ABS light come on twice last winter because I think I got enough snow and ice on a wheel sensor to mess with it (a guess, but it hasn't come on since). As soon as I pulled over and cycled the key (both times), it went out and the ABS worked again. That would be very easy to test, just by pulling the fuse and putting it back in while the vehicle is running.

kirtydandra

Discussion Starter · #6 · Aug 24, 2012

so with the engine running i pulled the #18 10A fuse on the inside panel. owners manual labels it as the ABS Control/Cruise Control fuse.

the result being with the fuse pulled the ABS light on dash was illuminated. reinstalled the fuse and the light goes out!!!

no key cycle necessary!

so now i just need to figure what wire at the pump to tap into for the same result and ill have "on-the-fly" ABS control which is exactly as i hoped for.

Pdsr

· #7 · Aug 26, 2012

I know that abs failures that trigger the light may also trigger a limp in mode activation in some vehicles. Don't know about Subarus. Had a speed sensor failure on my Mountaineer that caused this.

kirtydandra

Discussion Starter · #8 · Sep 1, 2012

That's because the tranny lost output speed. Different scenario that affected multiple systems. I suppose that could happen too. But since I'll be tapping into pump power or ABS module power it will only set a localized DTC for ABS only and shouldn't affect any other systems. Very good thought though!

Jake2c

· #9 · Sep 1, 2012

I'm not to up on the electric parking break but with a manual parking break in my MB I just engage it and that locks the back wheels. Was never sure what the fronts were doing but I would guess that ABS is still operating and maintaining some sort of steerage. Not sure how this would work for you. The parking break is a very useful tool and going to this electric one is the only thing on the OB and many new cars I don't care for. Could be I just need to get used to it but for the life of me I don't know why you would pull out a purely mechanical emergency break. Anyway just a thought, I don't live where snow is that much of an issue.

Novablue

· #10 · Sep 2, 2012

Jake2c said:
I'm not to up on the electric parking break but with a manual parking break in my MB I just engage it and that locks the back wheels. Was never sure what the fronts were doing but I would guess that ABS is still operating and maintaining some sort of steerage. Not sure how this would work for you. The parking break is a very useful tool and going to this electric one is the only thing on the OB and many new cars I don't care for. Could be I just need to get used to it but for the life of me I don't know why you would pull out a purely mechanical emergency break. Anyway just a thought, I don't live where snow is that much of an issue.

My power ebrake functioned like abs when i did a panic stop with it at 25mph. Well sort of, they locked up... Then released... Locked up... Released... Till the car stopped.

Wish I had a manual one.

Reactions: 1

kirtydandra

Discussion Starter · #11 · Sep 2, 2012

My park brake is the drum hat style where there are rear drum shoes inside the rotor.
That being said they are not designed to be used for a panic or everyday braking as the shoes under that stress tend to break.
Not sure if your newer OBs have the ratchet style calipers but I definitely wouldn't use the e brake for trying to stop in a slippery situation. Unles it was the most
Absolute last resort.

Novablue

· #12 · Sep 6, 2012

kirtydandra said:
My park brake is the drum hat style where there are rear drum shoes inside the rotor.
That being said they are not designed to be used for a panic or everyday braking as the shoes under that stress tend to break.
Not sure if your newer OBs have the ratchet style calipers but I definitely wouldn't use the e brake for trying to stop in a slippery situation. Unles it was the most
Absolute last resort.

I agree. The new ebrake should only really be used this way in true emergency situations. I however believe in testing equipment in non-emergency situations first. The last thing you want to do in an emergency is find out how something works.

twagoon

· #13 · Nov 27, 2012

You wont have to worry about any limp mode in that mod. I used to remove the ABS fuse on my 98 2.5RS and my 96 lifted Legacy sedan for rally-x events. I never had any problem and I definitely had full power.
You could also put a pig tail in there to relocate the fuse and have the switch in line so all wiring is under the dash. That way you don't have to figure out what wire does what at the pump. Just a thought.
Good luck.

ChrisInVT

· #14 · Dec 11, 2012

I wanted to replace the ABS fuse in my car with a burned one, I hate ABS. Only problem is, I love my CC!

kirtydandra

Discussion Starter · #15 · Dec 12, 2012

ha yes which is why a switch whilst off road would be perfect! i dont tend to use CC when bouncing down a rocky hill. haha

outbackpacker3

· #16 · Jan 3, 2013

Has anyone finished this yet? Sounds like it would be a pretty cool mod.

kirtydandra

Discussion Starter · #17 · Jan 4, 2013

no not yet. ha. i want to so badly but the place i want to put the switch requires me to get an aftermarket single din stereo.

i had plans to make a plate to fill the space below the stereo and put 2 mini gauges (oil and volts) on either side and the switch right in the middle. perhaps ill find a temp location i can lay the switch for now just so this thread can be finished off. ill post pics of where i put the relay, what wire i split, etc.

AWDfreak

· #18 · Jan 31, 2013

Any progress pictures?

Also, was wondering if anyone did a VDC full-shutoff switch as well (since it seems only the WRX STI is the only Subaru that can COMPLETELY disable VDC)?

CNY_Dave

· #19 · Jan 31, 2013

VDC shutoff as in disabling the ability of the VDC to apply the brakes?

Reactions: 1

curry.style

· #20 · Jul 16, 2013

There is a writeup for this on dirtyimpreza. Just an FYI.

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