Disabling ABS on an E46 xi [updated]

by "functionoverfashion" (functionoverfashion)
Published 01/05/2017 at 09:55

Tags: rally car
STARS: 0

I’m going to an open course session at Team O’Neil next weekend, and I want to be able to drive my car like a proper rally car, including liberal use of the left foot braking technique. I am comfortable with this technique, and I wish to apply it as appropriate on the course. The problem is, ABS really gets in the way of this on loose surfaces, which IS the surface at O’Neil’s.

So I asked over on a BMW forum but haven’t found any specific answers yet. Of COURSE I searched the interwebz first, but again, the information out there is a bit confusing and contradictory at times. I’m posting the exact information I did at bimmerfest here in case someone has any experience with this.

I have to throw in my disclaimer which is, if you’re going to tell me not to do this, just keep it to yourself please. I understand the risks, and I’m only doing this on a closed course for part of one day and then immediately reversing the change and putting my car back to normal.

!!! UNKNOWN CONTENT TYPE !!!

My car is a 2003 325xi wagon, 5 speed manual. I can (and will) disable DSC by pressing my little button on the center stack. That’s easy. It’s the ABS that’s tricky.

I’ve read that I could disconnect the main harness to the ABS module under the hood - this is the unit that I believe also runs the DSC, which is fine because I don’t want that either. I get that there will be warning lights, but will this also cause limp mode problems?

I don’t believe pulling a fuse will work, there are 4 associated with DSC and ABS and I’m sure they do other stuff too.

In my ‘96 Accord I could pull a single relay under the hood. I’ve not seen any such option for this car, but maybe? My Bentley manual is a bit inconclusive, as I got mine when I had an ‘01 and there are some variations.

Lastly, I found some who said you could disconnect just one wheel speed sensor, which trips a warning light but disables ABS and does NOT cause limp mode since it’s only one wheel . Any confirmation of this in a 3-series xi? This is not ideal because I’d have to lift the car and/or take off a wheel to reach the connector. But if it’s the only way, maybe. They might let me put my car on a lift for 1 minute and reach up to disconnect the harness.

Any ideas or experience with this would be appreciated.

Update: In an effort to try the easiest things first, I actually had a chance to drive on a completely blue-ice road at lunch time (another story), so I started pulling fuses. I mistakenly said there were 4 ABS related fuses, there are actually 5, and I had to pull FOUR of them before the system stopped working. I put 3 of the 4 back, and it stayed the same (disabled) so I guess I found the answer. FUSE #53! It’s a big one, 30 amp. That’s telling. But I had pulled another 30a fuse already, with no noticeable effect. But Fuse 53 came out and I got the DSC, BRAKE and ABS lights all on the dash; ABS and DSC are completely disabled as far as I could tell. More (ahem) testing (ahem) is required to be sure. And the car drove normally otherwise. Yay!?

Replies (24)

"Party-vi" (party-vi)
01/05/2017 at 09:58, STARS: 0

Just fuck up your steering position sensor - it’ll throw your ABS and DSC light on.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:04, STARS: 0

I assume you mean, “disconnect?” Where is that puppy located, and can I get to it without a lot of trouble?

"Trunk Impaired 318" (matteocscaptura)
01/05/2017 at 10:07, STARS: 0

Disconnecting a wheel speed sensor should do it, you also might be able to just pull a fuse

"awmaster10" (awmaster10)
01/05/2017 at 10:08, STARS: 1

id say one wheel speed sensor sounds the most plausible.

"Party-vi" (party-vi)
01/05/2017 at 10:08, STARS: 2

You cannot get to it without a lot of trouble - I was mostly joking.

Here you go . Pull one rear wheel speed sensor to disable ABS and DSC.

"kanadanmajava1" (kanadanmajava1)
01/05/2017 at 10:24, STARS: 0

You might try to get into “dyno mode”. It should disable all traction control related things and maybe the ABS too. It can be done in most E46s by doing certain things with the DSC button.

In most cases all that is requires is holding the DSC button for long (20-30 seconds) but some models (M3 is very tricky) require different things. Try googling if it doesn’t work just with the button.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:33, STARS: 0

Hmm, yeah I’m leaning that way I guess. I found that link via google but it’s not an xi, I don’t believe. Unless someone is drifting an xi.

My issue is I don’t want to have to get under the car, or get a wheel off, if I don’t have to... I might be able to reach a front sensor by putting the steering full-lock to one side. That I could try at lunch time today!

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:34, STARS: 0

I’ve found that pressing the DSC button for 30 seconds only makes the light come on, then go off, leaving DSC enabled until I restart the car. Even pressing the button again after that doesn’t turn it off, which it normally does. And ABS is unaffected!

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:36, STARS: 0

There are 4 fuses associated, but you know, I could try them one at a time - that doesn’t even require getting out of the car! I am sort of hoping someone will say, “oh yeah I do this on track days, just pull fuse #XX and you won’t be able to adjust your mirrors (or something non-essential) but ABS is disabled...” that’s my dream.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:37, STARS: 1

I’m just hoping I can pull a front one, because I don’t want to have to get under the car. I might be able to reach a front one with the wheel turned full-lock?

"Trunk Impaired 318" (matteocscaptura)
01/05/2017 at 10:43, STARS: 0

On my E36/5 that I autocross its just 1 fuse that needs to be pulled and typically BMW doesn’t change a lot of stuff like that very often.

"GUYMANDUDE" (guymandudebro)
01/05/2017 at 10:47, STARS: 0

You can pull all the fuses for abs and ASC, it will disable both. Unplugging the harness at the ABS pump might be the easiest. There should be a relay with ABS marked on the top you can pull ( not sure about e46).

Unplugging all the ABS and ASC fuses worked on my 97 e36 328i. I’m sure unplugging the ABS harness from the pump will work. Both are easier than jacking up the car and pulling a wheel just to unplug a sensor.

"GUYMANDUDE" (guymandudebro)
01/05/2017 at 10:50, STARS: 0

Pull the fuses, there won’t be anything else on that fuse other than ABS and ASC.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:53, STARS: 0

pic from e46 fanatics. So, I’ve got 5 choices...

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:55, STARS: 0

Actually, you’re mostly right - if you look at the diagram, heated seats are the only thing I can find at a quick glance. I think I will manage. Now to try this...

"Trunk Impaired 318" (matteocscaptura)
01/05/2017 at 10:57, STARS: 0

I believe I do the equivalent of 12 which also has the heated seats. 33 looks like it would be a good choice as well, but any one of them should work.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 10:57, STARS: 1

Awesome. It sounds like I’ve just gotta try a couple of these things... pulling fuses, I can probably make the time for that.

But you’d be amazed, with 2 kids under 4 at home, how even 5 free minutes in the day time can be challenging.

"functionoverfashion" (functionoverfashion)
01/05/2017 at 11:01, STARS: 0

What’s funny is I was going to use the heated seats as an example of something you don’t need on a rally course. But I went with mirror adjustment, haha. If I can pull just one, that’s ideal. So long as I can avoid the dreaded Limp Mode. No one wants to be limp.

"Trunk Impaired 318" (matteocscaptura)
01/05/2017 at 11:08, STARS: 1

I would try a fuse first, should be pretty easy and unlikely to trip limp mode.

"kanadanmajava1" (kanadanmajava1)
01/05/2017 at 11:11, STARS: 0

Maybe the “X” causes that normal tricks do not work? At work we have only a single roller dyno so we don’t usually touch any awd cars.

In early M3s you had to push the DSC button for 8-10 seconds while the ignition was on. Then you need to hold down “sport” button while starting the engine. Hard to say if it works with other models.

According to some source the dyno mode turns off after the ignition has been off for 5 minutes. So if you get the car into some weird mode, you probably have to wait for a while before trying again.

"Party-vi" (party-vi)
01/05/2017 at 12:13, STARS: 0

I think one of the front sensors will put you into limp mode, but that’s easy enough to figure out once you have it disconnected.

"awmaster10" (awmaster10)
01/05/2017 at 17:56, STARS: 0

Yeah youd have to check a blown up diagram of the front and try to find out where to access it from, i have no clue

"functionoverfashion" (functionoverfashion)
01/05/2017 at 21:25, STARS: 1

It’s easy once the wheel is off.... just don’t want to take a wheel off if I don’t have to.

"e36Jeff now drives a ZHP" (e36jeff)
01/14/2017 at 23:11, STARS: 1

Dunno if there is a way to kill ABS and not DSC, but if you do a long press(10-15 sec or longer) it disables the engine management part of traction control but retains the fake LSD part which controls the brakes to make the open diff act as an LSD.