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.
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!?