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ABS2 Modulator Repair


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If you've heard it, you know it - that bad feeling when suddenly your bike is making a new sound that you know isn't right. I heard it, instead of that "whoosh-snick" at first roll off, there was a loud "ker-klunk". Very soon after that the ABS lights were wig-waggin and wouldn't self reset at startup. Investigation of the ABS Fault code and confirmed at the dealer - the ABS Hydro Modulator unit was giving a piston fault and would need replacement. When the dealer had it on their computer they also ran a piston pressure test on the ABS. This pushed the ABS pistons up and down and cleared the fault - for a day or so, but it was still loud at self-test and faulted again the next day.


New part is $2,200 plus labor to install. I searched and found a claimed good ABS unit on e-bay and bought it for $300. I also did more online searching and found a good write up at the ADV Rider Hall of Wisdom for disassembly and analysis of an ABS-2 modulator.



With that as a guide I opened up the hydraulic pistons on the ABS2. Found a little crud in the bleeder area, cleaned everything and reassembled. Pumped through fresh brake fluid and had firm brakes, but the fault still showed up after I forced a reset and the unit self test was still really loud.


So, one last try before I gave up and had the unit swapped out. I went back to the dealer and paid for the computer time and had them run the piston pressure test three times. The first time it was pretty noisy, but the second one the noise of the piston cycling through its travel was not that bad. Result, so far, is the ABS is self testing quietly just like it did in the past. It's only been 3 days with mutiple restarts and self tests and they all sound good.


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Danny caddyshack Noonan


glad you got it up and running.

I found some rubber like material in my controller to rear caliper hard line that seems to have solved my problem. Found it when the rear flexi-hose failed.

If you have more problems, you might consider pulling the abs bleeder caps and reverse flush with shop air from the calipers.

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You need a 22mm deep socket to take off the large fittings below the bleeders. The socket has to be thinned in order to fit into the well where they sit. The rubber O ring that fits on the large fitting will probably be sitting in the unit when you take the fitting out. The bushing has to be snagged and pulled out with a tiny screwdriver or pick and then the piston itself is pulled straight up by grabbing the tip with a needle nose plier.


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