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Old 09-02-2010, 02:51 AM   #22
Romanian Trailbiker
switch's Avatar
Joined: May 2009
Location: Eastern Europe
Oddometer: 678
Allright, I've done about a hundred miles with my the modded ABS and I dare say it worked flawlessly.

Here's what I did (on a BMW R1100GS, prod yr 1997):
1. Remove seats, fairing (GS only has like one piece) and fuel tank
Tip: If you have a tall chair available, put it on the right side of the bike, next to the rider footpeg. You can rest the tank on the chair to avoid having to disconnect the fuel lines. Be extra careful in securing the tank!
2. Disconnect battery terminals -- for the sake of the bike's electronics

3. Locate and disconnect the ABS connector: it's a large connector going into the the left side of the ABS unit just in front of the battery
TIP: the connector is held in place by a latch on the bottom end. A flat screwdriver can be used to release the connector's bottom clamp. Hard to explain, even I don't get it after doing it twice. Bottom line is that you don't need to undo anything else, just push the clamp out of the way and unplug the bottom end of the connector. Top end just wiggles out.

4. Locate and pull out the wiring harness splice point #15: it's behind the alternator, left side.
TIP: The splice point is likely hidden behind the rest of the harness when you look at the bike from the left side. Here's some pics, courtesy of a guy that did a similar mod on his R1100:

5. Remove the insulation and find the large bundle of 9 green wires. Cut the crimping and isolate each of the wires

6. Locate pin #15 on the ABS connector
TIP: When looking at the abs connector pins with the wires coming out the bottom, pin #15 is on the right row, second pin from the bottom up

7. Determine which of the 9 wires from the bundle connects to pin #15 on the ABS connector
TIP: Only one of the 9 green wires in the bundle connects to pin #15. It's one of the THIN wires. MARK IT.

TIP: After identifying the wire, mark it (did you mark it yet?) and reconnect the ABS connector -- you're done with it.
8. Bundle the 8 wires not connected to pin #15 and solder them back together. Take extra care to make sure they are ALL soldered together properly.

9. Solder the wire going to pin 15 to your 5-inch piece of wire; isolate all solder points, check integrity then run your wire out of the bundle and tape the bundle back together
TIP: Don't push the bundle back in yet!

TIP: In the picture, the wire is brown (indicated by the RED arrow), despite the fact that it's not a BMW standard ground wire.

TIP: The BLUE arrow indicated the wire coming from the alternator's D+ connector.

10. On the rear-left side of the alternator, locate and remove the D+ connector with the BLUE wire
TIP: In the picture above, the blue wire is indicated by the BLUE arrow.

11. Splice into the blue wire and solder the other end of the 5 inch wire you connected into the bundle (step 9). Carefully isolate everything after soldering.
TIP: At this point, the electrical diagram for the ABS has been modified to:

12. Test everything (you DID re-connect the ABS connector and alternator D+ terminal, right?). If it appears ok, isolate everything nice and tight, and reassemble the bike. Prepare for a test-ride.
TIP: The ABS lights will behave differently during startup! This is expected and suggests you did things right.

That's it. Test ride and slam the brakes to check for abs functionality.

Now, during start-up, the ABS lights work differently:
- when you turn the ignition, the top ABS light comes on solid
- during tick-over, I *think* the top ABS light goes out -- didn't pay attention, sorry
- after the engine starts and the battery light goes out, both ABS light blink in unison (indicating the ABS is initialized).

That's the only difference. Note that disabling the ABS requires you to keep the ABS button down until the engine starts AND the battery light goes out.

EDIT (one year later): I've done about 7k miles with this ABS mod. No issues, never had the ABS fault.
No bikes right now :( Used to own the best dommie in Romania and a damn-good R1100GS. Modded the hell out of both before selling them. Looking to get another bike soon.

switch screwed with this post 09-29-2011 at 01:59 AM
switch is offline   Reply With Quote