88 k100 harness and electronics questions

[Hud]

Received a used cdi fuel injection harness from ebay seller...harness that arrived has a white 5 pin connector and 3 ground wires to efi plug..mine has a black 4 pin and 2 ground wires...did I get an ABS harness?...can I cut one wire and splice in my 4 pin?? ..Also the big plug to the brain box plug has one more female pin than my original...thanks for any info.

[frankenduck]

Does the FI wiring harness have an "extra" connector with violet/gray and brown wires?

The early K100s (built up to 4/85) had a vacuum switch on the TBs that connected to ICU Pin 15 so my guess would be that you have an early FI harness. K100s built after 4/85 don't have that switch.

The switch is part 10 here:
https://www.realoem.com/bmw/enUS/showparts?id=0513-USA---K589-BMW-K%20100%20RS%2083%20(0502,0503,0513)&diagId=13_0515

The early FI harness with the "extra" switch connecter is 61111459520. The later one is 61111459591.
https://www.realoem.com/bmw/enUS/showparts?id=0513-USA---K589-BMW-K%20100%20RS%2083%20(0502,0503,0513)&diagId=61_2724

The main wiring harness is different as well:
https://www.realoem.com/bmw/enUS/showparts?id=0513-USA---K589-BMW-K%20100%20RS%2083%20(0502,0503,0513)&diagId=61_2725

I'd guess that what you need is the later FI harness.

ABS has nothing to do with the fuel system.

[Hud]

Thanks for that response..most appreciated..there was a confusion on the year on this bike..it turns out to be 1987 and the fi harness I received was for an 84..so that would explain the extra wires..I have ordered the correct harness..thanks again.