Ah I see !

The ABS module checks the sensor for operating a parameters continuously and splicing may load the signal either permanenty or erratiaclly causing issues with normal operation.

The best way is to build an interface using electronics ....
An operational differential amplifier with high impedance input and current limited inputs is needed to isolate the systems.
(sorry if its over your head)

Another issue is that ther ABS system pulses will be very fast even at a moderate road speed and there may be issues with the dash accepting such a high speed signal but I am no expert on the dash mentioned.
If this is the case, the signal may need digital dividing to reduce this rate.

I would contact your dash makers as they may have an off the shelf solution.