2000 GMC Safari knock sensor

Hi and thank you for your time.
I have a 2000 GMC safari van and need to know which two wires come from the computer to the knock sensor? To fill you in a little I had the motor replaced and the mechanic didn't unhook the knock sensor, which broke the line somewhere in the harness. It's my understanding that the two line to the knock sensor go directly to the computer and can be spliced in so that the sensor works but can't seem to find out which two lines they are. I don't want to chance pulling the wire harness apart knowing that the wire coating will be frail and degraded which can cause even more problems.
The van and motor are both 2000 GMC.
The van runs fine unless I drive it at highway speeds then it knocks and backfires.
At this time I have one wire to the original wire and one wire grounded.
Codes tell me to replace knock sensor. No other problems.