UABYJ94s description is what you need.
I would add:
1. If you are already there - check the wire clusters for breaks, tears, wear, might save you some hunting for electrical shorts later.
2. Be careful when putting the wire clusters back, so not to put them in a place where they will rub against something and cause electrical shorts.
3. You might want to disconnect your negative battery wire when messing with plugs, clusters, etc. (of course put it back on when checking if it works