You sure you are using the correct cable AND that there is not a problem with the cable?
I have seen many of the GPS cables/socket break part of the center divider and it can get stuck inside the end of the cable and it will not fully seat if there is something stuck inside the center the cable.
We are taking about the small connector that is plastic on one side and metal on the other, not a full metal connector head shell.
You could Google "Uniden BWZG1844001" which is the part number for the Home Patrol, x96T,/x99XT GPS cable. Some pictures of this cable should be seen and you could tell if the end appears to fit in the 436.
The Home Patrol manual mentions this part number. The 436 manual isn't as specific, it just says ". . . use the 4 pin mini plug to connect".
A suggestion to Upman when he reads this: If this part number is correct, could you think about updating the 436_536 manual to include the part number as you did with the Home Patrol?