Wiper System Question

[66 Valiant]

My 66 Dart owner’s manual says I have a variable speed wiper set up.
The variable speed wiper switch has been tested it as per manual and is working.
The wiper motor is a two wire signal speed. I’m guessing it was replaced at some time. Note: There are the four wires on the wiring harness for a variable speed wiper motor.
I found a variable speed wiper motor (four wire) Tested as per manual and it is working. I installed it and only one speed works.
I did a continuity check of the wires from the switch to the motor and all are ok.
I’m thinking the ground on Motor and the live wire from the ignition switch must be working because the wiper motor is rotating just not at variable speeds.
I’m stumped!
Something I find really odd on the wiring diagram in the manual is that one wire goes from the wiper switch to the backup light switch. I can’t think what these to electrical circuits have in common.
Any suggestion as to why the variable speed is not working?

 

[67Dart273]

I have yet to run this down. It appears that it must be a hot feed. With key on, do the reverse lights work? this wire (appears to be B-1 violet-tr) should be hot with key on I would think.

It appears to me that the hot feed source may have been left off the diagram

 

[66 Valiant]

OK I figured it out! I’m happy to have the variable wiper system working finally. It's been a challenge getting this working. First variable speed wiper motor I got only worked on one speed. The second motor on the bench test worked but not when I installed it. And like every other electrical snag I’ve had on this car it’s been a GROUND!! The grounding strap on the motor wasn’t tight or cleaned. Then I kept on testing with the dash out and the wiper switch dangling there. It still didn’t work until I touched the switch to the dash frame. OK, from now on I’m checking my grounds first for all other electrical problems. It would have saved me a lot of time and headaches if I did this first; on the up side I learned a lot about the wiring under the dash I’m sure will come in handy later. I haven't tracked down the B1 Violet wire but I finally got the wipers working. I'll check if my reverse lights are working later.

 

[RedFish]

OK I figured it out! I’m happy to have the variable wiper system working finally. It's been a challenge getting this working. First variable speed wiper motor I got only worked on one speed. The second motor on the bench test worked but not when I installed it. And like every other electrical snag I’ve had on this car it’s been a GROUND!! The grounding strap on the motor wasn’t tight or cleaned. Then I kept on testing with the dash out and the wiper switch dangling there. It still didn’t work until I touched the switch to the dash frame. OK, from now on I’m checking my grounds first for all other electrical problems. It would have saved me a lot of time and headaches if I did this first; on the up side I learned a lot about the wiring under the dash I’m sure will come in handy later. I haven't tracked down the B1 Violet wire but I finally got the wipers working. I'll check if my reverse lights are working later.

Good for you.
So many dont realize that the electrical term "circuit" is derived from circle. Half that circle is positive and the other half is negative. They are equally important in completing the circle or circuit.
Happy moparing