The up function on the left window quit so i pulled the door trim and tested the motor with jumpers and concluded it was the switch. The new switch will put the window up but not down and the old switch will put the window down but not up. Switch is the type with a latching function for auto power down. Checked both switches with DVM old switch tests good fr down and no good for up. New switch tests good for up but not down. Could the new switch be bad or am I missing something.
Sounds like the new switch is defective. Doesn’t happen often, you just got unlucky on this one.
Check at the motor with the switch in a neutral position,both terminals should show ground (no open) push the switch one way power appears at one terminal push the othe way power appears at the other terminal. I bet when sitting in a neutral position you are losing a ground. See what you have. I conclude switch is brand new? what else could it be but the switch,I wonder?
In my experience, things like this usually result from a misunderstanding of how things are supposed to work, but I must say that it certainly sounds like your new switch is defective. You might consider taking the old switch apart which should make it clearer how it is supposed to work, why it has failed, and whether your test of the new switch is valid.