door locks and power seats wont work for apprx 1 min after rear window defogger has been on.

As long as the rear window defogger is on are those things inop?

Yes,they wont work until the car or defogger is turned off for apprx 1 min.

The only thing that comes to mind is maybe the rear window defroster is stealing the ground from the other two circuits.

where do I find the ground for the rear defogger?

With everything off go back to your rear back window where the rear window defroster grid is.Then take your multimeter and set it to the lowest ohms setting probably like 200 ohms.Then touch the two meter leads together it should read 0 ohms.If it does then ground the black lead of the meter to a good unpainted chassis ground.Then you will see a black wire and purple and white wire to your defroster grid you want to touch the exposed terminal of the red meter lead to the black wire it should read less then 2 ohms.Let me know what you find.