I have a T101 outdoor timer wired to 3 outdoor recepticals. I just replaced the 3 recepticles since they were corroded, and added a 4th in the middle of the line. I also direct-wired a lamp post. Since I did the additions/modifications, the T101 timer will not shut off manually. I thought it was a bad timer, so replaced it, but no change- the line is always hot, and the only way to shut it off is at the breaker box. Would this result in crossing the load and line wires in the recepticals? I tried switching the wires on the first receptical of the line, but no change.

No - you should put the wiring back the way you originally had it: with the black wire going to the brass (or hot or line side) terminal and white wire going to the silver (or neutral)terminal on each receptacle.

My first guess is that you've wired the timer incorrectly. Can you describe what wires you have in the box with the timer in it?

I didn't change the wiring on the timer when I did the replacement and addition recepticals- it has remained consistent. Wiring on box is as shown on box wiring diagram- but will need to go look at it to see what is where. The only variable since the change was the recepticals..?

Remove the "Load" wire from the timer, lights should go out, if not, a constant hot may have been tapped into.
Did old recepticles have a tab connecting both halves of receptacle or any "extra"unknown wire, may be the switch leg.

"Switch leg" yes, maybe- I don't know anything about this...
From the breaker, the line goes to a receptical (I did not change this one), then to the timer; from the timer, to the three old recepticals that I did change and the new one I added. Yes, there was some redundant wire attached that had corroded; the wire used to run to spotlights that were cut off but never disconnected from the receptical... could this have been a linking wire? Is that required to operate a timer? I thought since the timer was at the "head of the line" that it could not be controlled by the load down the line (but I don't know).

Thank you!

Those recepticles may have have been fed by the corroded wire(timer out/load)
Check power to that corroded wire with timer on and off, if it switches, that needs to connect to first receptacle, others shoud? Switch with the first.

I removed all the corroded wire when I replaced the old recepticals. The entire line is hot when the timer is on and when it is "off". So do I need to "switch leg" wire all the recepticals so the timer will work?

OK, now I feel like a super-fool. After considering all possibilities, I looked at how the timer was wired (and how it had been working fine for over a year - the source wire and line wires were not in the right slots. I guess the way the recepticals were previously wired worked with the timer wiring, but when I hooked it up properly, it took proper timer wiring to work - it works fine now that I rewired per diagram :o
Thanks to all who tried to help!

Good Deal.