First of all, this site is great. Tons of info and very helpful people. I have searched but I am still not for sure of my situation. I will try to explain it clearly.

I have a basement bathroom roughed in when built 3 years ago. Looking at the pipes in the floor there is a 2" coming out of the ground(Sink I assume), roughly 20 inches or so to the right is a 3" coming out of the concrete(toilet I assume) and then a 12"x12" square with a 2 inch pipe running through the hole (Shower I assume) roughly another 20" away. There is no p trap or anything, just a pipe running under the cut out all the way through and under the concrete.

I have a pit already built in with plumbing capped off above it that runs under the main floor to the waste pipe. This is where the ejector pump goes I assume. There is also a 1 1/2 inch capped pipe that is to the left and around the corner that I assume is the vent line for this pit.

My main concern is venting the sink, toilet and shower. I do have a 1 1/2 in capped pipe (PVC) above this area. I assume this is to vent all three. I am not for sure how this is suppose to work. It goes up through the main floor between the walls of the two upstairs bathrooms. I believe this connects to the main vent stack above the upstairs bathrooms as well. Is this correct and will it work as a vent for the bathroom in my basement. From what I have read I need to vent the sink before the p trap with this 1 1/2 PVC pipe and the toilet and shower will be wet vented from this? Am I correct? My last resort is to have a plumber come over and tell me what I should do. I don't want to spend the money if I don't have to.

Thanks for all your help guys.

Save your money. I think I can explain things.
My main concern is venting the sink, toilet and shower. I do have a 1 1/2 in capped pipe (PVC) above this area. I assume this is to vent all three. I am not for sure how this is suppose to work. It goes up through the main floor between the walls of the two upstairs bathrooms. I believe this connects to the main vent stack above the upstairs bathrooms as well. Is this correct and will it work as a vent for the bathroom in my basement.
You are correct. The capped pipe vents your bathroom group. It goes down like this.
Toilet connects to the ejector pit Lavatory connects to toilet drain and runs a vent off the top the stubout tee out the roof or revents back into a dry vent in the attic.. The toilet wet vents through the lavatory vent and the tub/shower connects to the lavatory drain and is wet vented by it.

then a 12"x12" square with a 2 inch pipe running through the hole (Shower I assume) That hole is a tub dap out for a bath tub. However, if you wish to convert to a shower extend the trap raiser a few inches above the floor line and fill the hole with cement.
Sounds like you're going to be just fine. good luck, tom

Thanks for your answer. That makes me feel much better.

I do have another question about the vent for the lavatory. Do I just Tee off the top off the piece in the concrete and run one line to the p trap and the other straight up the wall to the capped vent piece?

Is it OK for this vent to have 90 degree bends in it or should I use a couple of 45's? The reason I ask is because this pipe will need a couple and so will the vent over the ejector pit.

Thanks for your help.

Sorry for another question guys. I just read another thread about the ejector pit needing its own vent line out of the roof. Is this correct. I only have a 3 in vent pipe in the roof. I assume the capped vent line above the ejector pit connects to the main vent stack in the attic. Is this not code? Do I have to run a horizontal vent line out of the side of my house? I sure hope not.

Thanks guys.