Would like to start the ICE in shop to check ICE

The engine should start a few seconds after pushing the "Power" button. What do you do to get it to move? Also, the 12v battery only provides energy to initially boot up the electronics and to run some of the accessories.

 

you can't. the main battery starts the ice, it's the old chicken and egg.

you need to have it towed to a dealer who can request the special charger from toyota.

alternatively, the grid charger sold in the prius shoppe may work, i'm not sure.

 

I'm not sure where you have been reading, but it must be a bad source. The ICE most definitely is started by the HV (Traction) Battery spinning up MG1.

Wrong! You are not ok there. If you can only drive the car 30 or 40 feet, then there is probably not enough reserve power to start the ICE (a fact to which you yourself attest when you say "It's running on main battery that is just about dead"). You will need the HV battery charged up from an external source before you can go forward.

 

Everything is not ok. I'd stop trying to start it, have it checked out by Toyota competent mechanics. Continued start ups will completely toast the hybrid battery, if it's not there already.

Could even be something like out of gas, but whatever the case, don't attempt to start it anymore, it'll just kill what's left of the battery charge.

 

a lot of learning going on here, should be a fun project car. all the best.

 

see post #4.

 

Reviving the hybrid battery is not just recharge. Imbalance in the cells must be addressed, some cells may be beyond recovery, assessment of the battery requires a not trivial investment in time and learning.

What the typical owner will do is either get a new battery from dealership ( $3000~$4000), or a rebuild ($1500~$2500).

If both those seem out of reach, sell for parts?

 

that's why the toyota charger is regional, too expensive for every dealer to have on laying around.

 

Since this project Prius most likely has no warranty remaining, I say buy a few RC battery chargers, and rebuild your HV Battery pack. Read this thread for complete information.
Gen II Prius Individual Battery Module Replacement | PriusChat

Do yourself a favor and get miniVCI, and a Windows laptop running a 32bit OS of XP or 7.
Read post #2, mini vci question | PriusChat

 

the a/c is electric and does not need the engine.

 

You really need to sort out the HV battery before anything else, otherwise you could end up chasing your tail.

Also, your OP mentioned the 12 V was charged, but check it is in good condition as well and remains fully charged while you start chasing down other faults.