Tank drawings how to unblock the toilet, its very blocked, need a diagram of tank

May be some toilet paper build up that is blocking the drain. Put some water and some additive along with a bag of ice in the holding tank and drive around town. This will break up the sludge and clean the sensors. Then try to drain it again...

The galley holding tank holds the grey water from the galley.

You would need to relocate the tank, brackets and related plumbing.
Recommend you contact Keystone directly here: http://www.keystonerv.com/contact-us

the toilet is the only thing that's dumps into it and its sits on top of the tank

ok, been a while so lets ee if I can get this all down.

1 - Drain water from your holding tank and remove drain plug in hot water heater. Drain holding tanks ( Waste )
2- turn on bypass for hot water heater ( instruction if needed )
3 - Get yourself some winterizing fluid ( can't remember exact name ) from your local Dealer . 2 or 3 gallons should be good
4- Poor this fluid into your water rez tank. All of it
5 - now go around to EVERY tap in your trailer ( one at a time ) and turn on cold water until water runs pink ( or what ever colour fluid you bought ) Close faucet them do the same for hot water tap. Repeat this at every faucet. Even the ones outside if you have any.
6 Don't forget to flush toilet in water runs pink.
7. Ensure all gas vales have been turned off ( tank vales included )

If you did everything right you should be good to go.

Plz double this list to make sure I covered everything

Pull bottom plug out of hot water heater tank let all water drain. Then open all water tank drain valves and be sure your RV is tilted so it will drain towards the valve. Go in RV access water heater valves put it in bypass so no antifreeze can enter water heater tank. Pump RV antifreeze with hose provided into all water lines throughout RV by turning on your main water pump after you have stuck the bypass hose in a new and full antifreeze bottle, then flush toilet until red antifreeze comes out. Open all faucets one at a time until red antifreeze comes out. I use 3 gal but some only use one, the more the better it’s cheap at Walmart. Don’t forget to run outside shower until red antifreeze comes out also, very important or it will crack in the cold. Finally make sure black and grey tanks are empty and flushed at your last camp trip before winterizing. Pour antifreeze in toilet and all drains making sure first that black and grey tank shut off valves are pushed in and closed. Get a quality cover and store RV, it makes a huge difference on protecting roof and roofs lap sealant! All RV antifreeze is non toxic and you just drain it all at your first camp stop after winter! Note: don’t forget to put water heater ionizer drain plug back in wrapped with new white Teflon tape and take water heater valves out of bypass! Draw a diagram of regular mode and winter bypass mode so you don’t forget especially hot and cold water heater blender valve between the two MUST be shut off after you unwinterize
or you will cool your hot water unwanted and have no hot water to use! Happy Camping folks!

Assuming you mean you're going to park it for the winter ????
Start by draining all the water tanks, i.e., fresh water, grey water, black water. Go inside and open all the faucets - if you have one or more where it's a common lever type valve and you swing it left or right depending on desired water temperature, then set it for the middle and turn it full on - leave all faucets turned on - shower included. This will allow the water lines to drain out. DO NOT TURN OFF the faucets - leave them on. Don't forget the toilet tank. If there is still some water left in the bottom of the toilet, pour in a cup of standard automotive antifreeze (ethelyne glycol type) and then CLOSE THE LID of the toilet. Ditto this (antifreeze) for all of your drains. Pour 1 cup of (full strength) liquid antifreeze into all drains (sink drains, shower drain, etc) Finally, make a sign that says "WINTERIZED - PLEASE DO NOT USE" and then TAPE THIS onto the toilet lid.

You have the question we are all asking.
rv tank gauges never seem to be very accurate. The best you can do for your black water tank is to try to see where the sensors are mounted and try to spray water on them to loosen any gunk.
I have had 4 motor homes and never had very accurate tank indicators.
Your black tank can be checked by taking a flashlight with the water off and looking down the hole of the toilet. When it gets close to the lowest part,of the drain hole it is time to dump.

No diagrams available. There should be a tank located under the trailer with a water fill point on the outside of the trailer. Inside under a cabinet there should be a demand pump with an on/off switch located on the monitor panel. There may be a winterizing three way valve between the tank and the pump with a third open ended line used to draw antifreeze into the system. If the valve is in the wrong position the pump will not prime and distribute the water as designed. From there the pump is plumbed into the rest of the plumbing system.