And I have re checked the fuse links and added a ground from battery to frame - frame to block .

 

Until you get the problem resolved, I would bypass any add ons in the start circuit so you are left with the battery; ground and positive cables; starter solenoid; and the cable from the solenoid to the starter.
Check ALL cable connections to make sure that they are clean and tight, the ground cable should be connected directly to the engine block.
Remove both push on connections on the solenoid, use a test push button connected to the positive battery terminal and one of the small threaded studs on the solenoid, if nothing happens, connect the push button to the other small threaded stud. At this point the ignition switch is out of the circuit and the engine should turn over.

The RV battery boost circuit adds additional items to the mix that you don't need to test the start circuit.

 

Ok I changed the ignition switch no change , I rechecked the battery to find it was drawn to below 9.5 volts , so I put another new battery in kept constant power and it would appear after a few other test that the signal wire to starter selonide is not getting power ... if I jump prong to signal post the motor try to start. So if I were to run a jump wire from positive post to the signal post would I then get the motor to turn over is this safe what other options might I have ?

 

Any progress ?
I would temporally bypass any add on 'emergency start' components; leaving a known good battery, battery cable from batt to solenoid, batt cable from solenoid to starter and a neg batt cable from the battery directly to the engine block.
Check all cable connections, making sure that they are clean and tight.
Once you get it starting as it should, add the 'emergency start' components back in; checking each connection as you go.

 

Thanks and I by passed everything putting power direct to starter selonide And the starter turns 1 click and then jams doesn't even try to turn flywheel , I can turn crank by hand so ... I'm going to change the starter a second time with a more expensive one and see if that's my problem now

 

i have a 95 e350 ambulance. i lose all power when i turn the key. checked battery and cables. starter is good. this was a gradual thing. had to jump and would run fine. next time jumped, would run and then just stop. no nothing. had it towed home and noticed that when i turned the key bam no power at all.
i have run out of ideas.

 

did you clean all the connections ?

 

You should have started a new tread for this problem.......

Do you still have the OEM lead connectors on the cables to the battery posts?? The cable can corrode inside the lead and cause the problem your experiencing, When you "clamp" on jumpers, the pressure makes the connection you need. If the truck is shutting down and you have NO power, it's the battery posts, as power for the ECU and other functions all run off the battery, and the alternator just "re-charges" the battery.

If you do, cut then off the cable, and if the cable is very black copper, that's your problem, corroded copper cable. Cut the cable back some, but enough to still reach the battery posts, and replace the batter post with new stainless steel post connectors, like this -

 

That too !

 

95? You won't be able to just cut the pos terminal off if I remember you have 3 large wires in that lead terminal. Does this have the large mitsu alternator? Did you check the voltage when running? Being gradual im wondering if your not charging. And the 215 amp mitsu alt had a problem blowing the 300 amp fuse for the alt.