Partial Answer Bed heats up then it shuts down

hello, guys,first of all sorry for my bad English, but here is my issue, the bed would heats up to 40 c and then it stops. I have read something about being a safety shut down but that's it, and that was with the extruder, so I assume the same thing is happening here. I checked the thermistor and its reading ok( I assume) I have checked the resistance of the temperature sensor, it's about 140k ohms, which I read somewhere it should be reading around 100k ohms. So I think the temperature sensor is ok. For the bed resistance should be reading around 14 ohms, which is getting around 13.5-14.8 which I also assume is ok. I have checked the voltage and as it's heating up I'm getting 13. 5 volts( I thought it should be around 12) but anyways a soon as it gets to 40 c it stops heating. What else should i check

 

It just say something like this
"-> M105
<- T:23.0 /0.0 B:25.6TO:23.1/ 0.0 @:0 B@:127"

 

What version of the printer do you have? Is the power and thermistor cable flat and feeding out the back or is there a molex-style connector hot glued under the front with round cable running through the middle plate?