Brake lights stay on when truck is off

I have a 2008 volvo 670 with a d12 motor.
When I shut the truck off, the tail lights on truck and trailer stay dimly lit.( 4 of the 10 led stay barley visibly lit) I have chased this problem to the tractor, as when I unhook trailer only tractor lights stay on.
As well at around the time I had my main engine harness replaced. I now get a coolant critically low warning light on a hard left turn, this in turn shuts the truck down. Usually in the worst spot possible.
I can turn off key and restart truck and it will run normally. The overflow side of the tank has 1/4 or more fluid and the fill side has up to the line where the top and bottom of the tank meet. I am wondering if these two problems coincide with each other as in bad ground or something causing both problems?
Any help would be greatly appriciated
Thanks in advance

 

Is there a fix for this problem ?
I had volvo adjust the peramiters in truck for led lights so that the computer would stop showing open circuit on the lights
But it is draining my battery and would love to get this issue fixed.
Thanks in advance