electrical problems with 1995 white gm volvo intregal sleeper

Hi Guys and gals, maybe someone can help me.

I bought a used 1995 white gm volvo a few years ago and have had a lot of trouble with check engine light, fluid light coming on, blinks mostly. Seems to only get worse when pulling a load. The truck balks a lot when pulling a load. I have a wilson triaxle so at the most I am hauling 30-34 tonne. I have had this truck in a volvo dealers shop off and on trying to get this problem fixed. Seems they dont really know how to fix the problem too well. After spending almost 4000 dollars on repair bills I am just about at the end of my rope. I know the easy thing to do would be is to get rid of it but I only use this truck once in awhile to haul grain. I'm not in it every day. Its a bit scary pulling on a highway as I'm afraid its going to quit on me before I can get in the lane but it happens mostly as I am getting up to speed, usually around 15-1700 rpm. Sometimes when I am going highway speed the fluid light flashes on and off then sometimes it stays on and I am having to slow down and such. Sitting idling the light will flash then the truck quits. this does not happen all the time but it's a pain in the butt. Maybe someone out there has had past experience and can point me in the right direction to get this thing fixed. Thanks for your time. Oh its a D12-425, VOLVO Syncronised Transmission maybe this helps.

 

Fluid light on dash stays on truck quits after about 30 seconds. I disconnected battery over night still having same issues. The fluid light stays on plus 27 code comes up. I took the truck to an independent repair shop last year and they spent a lot of time tracing back through the wiring. They removed some kind of box under the dash but I don't have it. They thought it might be some kind of tracking thing but I'm thinking maybe it was the module that controlled power to the ecm. All the lights and accessories work. I drove the truck back home last year bobtail no issue with the fluid light. When I attached the grain trailer after about 15 miles the fluid light started flickering again and after awhile while driving to another job the truck died on me on the road. I was able to get home but the truck has sit for quite awhile. I went out a few days ago just to run the truck to move it but like I said the light stays on so I'm no expert on this I need some serious help and no bs for a change. I can't believe a company would go out if its way to make such a crappy product

 

Looking for Pablo here maybe he can help

 

Well I can try checking the coolant but I would have to use strips? Plus get a new cap on the recovery tank I guess. I'll phone the guys that worked on it last year and see if they can come out but I can't drive it there it's over 50 miles (80 kl) hell will try anything if that's all it was..... Where is the coolant sensor located?