Driving down the road. Turned on heated seats and a couple minutes. Truck quite. Lost fuel gauge shift indacatr. No start. No power to fuel pump.

you don`t say how you know it has fuel. did you check the fuel pressure with a gage and did you check the fuel volume as well. this sounds like a fuel pump problem.

i would check three parts , i have seen a weak ignition coil make this happen, change fuel filter and last possibly either fuel pump or fuel pump regulator

cheap fix .....crank sensor is bad $60 bucks

have the crank sensor checked also check the fuel system for correct pressure

Sounds like a short in the fuel guage circuit or fuel guage sender unit. check all connections are good. check no water got into connections.

check the fuses. they are under the back seat just pull up on the lower part of the back seat and it will come out. fuse box is on the drivers side. check to see if water is getting in that could be the cause.

It is normal for the pump to run for two seconds when first switched on to pressurize the fuel system. It will turn on again when cranking and while running. I would still suspect the pump given your symptoms, however other problems could also give you the same symptoms. If it is the original pump from 2002, or more than about 7 or 8 years old, I would definitely replace it, and the fuel filter. Often the pump will go intermittent. I had one that I could restart and get down the road by hitting the bottom of the gas tank a few times!

If wires came off oil pressure switch or if switch went bad, it would shut down truck immediately. Your oil pressure switch performs 2 functions; oil pressure to gauge.light and it's also a safety feature that if you're in an accident or rollover, when oil pressure drops it shuts off power to fuel pump. I'd start there. The reverse is also a possibility, if fuel pump fails, truck shuts down = no oil pressure.

With a diesel I'd have to look in to the fuel system. I'd check the pump first. I know from personal experience when a fuel pump dies on a fuel injected engine there is no warning... like someone reached over a turned the key off.
I hope this may have helped,
Tom

There is a sensor device, on the right side of the engine block near the front, for the oil pressure that has two parts to it. It is used to control the oil pressure guage on the dash as well as having a switch which has wiring going to the Electronic Control Module, and this ECM input has a software time-out safety feature. After the engine is started, if the indicated oil pressure goes too low or is lost, the voltage to the fuel pump is shut off. This is desired in the case of a crash. This event will cause the engine to quit. On my manual transmission vehicle the ECM will reset if the ignition is turned off for a couple of seconds. It sounds like this oil pressure (aka sending unit) sensor is not working properly, causing the fuel pump power to be removed.....(probably intermittently). About $20 and a few minutes to change if you can get your hands down in there.