Put it on jack stand. If the four wheel does not engage pull the cord on it and see if you can engage it manualy. If that works the actuater is bad and not pulling the cord.
by jumping wires across
Fuel pressure test.
There is a switch on the transfur case that sends power to the front differential 4x4 Actuator when you shift the 4x4 lever,need to check the switch with a test light to see if it has power going to it. If not then check fuse in fuse box for the 4x4, If it does have power going to it, then go to the front housing and check the Actuator with a test light to see if it has power going to it, if no power then problem is in the wireing from there back to the transfur case switch. If you do have power at the front, then replace the Actuator.
Need to put truck in 4x4 with engine off, transmission in park key onTake a test light and check the wires on the Actuator, and see if they are hot.If they are hot Then replace the 4x4 Actuator in the front housing.If they are not, Then check the 4x4 fuse
First uf all, The computer has nothing to do with the 4x4 on this year truck. If your check engine light is on , Then there's a problem in the system wiyh the engine or transmission, Not the 4x4. You need to check the 4x4 Actuator on the front housing to see if it has power going to it when you ingauge the 4x4. Check it with a test light. If it lights up the test light, Then replace the actuator in the housing. If it don't. Then go to the top of the Transfur case and you will see a switch on it. Check it with a test light, With the 4x4 ingaged, if its hot there then replace that switch. Before you do anything check the 4x4 Fuse's in the fuse box with a test light.
Have a fuel pressure test run.
Probably the fuel pump is on its way out. Have a fuel pressure test done.
Could be a number of reasons. I'd recommend you take it in to a shop and have a system performance test done on it. While you could do it on your own with a manifold gauge set, you would have to be able to decipher what the pressure gauge readings indicate is wrong with the system.
If it's vacuum (has hose) just apply vacuum.
Well, I'm sure you can answer that yourself. You (the QuestioNer) are just a boasting person. You ain't gonna test us don't U?
If it has lock out hubs, Then you have a bad lock out on one side are the other. If it does not, Then the Actuator on the front housing is not ingaugeing. Need to check that with a test light. If it has power going to it , Then replace 4x4 Actuator. If no power then check 4x4 fuse in fuse box.
you might be burning it. obvious sings would be a poof of smoke on start up or water in your oil. less obvious would be to have a compression test done also check to see if your passenger floor is wet might have a leaking heater