Engine check light is always on.

When you disconnect the battery you clear the SUV's computer of the fault code or codes. After you start the car and drive it, the PCM or computer, get a bad reading from one of your vehicle sensors that something is out of range and turns the CEL on. You must scan the computer for codes with a code reader to find out what code the computer has stored in it's memory. Once you have the code we can begin to diagnose which sensor or problem that is making the sensor read incorrectly.

If the vehicle is running fine and you just have the light on, you can drive the car, and no damage will be done, just that it isn't running very efficiently and can be an emmision sensor. Most times though with the CEL light on, you will get driveability problems.

get the code read so we can help

Dont drive too long or you could cause more damage. If you have a misfire code or a map sensor code you could be running rich which would cause damage to the catalytic convertor. Get it checked out so at least you know whats goin on

the code reads" P1345 camshaft to crankshaft position correlation faults" This is the code that I got from the PCM. What does this mean?

PCM is detection your engine is out of time. Meaning your timing chain is worn and streatched, jumped a tooth, or one of the sensors could be bad. Crank position sensor or cam position sensor. How does the truck run? Any lost power? Pinging? Lopeing?

Yes Sir the truck is losing power when it is in the 1st gear.

Your timing might have jumped a tooth. I would definatly have that checked and replace the chain and gears. It it snaps you could have alot worse problems if it is an interferance motor (means your pistons will smack your valves)

Check engine light came on n its losing power! Sounds like it wants to shut off wen im sitting at a light!