I believe 308 was the number anyways, book mentioned glow plug circuit. Truck starts right up and runs fine. Glow plug indicator lights up. Engine light will go out after a few key cycles but returns a few days later. Will a bad glow plug cause this? or is something else going on? Truck is an 04 with 33k. Thanks.

More than likley a 380 code, which is glow plugs. 308 is #8 cylinder. You probably have 1 or 2 bad glow plugs. TrucK will start fine with all glow plugs bad unless you get in really cold places

OR the glow plug relay, I beleive p0380 is Glow plug feedback code, usually the relay is burned out.

get a test light, attach one end to glow plug on cyl #2 touch other end to a ground.

have an assitant turn key to on position ( engine must be cold for this to work )

if no light, the relay is at fault, if light then you have to test each glowplug seperately.

Testing individual glow plugs requires removing the buss rail from each side

and attatching test lightclip to pos post of battery, touch tip of each glow plug with test light, if it lights, glow plug is good.

Possible:

P0308 - Cylinder 8 Misfire Detected