Just wandering if your trucks do the same, when you first start it does the voltmeter read around 8 volts with the check gauges light on and after about 20 seconds the voltmeter reads 13 volts and light is off. Thats what mine is doing , it starts fine and cranks ok .

 

Mine is a 96 and it dont do that..

the batteries charge up right away, my voltage is a little low when i crank it at first, but not low enough that the check gauges light comes on... and it goes back up to middle range pretty quick...

Rick

 

not sure, but I would try unhooking you'r heater grids since you propably do not need them right now any way. there almost has to be a very big current draw when you first start it for the voltage to drop that low,so thats where I would start.

 

not sure what heater grids are, is that like glow plugs, that would make sense because when I just turn the key and not start the engine the voltmeter reads just over the 8 mark, somewhere around 9.5 I would guess.

 

it sits on top of your intake plenum and it heats up cold air before it gets into your engine.ther are 2 black wires that bolt onto it ,I have never tested these wires, but I would say that they are both posotive wires. they are about 10 guage wires(about the size of a pencil). I would unhook these wires and insulate them and see if your problem goes away. there may also be another place to unhook them, but I know when these things turn on they really draw alot of current. my lights dim when mine come on.
by the way, you have a nice looking truck!

 

Thanks, I'll try that.....that picture is not my truck, I just saved it there because I was thinking of changing my front bumper to that type. Mine is similar but older, I'll put some pics of mine later.......thanks again

 

Easy way to disable your grid heaters is to follow the two large wires back from the point where where they join the air intake at the top of the engine. They will lead to two relays on the wheel well just a little to the rear of the driver's side battery.
Remove one of the small wires from each relay, they just slip on.

Really no reason to do this though, sounds to me that your heaters are operating normally. They should come on below 50F and below 17 mph for 3 minutes maximum depending on outside temp.