Fellars,
Any ideas what I'm dealin with? When I turn on the truck an wait for the glow plugs, my battery gauge flickers from about 8 volts to normal, the lights dim to high and low. It continues for about 20 seconds after the glow plug wait light goes out. The guy I bought It from said to wait in the winter to start it until it stopped flickering. Any ideas.
In a maybe related matter, seems like now the truck is not charging the batteries. I'm going to replace one of them that seems to be the worst, but someone suggested that its probably the alt... What ya think..

Thanks

Atom

 

the voltage drop in noraml when u cycle the glow plugs

 

I would never replace just one battery but hey. When the WTS light goes out, you turn it on. The PO probably knew it had a issue and that is the reason for the waiting statement. You will need to load test the batterys, test the voltage output of the alternator, and check the GPs. What do you know how to do? load test will be easiest at an autozone or similar. the can usually do it free along with the alternator.

 

youre a glowplug joe hahaha, just kidding hehe.

 

That's completely normal. This is your glow plugs cycling on and off to reduce smoke when the engine is first started (AKA "after glow"). The PO just didn't know what it was and assumed you wait for it to stop.

Start as soon as the WTS light goes out as wreckingball says. The flicking will continue for a short time to help the first few cycles of the engine and reduce smoke. If you're able to continue starting the truck many times without manually charging your batteries then they are charging; it doesn't take much to drain them in these trucks, but if you feel its turning over slowly than get them load tested and replace both if they're bad.

Forgot to add: Check how clean your terminals are, it makes a HUGE difference at the kind of load these trucks put on the batteries. Clean posts, clean connectors, and tightly fastened too.

 

Glow plugs draw just under 200 amps when they heat.
Depending on which starter you have, the draw cranking is anywhere from 200 to just over 300 amps.

All electrical connections MUST be clean and tight.
Batteries should be at least 850 CCA rated, bigger is better if you are in the north/cold climate country.

What year is your truck?
You should also inspect the battery cables, passenger side positive terminal clamp is a weak point where all the electrical systems tie together.
If the positive cable insulation looks like it has been hot, you probably have corrosion inside the clamp and cable, time for a new one.

Also follow the wiring harness to the engine, depending on the year you have a pair od orange/white or orange/green or tan or yellow large AWG wires in the harness.
The connector where the truck harness plugs into the engine harness near the dip stick is another weak point.
If that connector looks like it has melted on the end with the big wires, you have a problem there.
Those two large wires carry glow plug power from the battery to the glow plugs.

Depending on the year, they could also be hot at all times. (87 and later)