If one of the batteries is bad.....

[E'sStrokr01]

......Could the truck run bad too? Or run good someo of the time and run bad the remaining times? I'm thinking about going to Advance, or Autozone and having the driver's side battery tested???

Why are there two batteries anyway? And what do each control, or send power to???

Thanks!!!

[ianstew]

It takes alot of juice to crank A PSD, they run high compression. If one battery is bad, you should replace both. never replace just one battery if you can help it. they are simply tied together, there are no controllers or isolators.

[layson]

Yes one can go bad and it will take the other with it shortly. Make sure when they test it that they unhook both batteries. They are coupled together and if they test them that way they will probably show up fine. I had one that was 6 V and the other was 12.. ended up taking out the alternator too.

[E'sStrokr01]

Good Info.

So if one or both batteries are going bad, could the truck start running bad, or intermittent?

[layson]

I don't know about that, but you sure can tell when you try to start it? What issues are you having?

[Rob]

hopefully a tech wil chime in soon, but i agree with what was said above, if you are going to replace one, you may as well do both...

[ianstew]

Is it an Excursion???

[layson]

Don't forget to check all your connections too?

[blowinsmoke7.3]

what kind of batteries are they? How long have you had them? Is there any corrosion on your terminals?

All of the above can have some sort of impact on performance

[E'sStrokr01]

Originally Posted by layson

I don't know about that, but you sure can tell when you try to start it? What issues are you having?

Truck starts up just fine, and runs well for a while, then sometimes starts to lose power, then gets sluggish and runs really rough. This seems to happen most of the time whenever I'm going along about 70 or so, then whenever I gradually accelerate, and start to spool up some, it develops a miss, and will run choppy, while losing a LOT of power.

I'm learing about the diesels and don't know that much about them right now, but it almost seems to have a small squeak, maybe from the serpentine belt? Do the 7.3's have serpentines than run everything? Sometimes the power steering seems to be sluggish around tight turns in parking lots, etc. Sorry for the long wind but just trying to explain what's happening.

Is it an Excursion???

01' SuperDuty Lariat CrewCab