rebrecs

Mikey, agree all points. And you made a good point, that I will look in to further, which is "how different can they be without worry." In other words, is the variance between manufacturers significant. My assumptions have been front and back must be same size, and type (e.g. A/T's versus hiway tires, etc). So, on the front I have 235/80/17 A/Ts, and on the rear I have exactly the same. Fronts are same mfg., rears are same mfg. If Continental makes an AT tire that is 235 tall, and BFGoodrich makes an AT tire that is 235 tall - how different are they likely to be? I dont know. I imagine there is some difference. I also imagine the difference is within the same range as if the front tires were worn down, and the back tires were new. Are you aware of warnings or advice concerning potential drivetrain damage for the difference that could exist based on tread wear?

I run Continental Terrain Contact A/T on GMC 3500 DRW -- on the front. (235/80/17) I had them all around but didn't like that. I don't often get off of the concrete, but when I do, it is not usually into mild mannered grass, or quasi-mild-mannered gravel. It's mud or sand. So I put something else on the back 4 wheels. I wont put anything else on the front, because these Continentals are (IMHO) the best front tires you could possibly have. Especially in Houston where hydroplaning is a serious issue, and they are quiet as mice running high speed. I get yelled at a lot for putting something different on the front and back. But I don't mind. I am very open to hearing the reasons not to do that.

I was beginning to suspect that. Now, things are beginning to make sense. Thank you for sending this along. That sort of puts a new twist on "disconnecting the battery." I'll have think about that.

I have 3500 Diesel 6.6 Denali. There is a battery charging management system built-in from GMC. Based on information in the Owners Manual under the "Battery Gauge" section, there is functionality sounding like what you would expect from a DC-DC Charger w/ Controller. However, the information only discusses the Main battery. There is no mention of how charging is handled for the aux battery anywhere in the Owners Documents. Including the Dura-Max Supplement. There is no charging controller listed on any parts breakdowns either. At this moment I am working from the assumption that either the logic is in the ECM, or the Aux Battery is a well guarded secret. The cranking battery does have a large plastic box affixed to the top of the battery with a lot of high current wiring coming in and out of it. If there is a charging controller, that would be the place for it, and it would look about like that. However, there is no mention of that box in any parts breakdowns either. Do batteries come with big plastic boxes on top these days? I was going to look up the AC-Delco battery model #, but the mystery box obscures the battery entirely. I can tell that changing that battery would not be a fun thing to attempt. So far I have not been able to get that box open. I need a better flashlight.

Here you go ! Everything you need to know. https://www.youtube.com/watch?v=Z9c1hVXBggk

Thanks Snow, I'm sure I do. This is the first I have seen of the terminology "Aux Battery Relay." So far I have seen automatic charging relay (ACR) and Battery Isolator. Something new to investigate. Finding an explanation has turned in to actual work. I appreciate the info you provided. Its a good lead. (no pun)

Hi, I need to understand how the main and aux batteries are related. There is only sparse information in the vehicle User Manual. I believe all of my questions would be answered if I could see a wiring diagram. I found a service manual for my make and model on Helm Inc.'s website. It costs $350.00 Before I spend the $350, I thought I would try this forum. If there is anyone here who knows about the Aux Battery and is willing to chat with me about it - Your help will be greatly appreciated. I want to know how the Aux Battery is situated in both the cranking circuit (if at all) and how the Aux Battery gets charged (charging circuit) Additionally, a somewhat related question would be; What exactly is the Battery Gauge on the dash measuring? (main, aux, alternator, all 3, what?) Thank you in advance for putting up with such a newbie question. Guessing about things makes for bad troubleshooting. Just want to understand what I'm dealing with before I go poking around.