Service drivers assistance ?

[Stbentoak]

Has anybody seen this message pop up? I had it during one drive cycle here recently, but it canceled itself over subsequent drive cycles and hasn't reappeared. One thing I noticed during that particular drive cycle was as the engine did not crank over very robustly while I was trying to start it. It almost acted like a low voltage situation that might have thrown this DIC code. I had my battery checked a couple months ago and it was showing as strong. Could just be a one-off fluke. But one thing I've noticed over, say, the last 100 start cycles is that maybe 10% of them It doesn't crank over like the other 90% of them. A much lower turn rate of the starter. It leads me to think the battery could be bad but doesn't test bad. But after 4 years it may be time to just go ahead and switch it anyways....

 

[jfoj]

A new or fairly new battery can be bad, but I typically replace batteries by year 4 as a matter of routine.

Some battery testers just look at internal battery resistance, which can be a valid test, but an old school load test is also really required to get a full understanding of a batteries health. I have been at the auto parts store when the counter guys are testing batteries and look straight faced as they tell the customer the battery is good as it test at 120%!!!! There is NO WAY a battery will test above its rated capacity, you get nothing for free, either the counter guy did not properly configure the battery tester, the battery tester software has programming problems or the battery is bad in a way is causes the battery to test ABOVE rated capacity. Regardless if you are ever told the battery tests over 100%, especially if it is a few years old, time to think about just replacing it because if you are getting the battery tested, you likely are testing because you think there is a problem with the battery anyway.

Low cranking Voltage can cause the high number of onboard computers problems communicating with each other and will really cause a variety of strange issues and warnings. If this is on your Duramax, Diesel's require good cranking current to spin the engine fast enough and put a high demand on the battery during starting, so I would just be replacing the battery if I was in this situation. Batteries are consumables anyway.