Commodore: Flat battery!

I didn’t note it here, but per a thread on Mastodon, we had to replace the R&J battery that’s in our VE Commodore in about July of 2024, so not quite two years ago. I can’t remember why, whether they did not have the R&J in stock or they talked me into thinking that the Delkor was better, but they used one of those instead… but apparently they’re the same manufacturer just a different “brand” and slightly altered chemistry, and even so there’s really no reason it should be dead after this time.

But on Friday when Sabriena needed the car, dead it was, and dead-dead. Like no lights or any activity when you put the key in, and it measured about 3V with the multimeter. Oops.

So I stuck the charger on it, and then after a few hours we took it in to the auto electricians who previously replaced the battery so they could look at it (and presumably start a warranty claim if the battery had dropped a cell and was still under warranty).

We left it with them, and they took the battery off, charged it completely, tested it, charged it again, and in the mean time did a drain-test on the car to check for parasitic loads. The result? Nothing, absolutely no indication for why this would happen.

They did float the idea that maybe we don’t drive it enough - just tootling around town might not be enough time for the battery to be fully charged back up from the alternator, but to be honest I’m not really sold on this explanation. First of all, this wasn’t a “battery had some slow cranks before giving up”, this was “fine when we used it on Sunday and then completely kaput on Friday with no warning”, which seems unlikely. Second, our driving habits haven’t changed in fully four-odd years, so why would this suddenly happen?

I’m left with two theories of my own, as someone completely uneducated about the field. The first is that the Delkor’s chemistry just isn’t as happy with our usage habits as the R&J was - I think this is also unlikely for the same reasons above. Second, we do (ab)use the feature of our car where the lights automatically shut off if left on when you take the key out… this way we just don’t have to remember to turn the lights on during the day, because the “auto” light feature (the default) doesn’t turn them on on dreary days when I would prefer them to be on for visibility (people seeing us, not us seeing people).

My thinking is that this feature failed, left the lights on, and that cooked the battery… it’s about the only thing on the car I could think of which would drain the battery that fast without warning (they did float the idea that it’s the dashcam, but if the battery is healthy that battery could power it for a month without help).

Anyway, we picked the car up, paid the very-cheap invoice, and off we went… until I got around the corner and noticed I had no gauges and a suspicious lack of lights on the dash. Went back around the block to them, they went “huh, that’s weird” considering they only really took the battery off and put it back, and then proceeded to do some quick diagnostics of it. No blown fuses, no DTCs anywhere, nothing. At this point it’s about closing time on Friday, so we left with the homework to leave the battery off (with the lights on) overnight, to reset the computers (“turn if off and back on again” being pretty sound advice for electronic issues on late-model Holden Commodores). If nothing fixed it, bring it back on Monday and they’ll start hunting for the gremlins.

That didn’t have any effect, so after our usual weekend choring I had a look at it, and spent sime time doing a bunch of research with the ol’ Google. I had memories of cars in the US cooking the BCM and how expensive and troublesome fixing those issues were, and then of course I started getting away from myself worried about replacing the car because it’s haunted… I don’t want to replace it, it really only makes sense to replace it with an EV and they do not presently make an EV for the discerning bogan that doesn’t cost less than half my house.

I did figure out how to put the dash into “engineering” mode (hold the left steering control button in, turn the key on, and wait). I found that with the car running, I had full signals from the tachometer, speedo, temperature gauge, etc, the gauges were just not moving… so that rules out CAN connectivity in my mind, and the problem is likely the dash.

But on a Commodore forum at the bottom of a thread of a whole pile of nay-sayers was a guy who said basically “yeah on ex-copper Commodores they have a stealth button which blacks out the entire dash except the speedo, after a flat battery they can default to on, if you can’t turn it off just unhook the dome light console and turn the key and see if it goes away.”

See apparently the cops thought it might be required for “stakeouts” to sit in the car without drawing attention to themselves, so there’s a button (a big long one in the overhead console) which disables all lights.

Sure as shit, I pop the overhead console out, disconnect two plugs, turn the key, and the car is back to normal… Plug it back in, and the problem returns.

So I’m left with three options that I can think of:

I’m not sure where I’m going to start yet, so at the moment we’re driving around without any dome lights, but the car is otherwise functional. No further battery issues yet.

Update: 2026-04-12: I finally got the motivation to crack open the overhead console (with something like 10 torx screws keeping it together and then a bit of trouble convincing the clips on the sunglasses holder to come apart), and Googling the identification number on the board led me to yet another Commodore forum thread on the subject, wherein at the end of it a user mentioned that despite the fancy little circuit that’s in the overhead console it’s actually not a computer, just a dumb wire for surveillance mode. Clipping the white+red-stripe wire that goes to pin 4 fixed it for them, so after spending some time trying to convince the molex pin to come out, I figured it would not be that hard to solder back together if it was wrong, and just clipped it.

Sure enough, problem solved… so I taped up and heat-shrinked the wires out of the way, reassembled everything, and it’s been right since.

We still don’t know why the battery went flat in the first place though.

Horsham, VIC, Australia

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fwaggle

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Horsham, VIC, Australia

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