Chevrolet OnStar back-up battery failure

2007 Chevrolet Impala 1LT
6-cylinder Flex Fuel engine
auto transmission
48,700 miles

Problem: OnStar back-up battery failure

Little red light on the inside rear view mirror, next to the three OnStar buttons turned red yesterday after almost 7 years of being happy green. Consulted owners manual (yep, I actually have read it cover to cover and check it for info when needed.) Manual says to push OnStar button to connect with a rep and have them run remote diagnostic. Did so and spent several minutes quoting from the owners manual to get the idiot on the other end to actually run a remote check. Diagnosis = failing/failed OnStar back-up battery.

Checked with dealership who said it is not unheard of but rather rare for one of the OnStar back-up batteries to fail. Have an appointment for tomorrow afternoon to have them confirm the problem and, if necessary, replace that battery (which turns out to be in the trunk area.)

Some internet research indicates that having the car key in the ignition in the ON position when the car battery is disconnected can cause the separate OnStar back-up battery to fail.

Several months ago I had to have the car battery and battery cable wiring harness replaced due to a defective battery that corroded and fried the positive terminal and positive cable wiring. However, the OnStar has worked perfectly since then except for the intermittent red light now for the past day.


  1. How likely is it there is a connection between the earlier replacement of the car battery and cable and the new problem with the separate OnStar battery?

  2. Why/how would having the car key in the ignition with the ignition in the ON position when the car battery is disconnected create problems with the other battery or any other electrical component of the car?

…still reading, still learning…

Addendum: Dealership quoted price of $94 for the OnStar battery plus an hour labor for installation and reprogramming.

I realize they have to make a profit and the mechanic is entitled to make a living. But an hour labor??? The battery is accessible in less than a minute. I know, because I located it in the trunk by simply removing the liner on the driver’s side of the trunk wall and it is right there.

Okay, so let’s allow the mechanic time to retrieve the car from the service department parking area, drive it into the stall, run the diagnostic to verify the battery truly needs replacement, get a new battery from the parts area (knowing he has to wait his turn possibly), remove the old battery, install the new battery, perhaps do reprogramming, verify all now works properly, push the liner back in place, submit paperwork to the service desk, park the car back outside…

So even though I read online of a DIY guy replacing said battery in 10 minutes after buying it somewhere for $53, I understand that paying the dealership for the job in all fairness costs significantly more. I even understand the mechanic being allowed far more than 10 minutes for the work. (For one thing, how do I know the unknown DIY guy on the internet isn’t exaggerating how quick and easy the job is?)

But an hour’s labor, the battery, tax, etc. coming up to a quote of $226 for a $55 battery that looks to take mere minutes to access and replace? I want to be fair and realistic but I gotta ask…

Realistically, am I off base thinking $226 is way too much for this???

It’s possible that with the key on, that power from the backup battery is routed to something that it wouldn’t normally run with either the key off or key on and the main power source present. Sounds like a poor design, but certainly possible. It may be that your car battery/corrosion episode had something to do with it, or maybe just a coincidence.

Unless the battery is some crazy specialty battery that GM had custom made, it’s quite possible that you could get the battery locally and change it yourself. But there may be some procedure that needs to be followed to ensure that OnStar doesn’t lose any settings or isn’t damaged in the process.

A dealer is usually going to be higher than anywhere else, and certainly a lot more expensive than doing the job yourself, but in certain situations they have the only tools and expertise to do a job. Up to you though—if there are guides to doing it yourself, I’d probably take my chances and save some money.

See if you can access the battery and get a number off it. Enter this battery number into eBays search window and see if they available on eBay…Most batteries are…Most dealerships have a one hour minimum labor charge. That’s how the service department makes money…

Here is one, maybe a cheap fix…

Thank you for the replies and information.

Have done some additional calling around. Apparently changing the battery is the easy part; it is the reprogramming that takes time and hassle. So, I have more research to do to try and find the procedure for the reprogramming. Some places are quoting far higher price than the dealership, upwards of two to two and a half hours labor. And given how persnickity it can be to update computer software, I can understand that reprogramming OnStar might take a long amount of time.

Interestingly, one of the reasons I’ve kept the service is the rate at which cars are stolen around here. OnStar can track the car and disable the engine. However, one Chevy dealer service manager truthfully told me that in every single case of a stolen Chevy they’ve seen come into their shop for repairs after being recovered, the OnStar had been disabled and the car was not found via OnStar and that the cars were so badly trashed that no one in their right mind would want the car back. He honestly said that he and his wife had dropped OnStar and gone with having good cell phones and AAA. That’s some real food for thought.

That service manager had put me on hold while he talked with a technician to find out that it is the programming that is the real labor issue and that no other systems on the car are affected if that battery isn’t working. He suggested that if I don’t choose to replace it that I disconnect it though.

Gonna also see how much my car insurance goes up if I just drop OnStar and save the money of both the replacement and ongoing cost of having OnStar at all.

I’m thinking either properly replace it or remove it so that there isn’t a bad battery sitting back underneath things in the trunk where it could leak or cause other problems???

It is hard to say if the earlier battery replacement had any thing to do with the early failure of the memory battery. I would suspect it didn’t and here is why. When replacing a vehicle battery the ignition isn’t normally turned on when while removing the old battery and installing the new one. As for the issue of running down the memory battery while the ignition is turned on with no vehicle battery the issue may be because the memory battery is tied directly to the vehicle battery. This would mean power from the memory battery would be the only supply for power if the ignition switch was turned on and it would have to supply much more current than it is normally supposed to and therefore drain the memory battery. Memory batteries are usually made from lithium and have about a 10 year life span normally.

You sound like a pretty resourceful person Marnet and it seems to me you could replace the battery yourself and by using a backup power source you could replace the memory battery and not lose the programming while replacing the battery. You just need to connect a battery pack of the same voltage as the memory battery to the battery leads of the memory battery. If the memory battery is 3 volts you could use 2 flashlight batteries in series and connect some wires between the batteries and the connection to the memory battery leads. Pins on the ends of the wires could be used to pierce the wires of the memory battery to make the connection. Be sure to verify the battery polarity is correct if you do this and make sure nothing shorts the supply connections.

Thank you for the explanation and idea on doing it myself. I just may end up dealing with this on my own. Generally speaking, any car work is beyond my physical abilities due to arthritis. But this is a small, not heavy, easily accessible battery. So I just need to think this all through thoroughly. GM is very proprietary about the programming info which doesn’t surprise me. Worst case scenario, I either forget about having OnStar (which wouldn’t be the end of the world, afterall I drove for 31 years without it before getting this car!) or pony up the money to the dealership. But I’m not at either option yet. :slight_smile:

Thanks again everyone for the feedback. It DOES help.

…still reading, still learning…

I wonder if the OnStar unit has a SIM chip in it like most cell-phones…If so, you might be able to buy a salvage unit for a few bucks and just swap the SIM chip with yours, which is correctly programmed…This site has links to instructions for changing the SIM …I bet you can just replace the battery in your unit without the need for any reprogramming.

Ah, now I hadn’t thought of that but it makes sense it might have a SIM chip. Thank you!

May I ask, what website did you find that info on, please?

I thought I posted it…

Then I found this…

"OnStar uses the Verizon Wireless network. So it’s CDMA, not GSM. Which means no SIM card like is used on GSM networks. If you don’t already have bluetooth, you may want to look at switching out the OnStar module with BlueSTAR 2010 -

If it were mine, I would try replacing the battery myself and see what happens. Otherwise I would keep my $200 and live without it…

Thank you!

Well, after lots more research, talking with my insurance company about advantages/disadvantages of having OnStar, etc etc etc, have decided either to let the dealership do the professional job or simply forget it and do without it completely. Still weighing some factors on that.

Thanks again everyone for the responses. They have been helpful and I do appreciate the feedback.