Service Hybrid system, traction control, stabletrak, and brake system message

[varycoolman579]

So I was driving my Tahoe yesterday and a Service Hybrid system message poped up on the dash, no engine light so I thought it was not a serious issue. Today I was driving completely normal and the truck wasent passing 4k rpm and a few minutes the e-brake light turned on as well as the traction control and engine light and a service brake system, service traction control, and a service stabletrak notification poped up. All at the same time. I have an obd2 connector and checked the engine codes, the first one was P0AC4 and the second was P061B if anyone has any idea of what could be happening please help.

 

[GM Customer Service]

Hi varycoolman579,

We're sorry for the multiple warning notifications that you've encountered in your 2009 Tahoe. We recognize you're seeking input from others on the forum, which is great. Although we're not trained as technicians, we'd be happy to look into this if you consider going to the dealer. Feel free to send a PM if you'd like to discuss things further.

Sincerely,

Eddie A.
GM Customer Care

 

[varycoolman579]

I'm taking it to my mechanic thursday

 

[watchsat]

This situation happened to my 2008 Tahoe Hybrid as well, more likely that's the 12V battery is not holding enough charge, which means you need a new 12V battery.

My battery is OK to start the car, when I turned the car on but don't start engine (pairing my tire sensors) for little to long, all different wield error messages came out first, then lost power and won't be able to start engine till I used the external charger to charge the 12V battery.

My assumption is the 300V battery always charge the 12V battery, when the system diagnose there is no enough power remain in the 12V battery, so you never notice the 12V battery is about to quit till you can't cold start the engine...

Wonder does anyone try to replace the 12V battery by themselves? Not sure is that a safe task that you can DIY (since there is a 300V battery in the system, and they are kind of connected)? And heard people mentioned there might be some procedures required after the 12V battery replaced for clean out "lost power" error messages...

Cheers,

 

[soulsea]

Iirc the 300v battery and 12v battery are completely separate and unrelated systems, but please double check before poking around. Generally the systems connected to the 300v battery are connected through bright orange cables/harnesses ... this is an industry norm.

As far as the dash lighting up like a Xmas tree, it happened to me once in the middle of NYC traffic and the truck shut itself down and wouldn't restart for ten or so minutes until the computer went through an entire safety protocol to protect the systems before allowing start up again. Drove it to the dealer and the culprit was a 300v cable not plugged in all the way under the back seat creating a loose connection.

A few other things can trigger the shutdown, most if not all of them require a trip to the dealer. If it's just dash warning and no shutdown then swapping the 12v battery might do the trick.

 

[Hybrid-Theory]

Check the 12V battery, regardless of age, load test it. It may appear to be fine if you just check the voltage but will drop to zero under a load indicating a possible shorted cell. The symptoms you mention are common for a weak 12V battery. The Hybrid computer modules go haywire with a weak 12v battery. The symptoms can be sporadic because the 300V system can eventually boost a weak 12V battery enough that the symptoms come and go.
On a normal/non-hybrid car a weak battery would be obvious long before it caused computer issues because the vehicle wouldn't start/crank slow/require a jump, and you would replace the battery, but the Hybrid tahoe doesn't start from the 12V system, it uses the 300V system to start the ICE.

 

[kskcheche]

Suprised you remembered that soulsea, that was so long ago.

 

[varycoolman579]

My baby had a little accident with a light post last Monday, she won't be back for a couple of weeks. The insurance is taking care of any problems the truck has and will have. Thanks for the replys.

 

[watchsat]

Just keep in mind that dealer may not able to find out that you got weak 12V battery... My car just passed 140 something dealer full inspections 3 weeks ago, then I found out it's about to be dead.

End up I purchased new 12V battery from Costco and replace it, now all those wield issues never come back.