how to do this on gen 3?

This guy has a video on how to run self diag on gen 2 to check 12v battery health among other things. is this possible on gen 3?

You can perform the same test on a Gen III to check the battery. It works the same as in the video.
You must have NAV since you need an MFD.
1) Apply parking brake
2) Press Power Button twice, foot not on brake pedal. You are now in accessory mode.
3)Hold down Info button on right side of MFD. and at the same time turn Headlights on and off 4 times.
4) A menu will appear on MFD.
5) Select Fault diagnosis to see battery voltage.

 

Thank you duffasaurus, great info. to know. So now that I can check my aux. battery voltage what is it's acceptable or normal voltage range? Mine said 11.5v DC I have always thought a 12v battery should be around 12.7v DC.

 

That seems abnormally low for a new car, unless you have something on? It should read 12.3 to 12.5 at least with no loads. After starting the charging voltage should jump up to around 13.9V. Maybe all your trips are very short with max AC.? The car is still in warrantee, take it to the dealer. I got a new battery on mine, in the first year.

 

I have the same model as you except a 2010 and the battery reads about 11.5v, but this is in accessory mode(pressing power on button 2x with out foot on brake pedal). The accessories are a load. However, when the engine is running and you enter into the test mode, I read 13.8v. which is the charging voltage.
I would take the vehicle to the dealer if you see the voltage dropping below 10.2v and ask for a replacement. Also, I purchased a BatteryMinder Plus model#12117 from BatteryMart.com for $39.95. This device will help extend the life of the 12v battery.

 

One recommendation that I would give when reading the auxilary battery voltage on the Service Screen is to read the voltage directly on the battery terminals first to make sure the Service Screen is giving the correct reading.

When I first checked mine on the Service Screen it showed a 11.7V in IG-ON mode. It had me worried at first but when I checked with a voltmeter it read 12.4V. So I know to add 0.7V to the Service Screen reading.

 

Thanks. That is really good to know when deciding whether to upgrade the DVD or not.

 

I assure you that is not the case. My car came with 10.1 and it works fine. Please follow duffasaurus's instructions carefully.

 

While I am not sure if it is to your advantage to upgrade, I assure you that this works just fine in 10.1

 

I can get into the menu using that procedure but nothing about battery voltages shows in subsequent menus.. Has anyone been able to get further in the mtx pages and read those voltages? Post pictures?

 

To do a true test, you'll need a battery tester. It will give you a voltage read out, while under a load. I think mine draws about 100 amps from the battery. Without putting a load on the battery, it's hard to tell whether it's healthy or not. The test only takes about 2 to 3 seconds.

 

Is there a way to get into any diag modes with the base nav units?

 

But if you do all this your battery is not even near to the open circuit voltage which IS indicative of charge (compensted by temp). Just opening the driver side door triggers that breake master cylinder to be charged big hit on the battery, then you boot up the the car and flash the lights 4 times ??? and even aux mode is some load !!!

are you suggesting that the car already measured it before all this procedure and stored it somehow ??? unlikely since most of the computers are not working at the time.

the open circuit voltage can be meausred on the ODBC port with multimeter, (or scangauge) or on the jump point under the hood as well ... it should be measure after several hours of car was shut off ... the neat trick is to open the passanger side door to do the measurement or even pop the hood

 

11.5 is very low almost dead ... however it would be good to know a few more thing...

1. temperature
2. how long you drove the car day before or when ???
3. the 12V battery takes time to be fully charged a few very short trip over some day can drain more then the HV can charge back.... it takes 45 minutes to an hour to fully charge the battery from a low soc.

What you can do, other then driving, if you can do it safely, to leave the car in ready (lock the door in the driveway) for 45 minutes (engine may come up in lower temp but in summer time not likely of course turn off everything) ... then measure the aux battery 6 hours later ... this would ensure that HV battery had sufficient time to charge the 12V and then all the static charge subsides and then measure with a multimeter (battery tester) ... if still only 11.5 .. then your 12V battery is not healthy.


hope this help