Able to get voltage from OBDII?

aoLhaTer · 01-17-2005, 03:52 AM

Im a total newbie to OBDII stuff since the car Ive had was made in 93

Im going to be getting an 03 or 04 G35 soon and this will of course have OBDII

I was contemplating the possibility of instead of getting a seperate voltmeter, just using the carputer to display voltage
Would this be possible through OBDII?

Thanks in advance

DavidL · 01-17-2005, 09:43 AM

Battery voltage is typical in a scan tool. No problem.

Gibson99 · 01-17-2005, 11:35 AM

but it's worth mentioning that lots of cars do NOT have a 12v pin in the obd-ii port. also, the ones that do - it's hot all the time since it's a direct (often UNfused except for the monster 150 amp main fuse) lead to the battery.

not recommended as a place to permanently connect a voltmeter. i mean, unless you LIKE jumpstarting your car all the time...

Zac · 01-17-2005, 03:53 PM

I think what he wanted to know is if voltage was something that the OBDII protocol could report. I hope he wouldn't try to hook up a voltmeter there at least. :-P

aoLhaTer · 01-17-2005, 03:58 PM

Ya ksmyarse is correct

I want to get voltage displayed on my carputer LCD and I was wondering if OBDII could report that

DavidL · 01-20-2005, 10:21 AM

Back to my first post in this thread. Yes, battery voltage is available on most scan tools (which isn't contingent on 12 volts being on the OBD2 connecter)

god_of_cpu · 01-20-2005, 10:32 AM

Quote: Originally Posted by DavidL

Back to my first post in this thread. Yes, battery voltage is available on most scan tools

It is? Battery voltage is NOT one of the defined PIDs readable from the OBDII standard. http://www.obddiagnostics.com/obdinfo/pids1-2.html If a scan tool is showing the voltage its either doing it through reading an extended code not garunteed to be on most cars or through another means. What scan tool did you use that showed this information?

Oxygen sensor voltage IS available through OBDII, but that has nothing to do with the electrical systems voltage or health.

DavidL · 01-20-2005, 11:58 AM

God of CPU,
If you note, I didn't mention OBDII. I mentioned Scan TOOL. www.obd2.com (Ease Diagnostics) is one, Vetronix, Terradyne, and many others show voltage as a matter of normal course as it is fundamental to vehicle diagnostics.

Regarding O2 "nothing to do with the electrical systems voltage or health" If the wiring harness is broken or resistive - that will affect 02 results. I do understand that it's not battery voltage...

I don't call the majority of the boxes that get discussed here "Scan Tools". They are much more limited in their capability to be considered a "Tool". They are more in my opinion to be "OBDII read out boxes"....matter of symantecs, but important. Real Scan Tools costs $3000 and up. The new breed which are vehicle interface boxes that are networked with PCs will be around $7000 for a complete solution (and worth every penny to someone who uses a "Scan Tool" for their livelihood).

This just goes back to the loose understanding of what OBDII is (a regulation) and what a protocol is, and what "black boxes" support.

EDIT: attached is a printscreen of what one "Scan Tool" can provide. Note Battery Voltage is listed at the bottom. Battery charge target voltage, battery temperature, and other battery related data is also available.

god_of_cpu · 01-20-2005, 12:12 PM

DavidL,

Nice Recovery!

jyaron · 02-03-2005, 04:51 PM

Quote: Originally Posted by god_of_cpu

It is? Battery voltage is NOT one of the defined PIDs readable from the OBDII standard. http://www.obddiagnostics.com/obdinfo/pids1-2.html If a scan tool is showing the voltage its either doing it through reading an extended code not garunteed to be on most cars or through another means. What scan tool did you use that showed this information?

Oxygen sensor voltage IS available through OBDII, but that has nothing to do with the electrical systems voltage or health.

Closest match.....

ref: SAE J1979 Revised APR2002
Control Module Voltage
Mode $01 : PID $42

planethax · 07-18-2007, 09:26 PM

Just a note, using an elm327 device, AT RV command will give you system voltage