CAN voltage less than 5 volts combined

[brcisna]

Hello All,

This is not exactly HP Tuners specific but,,hoping someone may be able to shed some light,,for a newbie,,, in regards to what I think,the CAN bus voltages on a 2010 Chevrolet Suburban seems to be too low i recently purchased,,that has a rough idle
Bottom line,should the total between CAN-HI & Can-LO with key on,not running equal 5 volts,, grounding to either IGN,,grnd , or battery grnd 4 & 5 pin of DLC.
Read somewhat conflicting articles on this some saying the two values measuring these readings ,, at the DLC,should be almost exactly 5 volts,,, combined , when the next article claims it should only be 'close to' 5 volts total.
Just learning the ropes on CAN bus theory.

My particular truck,,,
CAN-HI = 2.6 volts
CAN-LO = 2.1 volts --- .3 volt less than the 5 volts combined.

..or is this an ok scenario?.

To the point i think i am going to purchase a low end table top/portable oscilloscope and try and see what i can see with this device plugged into the CAN bus.

Thanks

[GHuggins]

CAN always toggles rapidly. High around 2.5 and Low around 2. Looks good to me. You would know if there was an issue. Lots of things wouldn't work.

[gtstorey]

Pretty good explanation of the GM system.
http://resources.aeswave.com/ATG-05_...%20may%20occur.

[TheMechanic]

Hello All,

This is not exactly HP Tuners specific but,,hoping someone may be able to shed some light,,for a newbie,,, in regards to what I think,the CAN bus voltages on a 2010 Chevrolet Suburban seems to be too low i recently purchased,,that has a rough idle
Bottom line,should the total between CAN-HI & Can-LO with key on,not running equal 5 volts,, grounding to either IGN,,grnd , or battery grnd 4 & 5 pin of DLC.
Read somewhat conflicting articles on this some saying the two values measuring these readings ,, at the DLC,should be almost exactly 5 volts,,, combined , when the next article claims it should only be 'close to' 5 volts total.
Just learning the ropes on CAN bus theory.

My particular truck,,,
CAN-HI = 2.6 volts
CAN-LO = 2.1 volts --- .3 volt less than the 5 volts combined.

..or is this an ok scenario?.

To the point i think i am going to purchase a low end table top/portable oscilloscope and try and see what i can see with this device plugged into the CAN bus.

Thanks

Kind of like A/C electrical you have RMS (Root Mean Square) as opposed to Peak To Peak values.
953Eb.gif

[blindsquirrel]

I'm not aware of any scenario where CAN issues would show up as a rough idle being the symptom. Horses, not zebras.