CAN low voltage too low
Thread Starter
Teching In
Joined: Feb 2023
Posts: 14
Likes: 2
CAN low voltage too low Hello,
2010 Chevrolet Suburban idles very rough after AFM/DOD delete,, checked compression all 160 psi even across the cylinders
Bought this truck 'as is' knowing of the rough idle situation. The previous owner after doing the cam lifters replace done the AFM/DOD in ECU delete with the supplied DiabloSport Preditor 2. Stock non DOD cam. AFM Racing deluxe kit
After doing some recent checking my Autel entry level handheld scanner would sometimes view the data stream,,and many times would only show half the available pids. Bought a second cheap OBDII ,usb dongle to try as a backup.This reader does the same. Sometimes read data sometimes does not.Both these units work fine on my old 2003 Suburban,
Yesterday done some voltage and resistance checking at the DLC,and with key on battery voltage 12.6 v ,,CAN high shows 2.55 v ,,but CAN low is only showing 2.1v
Anyone have any ideas how to probe backwards on CAN low network. This voltage does diffinately seem too low.
Visually looking all the ground straps motor to chassis looks connected per the GM wiring schematic i was able to conger up.
Ideas.
2010 Chevrolet Suburban idles very rough after AFM/DOD delete,, checked compression all 160 psi even across the cylinders
Bought this truck 'as is' knowing of the rough idle situation. The previous owner after doing the cam lifters replace done the AFM/DOD in ECU delete with the supplied DiabloSport Preditor 2. Stock non DOD cam. AFM Racing deluxe kit
After doing some recent checking my Autel entry level handheld scanner would sometimes view the data stream,,and many times would only show half the available pids. Bought a second cheap OBDII ,usb dongle to try as a backup.This reader does the same. Sometimes read data sometimes does not.Both these units work fine on my old 2003 Suburban,
Yesterday done some voltage and resistance checking at the DLC,and with key on battery voltage 12.6 v ,,CAN high shows 2.55 v ,,but CAN low is only showing 2.1v
Anyone have any ideas how to probe backwards on CAN low network. This voltage does diffinately seem too low.
Visually looking all the ground straps motor to chassis looks connected per the GM wiring schematic i was able to conger up.
Ideas.
On The Tree
Joined: Jul 2020
Posts: 119
Likes: 15
brcisna, I am not sure if this will help you but i was having a issue with my DD gauges communicating with the CAnBus (2013 E38 ECM). The link below describes my trouble and solution. Basically I needed to add another 120 ohm resistor to the BUS....
link: can-data-wires-question
good luck!
link: can-data-wires-question
good luck!
TECH Fanatic
Joined: Jan 2018
Posts: 1,251
Likes: 239
From: Dade City, Fl.
check this out I think i would start by removing the battery (to make sure there are no modules being powered or active) then check the resistance of the high and low can circuits and compare
Thread Starter
Teching In
Joined: Feb 2023
Posts: 14
Likes: 2
thank you for the link @jetech
From watching a lengthly can bus video from Scanner danner a week ago,,he claims the two readings you get between CAN-HI & CAN-LO,,,should in fact be exactly 5 volts... Others say it only has to be 'close to ' five volts,,, I have checked the resistance as in this article you posted,,I am going to unhook battery and recheck though.
Just seems odd the obd2 scanner reads and then doesnt show all the pids over half the time..I borrowed another scanner it does the same thing also..
Thanks again
From watching a lengthly can bus video from Scanner danner a week ago,,he claims the two readings you get between CAN-HI & CAN-LO,,,should in fact be exactly 5 volts... Others say it only has to be 'close to ' five volts,,, I have checked the resistance as in this article you posted,,I am going to unhook battery and recheck though.
Just seems odd the obd2 scanner reads and then doesnt show all the pids over half the time..I borrowed another scanner it does the same thing also..
Thanks again
