I'm currently trying to hunt down a problem I'm having with the obd2 port on my 01 Tahoe. I tried to get it inspected this morning and the state obd tool could not communicate with my obd port. I took the car back to my shop and hooked up my autel scanner to see if the obd was dead and to my surprise I was getting full obd functionality. i was able to run codes and read live data with no issues. I then attempted to take the tahoe to a second inspection shop and encountered the same issue of the state obd reader not being able to communicate with my ecu. i then took the tahoe back to my shop and tested the power and ground pins at the obd port and was getting a healthy 12.6 volts on pin 16 and good ground on pin 4. the next thing i was told to test was the resistance between the can low and can high pins but unfortunately my obd port only has the can low pin 14. there is nothing in the can low pin 6 port. At this point im truly at a loss on what more I can look at. I'm truly confused on how I can get full functionality from my own scan tools and have access to all the ecu data but somehow the state inspection computers are the only computers my obd is unable to communicate with. any advice would be greatly appreciated.

 

Told by whom?
Your truck uses single wire Class 2 serial, not CAN.

Make sure both ground pins have a good path to ground. Measure the resistance with a meter.

This is the second or third time I've heard of testing facilities not being able to hook up. I think their equipment, or operators, are just junk.


https://charm.li/Chevy%20Truck/2001/...%202%20Device/

 

really appreciate the quick reply. thats some helpful info for me to look in to. hopfully i can find where the problem is in the class 2 serial port

 

Did you ever figure out what was 'wrong' with the communication link to your car? I have a 2001 Suburban that will not link to my AUTEL 900BT. On the OBD2 port, data is alive on Pin 2, grounds are good on pins 4 & 5. Power on pin 16. I do not see any data on pin 14. As noted elsewhere, the 2001 did not have CAN yet, so pin 14 should be used for J1850 PWM (Pulse Width Modulation), 0V on idle, 5V when data is transmitted.

There must be some setting for the AUTEL to tell it that it is hooked up to a pre-CAN car????