Hello corvette forum,
I have been a long time lurker and now a new poster. I have searched high and low on this topic and have run into nothing but dead ends. Here is my issue.
Anyone in here ever had an obd port issue causing SAH and STC to come on. This just started happening this past week. I have been able to recreate the error messages by plugging in either a scanner or a dashlogic into the obd port and the messages pop up immediately if the car is running. It will keep me from connecting my scanner until I unplug from the OBD, shut the car down, open my door, and restart the car. Error codes u2105 and u2107. Lost comm with ecm and lost com with bcm. Any insight is greatly appreciated. I have no idea how to fix this as I would like to continue to run my Dashlogic as it is very helpful in monitoring my car. Thank you in advance.

 

Get a can of CRC electrical contact spray cleaner and start by spraying out the OBD II pin connectors on the cars port connector channels to clean up any corrosion/ build to the port connectors.
Note, put a towel on the carpet mat under the plug to catch the spray drips.




Next, break out some dielectric grease to push into the OBD II pin channels, and work your scanner plug in and out of the port a few times to migrate the grease to the connectors in the OBD II port channels.

Hence just ran into the same problem a few weeks ago on another guys vet giving him a hand, were my tech II was dropping communication out left and right, until I did the above to get a good connection to the OBD II connectors to solve the dropped communication problem.

Also to point out, if you have the car tuned, and someone lock the tune, they locked you out of the BCM as well. Hence you should be able to pull the standard codes with say a Elm327, or standard cani scanner, but with the ECM locked, it pretty much lock you out of the BCM instead.

If the tune is locked, and you can't get the tuner to unlock the tune, then it becomes a hassle to solve the problem. Hence you need to send the ECM off to have it unlocked to begin with, then reflashed with the OEM tune again to start, then can have someone else retune the car, but this time not locking the tune isntead.

If you have a question if the tune is locked or not, find someone with a Tech II after you clean/grease the OBD II pins, and see if they can access the car with the tech II.

 

I've had this happen before and it seemed to be due to the OBD port not liking the cable I was plugging in.

I originally had purchased an extension cable with a hard bend in it so that I wouldn't run the risk of knocking it out with my foot at the track. It worked fine for the longest time but then all of a sudden it started throwing those same codes totally out of the blue.

I ended up going back with the original cable from my HP Tuners interface and haven't had a problem since.

 

Thank you very much. I will try the above and speak with my tuner. Are there any grounds or wires I should check that may have come loose while I am in that area. Going to do the comb on the steering column while I have the under dash apart.

 

The OBDII port is a direct wire shot to the BCM, so if you think that you have any wires that are grounded out between the two, should be able to find such easy enough.

Also as noted, try another scanner, to make sure that the problem is not a grounding problem in the scanner cord isntead.