SERVICE AIRBAG SYSTEM LIGHT?

This sounds like the airbag module has gone bad these videos will help us fix it.

https://youtu.be/rTtAnsOlZU4

Please run down this guide and report back.

DTC U0073 72
Control Module Communication Bus Off Alive Counter Incorrect

CIRCUIT/SYSTEM DESCRIPTION
The high speed GMLAN serial data circuits are high speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. The high speed GMLAN serial data circuits also connect directly to the data link connector (DLC).

CONDITIONS FOR RUNNING THE DTC

†Supply voltage to the modules are in the normal operating range.
†The vehicle power mode requires serial data communications.
CONDITIONS FOR SETTING THE DTC
The module setting the DTC has attempted to establish communications on the GMLAN circuits more than 3 times.

ACTION TAKEN WHEN THE DTCS SETS

†The module suspends all message transmission.
†The module uses default values for all parameters received on the serial data circuits.
†The module inhibits the setting of all other communication DTCs.
CONDITIONS FOR CLEARING THE DTC

†A current DTC clears when the malfunction is no longer present.
†A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
DIAGNOSTIC AIDS

†An intermittent condition is likely to be caused by a short on the high speed GMLAN serial data circuits.
†This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom Scan Tool Does Not Communicate with High Speed GMLAN Device to.
†Refer to Data Link References for the specific modules using high speed GMLAN serial data. See: Powertrain ManagementComputers and Control SystemsInformation BusTesting and InspectionInitial Inspection and Diagnostic OverviewData Link References

Please let us know what you find.

Need a scanner to find fault many possibilities which you can get from Amazon for about $30.00. Here is a video to help you see what to do to fix the problem.

https://youtu.be/gnSGfEqrf_w

Here is the scanner

https://www.amazon.com/gp/product/B007XE8C74/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=2carprcom-20&creative=9325&linkCode=as2&creativeASIN=B007XE8C74&linkId=2b1553d47faedf8e31ccd8a7833c6a58

Please run down this guide and report back.

Good morning.

Definitely not the PCM. All the controls you are having issues with are related to the BCM.

Check all the connections on the BCM and see if there are any loose, damaged or burned pins. If that is all okay, then you will need an advanced scan tool to access the BCM and see if there are any fault codes as well as monitoring live data.

It does sound like a failing BCM but need to be confirmed here is video that can show you how

but to be sure lets do a CAN scan which is the future of automotive repair you can get a CAN scanner from Amazon for about $50.00 here is a video to show you how.

https://youtu.be/InIlnsjOVFA

Roy

That test is for a drain, not a short. If you are looking for a drain you measure amp draw, not voltage.

Check you fuses. Pin 16 of the DLC is for power to the scan tool. That circuit is fd from a fuse for the auxiliary power outlets.

You need a real scan tool to monitor the BCM information.

Roy

Yes, that will work as well as a Snap On scan tool as well.

Roy

You are more than welcomed to start a new question with your concern and we would help you as well.

Roy

You are welcome.

We are always glad to help.

Roy

We just had another question on a similar car it was the BCM here are the replacement instructions in the diagrams below.