Airbag Light | 1996 Pontiac Grand Am | No Communication

No Airbag Module Communication – 1996 Pontiac Grand Am

This will be a quick and to the point case study. This 1996 Pontiac Grand Am came to us with the air bag lamp on. First thing I did was went and scanned for codes with my Tech 2. When I tried to retrieve information from the air bag module, I got the dreaded No Communication message.

No communication problems with any module is usually pretty simple to diagnose. The problem will usually either be a power supply issue, ground issue, data line problem, shorted reference voltage issue, or a bad module. First thing I check are the fuses that feed the module that is not responding. If all the fuses are good, I will try to communicate with any other modules in the vehicle. If ok, I will then go directly to the module not communicating and check all of the power supplies and grounds to that module. If there is no problems found there, I will check and make sure the reference voltage is not shorted out. I then also make sure the data line is good back to the dlc and that it is not shorted to power or ground. If I still see no problems, I will check the module connections and then replace the module.

On the this Grand Am, the fuses for the air bag module were good, so my next step took me to the module itself. As with a lot of GM air bag modules, this one was located under the carpet, under the passenger seat. As I was pulling up the carpet, after removing the passenger seat, I was reminded of the 1992 Cadillac Eldorado and it’s frozen carpet. The carpet was frozen on this Pontiac as well and there was actually chunks of ice next to the air bag module. Water damage and corrosion were the cause of the no communication problem on this one.

In the pictures you can see the ice chunk, corrosion under the module, and corroded connector and module pins.

Leave any questions or comments below. Thank you.

Automotive Diagnostic Scope Training ManualThe Automotive Scan Tool, Scope, and Waveform Training Manual is just over 40 COLOR pages long and is full of images, tests, information, tables, conversions, and common problems. This manual is focused on advanced beginners and intermediate users. Advanced users would also find this manual very handy. The main focus of the manual is on scope usage, interpreting waveforms, and utilizing your graphing scan tool(s).

Great guide for Snap-On Modis, Versus, and Vantage Pro users but the manual is designed for all automotive scopes in mind. This great resource includes useful charts and tables, scope waveforms, graphing scan tool testing tips and tricks, along with scope test lead and low amp probe test hook up location diagrams. Sensor tests include O2, TPS, VSS, MAF, CKP, CMP and MAP. Other component testing includes fuel pumps, coils, starters, blower motors, and fuel injectors. Ford Mode 6 misfire diagnostics and Ford coil on plug (COP) testing tricks included. Tricks include two test lead hook-ups to diagnose how many coils and which cylinder coils are bad, even before the customer knows! Download Now – $15

Comments (6)

  1. Good, logical approach! No communication issues are often followed by lots of guessing, rather than standing back and considering the possibilities. How does the thing work? If you don’t know how; don’t guess, or start out on a parts shopping spree. Identify the all the components; understand their function; how they interrelate, and how they could, do, or don’t contribute to the problem. Every wire has two ends. Dynamic testing beats static testing. And volts drops find high resistances, which on modern véhicules are less and less tolerated by control units; giving rise to countless problems, which are often not shown by static tests. Resistance testing alone is futile in circuit wiring tests as it doesn’t prove that the circuit can carry the load required to operate the consumer: only that the circuit is complete – or not! Understand; consider; test; confirm – and do clear codes where appropriate, when finished!!

    Your articles are much appreciated. We’ve all struggled in our quest to find a problem, but it’s clear that understanding the workings, and following the basic rules is the only way to go!

  2. Richard

    I have the same car with the same problem. My question is this. If I replace the module myself with one from a car that has nt been wrecked is there any chance of it wrking without having to be reprogrammed frm the dealership?

    • Travis Dewitz

      It will need to be programmed and a new BCM may also be needed to successfully program it (normally 2000’s and up).

  3. Michael

    Thanks for the GM air bag module tip, no other source even directed me to its location will ck all connections now that I know where it is

  4. Terry

    I have a 99 cav convertible that has same problem, corded module.Can you tell me how to unplug the connection, haven’t been able too. The grey plug on top of yellow connector came out, wire attached to side round grey piece is still in yellow connector. But yellow connector won’t unplug. Thanks for you’re help.

Leave a Reply

Your email address will not be published. Required fields are marked *

Get in touch with me!

Don't hesitate to contact me for any automotive module programming or diagnostic testing.