There is a ground underneath the pass seat. It's under the carpet and held down by a 10mm bolt I believe..... I would check that next........
Unfortunately, without spending the cash to diagnose it at the dealer, you'll have to put in the time and wrench work to check each of the connections going to the module.
I can't overstate enough that google and this site will be your best friends!!! I won't clog the site with reposts but there are tons of pics and step by steps posted on both to walk you through checking all the connections, their locations, the grounds and the module itself.
I can tell you with 99% confidence, your problem is in one of 3 places...
1) The connections under the seats are lose or have a crimped or broken wire/connector.
2) The ground is lose/broken somewhere.
3) Or a bad module
I'd check in that order... If you eliminate the first 2, you know the answer.....
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