Vehicle is a 2005 G500

So I've removed the rear SAM because I've been having some electrical bugs that all seemed to point back to the SAM (tail lights, reverse lights, gas gauge, ABS, SRS, etc.) and had the dealership run a diagnostic test on the car and they confirmed that the front SAM was communicating with the OBD, but not the rear SAM.

So now that I have it removed, what should I do? It seems I can either mail it in to a company like BBA Reman for a rebuild, but there's no guaranty it'll be rebuildable. And I've talked to folks who said they had them "rebuild" it, but still didn't work and had to buy a new one. Do just bite the bullet and buy a new one, but still run the risk that it doesn't solve the problem?

Thanks.

So i split the SAM and this is what I found. I'm not a PCB expert, but could that one solder point that is gunked up be the issue? It looks like moisture may have hit it and you can see somewhat of a splash of something around it. Any feedback would be great. THanks.

That looks like the exact same spot on my SAM . I decided that it was a spot of flux that was not completely cleaned.
But I have some of the same problems . I have no brake lights, tail light only on the rt side and plate light on the rt side
and no side markers. I also have a ABS light. But the ABS is working. No rear turn signals.

I bought a used one on eBay and dropped it in and all is working fine now. Just dropped her off 10 minutes ago at the shop to have the new rear SAM coded to the vehicle. Not sure if theres someone out there who rebuilds these things, but I'm sure a used one is worth at least $150 I would think. I bought my used one for $400.

Do you by chance have a wiring diagram if the rear SAM? I took mine out for repair as well, trying ti get it back in and I can't seem to set out where a few wires go. My pictures are awful I took a bunch to be safe and they are all terrible. LOL.