Was a member here before, but I guess hadn't logged in for a while and got auto-booted. But I'm back again. Anyway, here's the backstory setup:
2020 Denali Ultimate, L87, purchased new
8,800 miles, all original equipment except an Elite Engineering oil catch can.
It finally crept out of its hole and reared its ugly head. It didn't leave me stranded, in fact, it never seemed to exhibit any issues at all. But one day a couple weeks ago, I went to town and on the return trip, a CEL showed up on the dash. WTF? Again, no performance issues to note. With low miles, I figured it was way to soon to have problems.
I have an old Actron 2006 model scan tool that can still read and clear codes on the truck, so I figured wtf. Got a U18A2. That was it. No other DTCs. That's odd. Fuel pump driver module communication loss. Ok. Fuel pump obviously still works. Starts and drives normally. Cleared the CEL, and no more DTCs. What caused the CEL? I dunno. Couldn't just be the U18A2, right? Since then, I check for DTCs after every time I drove it. Got the CEL once more, but U18A2 DTC was the only code that would show up again. No other codes. Really strange. Wasn't familiar with this "problem". I guess it's like anything else, it can fail at any time, any place, anywhere.
Started researching and found it was almost a not "if" but "when" the original module fails situation. Plus, it seems like most discussions said, just replace it basically but never delved into exactly how. Further research left me wondering about reprogramming or configuring the new module. Mixed bag. Some people claimed no, it's plug and play, others say yes, it needs re-configuring. I figured why not try it and if it needs configuring/programming, I'll deal with it later. If not, even better. I never realized there was a national back-order for a while on those, but it seems whatever 40 different part number changes since then seems to have cleared up many module issues. Hope that's the case.
After installation, I drove the truck a few times, no issues so far, and better yet, no DTCs or CEL. Time will tell, and I'm going to jinx myself here, but it seemingly fixed the issue.
For reference, the OEM module was p/n 13531875 and the newest GM p/n as of this writing is 13565641 (which replaced 13558812, which replaced 13540028, which replaced my OEM number 13531875), made in USA. Bought it through Rockauto.com for around $75 shipped. Double check your vehicle for the exact replacement p/n. All truck variations do not use the same module.
And, since the truck is 5 years old, I figured as it ages, stuff will need looked at more via a scan tool, so I ordered up a Launch Tech USA tablet bi-directional with Bluetooth. Crossing fingers, but it seems fairly decent for that price range. I don't need an "everything" scan tool, which it isn't, but it seems it can do a good amount and those that use them seem fairly satisfied.
If it happens to you...Removal/Install Info and tips- First, I disconnected the negative terminal on the battery. I did not want to take a chance on toasting anything unplugging/plugging the connections. On the 2020 crew cab, the fuel pump driver module is located on top of a sheet metal plate, inboard the gas tank about 4 inches below the bed just forward of the differential snout. It uses a claw style pin connector with the red tab lock that needs to be popped up first to get it loose. Then lift up the handle and pop it off the connector. You can barely get a small socket and wrench up in there because the 2 mounting screws need to be accessed from the top. Yay. Kind of a PITA, actually, but not bad. T20 torx bit. That's it. It will come out but you have to contort yourself a bit. I "fixed" that by popping the J nuts off the sheet metal mount and flipped them around and spread them out a bit to fit the flanges on the module. Optional- I then took appropriate sized stainless steel washers just a bit bigger OD than the screw heads and installed the screws from the BOTTOM of the sheetmetal mount. The screw heads are bigger than the pre-extisting holes in the plate, but just barely, hence me using the washers. So, if this ever needs to be done again, I can use my power screwdriver to zip them out quickly from the bottom. Since the OEM module isn't totally dead, I'm going to keep it in the truck under the rear seat along with a T20 torx socket/wrench in the event I DO get stranded on the side of the road over that module. Cheap insurance and it doesn't cost anything. May toss a code, but at least it still lets the pump run if I have to use it in an emergency.
Since I haven't seen recent posts about this, I'm assuming this "issue" has been brought under control now with the newer modules?