Considering the breakneck development speed of the new GMC Hummer EV, it's impressive it doesn't have any major issues. There have been a few minor ones so far, though. A few months ago the truck was having problems with its taillights. Now, there are a few more small troubles, one to do with the window and lock switches, and another related to a high-voltage battery connector.
Both of these new problems have to do with water going where it shouldn't, which is a particularly troublesome problem for an off-road vehicle like the Hummer. The first Technical Service Bulletin reported by the NHTSA says that water enters the inside of the vehicle through an improperly sealed area around the driver's side A-pillar. It then leaks onto an electrical connector, which can cause the vehicle's driver's side window, mirror, and lock controls to all malfunction. It also notes that "Some customers may also report unwanted activation of the theft alarm system, or random messages on the DIC such as 'service latch.'" The solution to this issue is to get dealers to replace faulty connectors, inspect for leaks, and reseal the area if they're found.
The second electrical gremlin, rather interestingly, affects not only the Hummer EV but also the Brightdrop EV600, GM's new all-electric delivery van. High-voltage battery connectors can get some moisture in them, which could lead to water entering the battery pack of the vehicle. This is serious, although this defect is being acted on as a Customer Satisfaction Program, which indicates it's not severe enough to warrant a full-fledged recall.
Indeed, the fix for the issue hints that the issue has little to do with the battery itself—don't think we're gonna have another Chevy Bolt-type mass battery pack replacement scheme here. The document states the faulty connectors should be sprayed with some brake cleaner and a little RTV should be added around the connectors to seal them once they're spotless. The document states just 424 vehicles are affected, which gives you a hint as to how many Hummers and Brightdrops have been built.
We've reached out to GMC to see what was being done on the manufacturing front in order to address these issues with the Hummer EV, although we have yet to hear back as of publishing.
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