Skip to main content

Should we assume nobody told GM that mixing electricity with water is a bad idea? We’re kidding, but the National Highway Traffic Safety Administration isn’t. It just issues a Technical Service Bulletin about water getting into parts of the GMC Hummer EV it shouldn’t be. It says that leakage around the windshield of Hummers is causing terminals of certain connections to corrode. The NHTSA calls out two areas where Hummer windshield seals aren’t sealing. 

What GMC Hummer functions are affected?

GMC Hummer EV in the Desert
GMC Hummer EV in the Desert | GMC

Leaks are being found around the driver’s side A-pillar and the lower center of the windshield. The water then travels down the door jam to the connector for the door. If corroded, it affects the operation of the driver’s side window, mirrors, and door locks. Essentially, all of the powered functions that are in the door.

Either the seal is failing, or it is improperly made. This is based on close-up images supplied by the NHTSA. If there is leakage, the service bulletin says to replace the connector in the door and reseal the leaking area. Then test for leaks to make sure the seal is working.

Have there been other GMC Hummer issues?

A white GMC Hummer EV pickup truck model speeding down a country highway
GMC Hummer EV | GMC

These types of things do happen. But in recent years it almost seems like buyers become Beta testers for early models. There have been two recalls of the 2022 GMC Hummer since production began earlier this year. For a vehicle costing over $100,000, it isn’t a good situation or good optics.

GM is leaning in hard to be the EV leader. But it has had problems with most of its all-electric models like the Chevrolet Bolt. It was hoped that with the Hummer riding on GM’s Optium electric platform, there had been enough time in development to ward off these types of quality issues.

What about recalls?

GMC Hummer EV Edition 1 Commemorative Plaque
GMC Hummer EV Edition 1 Commemorative Plaque | GMC

The first Hummer recall was a minor one. Especially since it only affected 10 of the SUV. It was a software issue that caused parking or running lights to either go dark or stay permanently lit. Because the single light operates so many functions, it could cause issues with multiple lights. These include lights for the brakes, turn signals, reversing, the side marker light, and the clearance light. 

The next recall earlier this month affected 424 Hummers. GMC is not producing a lot of these trucks, so even though the number of affected units seems low, it represents most of the production of the EV thus far. Because this issue didn’t involve safety, as the previous one did, this was a voluntary, not mandatory, recall. 

This was also for water leaks, with the issue being water getting into a high-voltage battery connector. If that happens, it corrodes the battery connector. The sealant applied to the connectors should solve the problem. Because this was a voluntary recall campaign, it doesn’t always show up in recall lists. However, plugging your Hummer VIN into the GMC Recall Center website will verify if your SUV is part of this issue or not.


As Used Car Prices Surge It Might Be Time to Invest in Car Maintenance