Passenger side floor leak

[benelli]

Ok so I’ve been chasing this down for a few days. 2017 GMC SIERRA Some suggested remove the fender and reseall the wiring harness. No need your leak is from the plastic cover under the windshield cowl. There are 2 issues . # 1 if you remove the windshield cowl you will notice on the far right of the vehicle under the cowl there is a plastic cover painted same as vehicle. It’s sealed with crappy sealant . If you lift the edge with you fingernail you will

notice it’s not sealing lifting up. Water trickles down that edge of the plastic plate and falls into the fresh air plastic duct in turn flowing down to the heater motor passed the cabin air filter. Under the dash of your truck there is a plastic pan like cover covering the heater motor wires . It also has a piece of thin white insulation for sound detening. If you just pull down on the plastic pan cover abit you will see the insulation it’s white and stained with water even abit reddish in the edges. That’s were the water pools and when you drive off the water will slosh forward or back either wetting to of carpet or fall behind the rubber firewall padding . This is were the underlay will soak up the water like a sponge. Anyway resell that plastic cover with RTV . And also replace the foam seal with a rubber one underneath the windshield shroud. Last 3 days of hard rain no leaks. I’ll try to load some

Pics.

Edited April 5, 2023 by benelli

[rav3]

Interesting. I'll keep this fix in my diy library! Thanks for sharing. 

[Redsilverado831]

Hello,  I am having the same issue with the passenger side floor being soaked after a rain. I've looked over many forums and have seen your fix before. My issue is being the removal of the cowl itself. Do you have any information on how to remove properly and safely with out breaking anything? 

[PFTX_5.3]

2 hours ago, Redsilverado831 said:

Hello,  I am having the same issue with the passenger side floor being soaked after a rain. I've looked over many forums and have seen your fix before. My issue is being the removal of the cowl itself. Do you have any information on how to remove properly and safely with out breaking anything? 

I've never taken mine off but I assume it's clipped in. GM really likes to use clips that don't have a release, you have to give them a firm yank straight up from the clip. It will feel like you're about to break them, and then, POP, they release. Before you do that, remove the pins with the 5 on the diagram, the clip tool makes this a whole lot easier but you can also pry them out with a flathead.

[UrbanRage]

The hardest part about removing the cowl was getting the wiper arms off. 

[dna9656]

Are you guys sure it isn't a clogged sunroof drain? Anyone ever replace a sunroof drain?