Mystery hole in fire wall

[MTOJosh]

I have this 1.5 inch hole in my firewall. It looks factory made but the only wire going through there is for the siren on my alarm. I'm going to run a few wires there for my backup camera as part 9f a new stereo install. Does anyone know what this hole is for and if they make something to cover it. An OEM grommet?

 

[Wh4t3v3rs]

I have this 1.5 inch hole in my firewall. It looks factory made but the only wire going through there is for the siren on my alarm. I'm going to run a few wires there for my backup camera as part 9f a new stereo install. Does anyone know what this hole is for and if they make something to cover it. An OEM grommet?

I believe that is where the clutch would come through the firewall if you had a manual transmission. If I remember correctly, there should have been a "factory knock out" there.

 

[mars2878]

You didn't happen to mention the year & model of your truck.
Would it happen to be a Tahoe Limited or Tahoe Z71?
On automatic trucks of this gen, I've only seen that hole on those 2 models.
On those 2 models, that is where the harness for the factory foglights passes through the firewall.

Trying to find body plugs @ the part store, was fruitless for me.
I've had better luck w/ hitting up the local salvage yards.
For the most part, they let me have them for free.

Hope this helps.

 

[MTOJosh]

Sorry folks, I have a 1998 K1500 Truck, automatic, 4wd

 

[Eveready]

Sorry folks, I have a 1998 K1500 Truck, automatic, 4wd

Same cab went into many different trucks There could have been a knockout plug in your truck in the location of the clutch rod. A previous owner likely knocked it out to install a CB radio or some other electric accessory. You might find a plug that size for even another brand of vehicle.. I think my old Dodge van has a pretty big one.

The point is that the fact that you have an automatic is irrelevant as on other trucks that hole might have been used for something. These trucks have had so many owners by now there is no telling what has been done to them.

 

[MIHELA]

That's the clutch hole. I'll find you a part number for a GM plug that fits that hole size later.

 

[MIHELA]

Here's a pic of it installed. 25915587 is the number.