My 2014 XJ Supercharged with 73 thousand has developed a loud squeak somewhere inside the dash when driving over the washboard roads here. I have not been able to determine where the squeak is coming from. I am thinking that I will have to start by removing the glove box for access. Anyone had their dash apart? How is the dashboard attached?

 

If you have a helper, you can make a stethoscope from a funnel and a piece of 1/2" rubber tube... attach the funnel to one end of the tube and hold the other end to your ear, and move the funnel around while your helper drives the car. As the funnel gets closer to the source of the sound, the noise coming from the tube will get louder and you'll get a better idea of where the sound is coming from. If you don't have a helper you can tape the funnel in different positions, but you have to stop to move it which is a bit of a pain.

There's plenty of other ways to do this including this awesome kit from "Steelman" (https://steelmantools.com/products/w...tic-device-kit) but the funnel and fuel line trick works great for one-off jobs on a budget

 

The first things to check are the front shock mounts.
Open the hood & bounce the front of the car as much as you can.
Listen for the squeak and look for movement at the top bolts that secure the top of the front shocks into the mounts on the shock towers.
It's been posted about quite a bit in this forum, and usually the sound that seems to come from the dash really comes from under the hood.
The foam isolators of the shock mount wear out & fall apart, and the metal begins to rub producing the squeak.

More about it in this post:
Squeaky Squealing chirping under dashboard - Jaguar Forums - Jaguar Enthusiasts Forum

 

Another vote for the upper strut mounts. It's amazing how much that sounds like it's in the dash and if not for this forum that's where I would have started too!
It's not a hard repair and no front end alignment needs to be done afterwards either.

One tip I did NOT follow is to make the lower A arm easier to pry down so you can remove the entire strut assembly. Disconnect the sway bar end links! Simple and effective!
On the bench you will need to compress the spring to replace the top mount.
.
.
.

 

I read another thread "Squeaky Squealing chirping under the dashboard" dated 11-25-2018 started by vas sinyuk about his 2011 having the same issue and referenced in this thread by 12jagmark. Discussions covered everything from removing the entire dash to deterioration of the upper shock mount C2D51875 and top bearing C2D16903. Although skeptical, I soaked the top of both shocks with Kano Aerokroil. I did not see immediate results, but after soaking overnight, the squeaking was gone. Closer inspection of the top of the shocks revealed that the right side, in particular, was no longer centered.

So, now to order the upper shock mount and top bearing for both sides.

Thanks for the tips about the shock mounts. I was afraid I was going to have to tear out the dash.

 

Yep those bits of red crumbs are the tell tale signs of a worn out upper strut mount.
I think you will be pleased when you get them changed out.
.
.
.