You’ve got a Macbook Pro and an external monitor, possibly a Dell monitor like mine. Ideally, to use your external monitor with your MacBook lid closed you would merely plug the monitor into the MacBook, close the lid, and the external monitor would light up and you go on your merry way. Maybe this is how it works with a Mac monitor, but it certainly doesn’t work this way with a Dell monitor. To make things tougher, on my MacBook when I go into the display settings and click “detect displays” my Dell monitor doesn’t come up as an option. I can fiddle around with settings all day, and I cannot get my monitor to connect. Reboot while the monitor is connected? Nope. Turn the monitor on and off? Nope. Unplug the monitor from the laptop, reconnect? Nope.
Fortunately, there is a very simple workaround that seems to work every time.
1. Turn on your laptop with the lid open. Your monitor can be connected to it or not, it doesn’t matter.
2. Once your laptop is on, go up to the Apple icon in the upper left corner, and click on “sleep”, or use the keystroke. One way or another, put your laptop to sleep.
3. Connect your external monitor if it’s not already connected. If it is, then skip this step.
4. I assume if you’re using an external monitor with your MacBook lid closed, this also means you’re using an external keyboard and mouse. At this point, tap a key on your keyboard or move your mouse. This will wake your MacBook out of sleep mode, and when it wakes up and the lid is closed, it will immediately detect your external monitor and use it.
Although this is not intuitive, it is rather simple once you get in the habit. The hardest part is just remembering that this is how you do it, especially if you only disconnect your MacBook from your monitor every once in awhile. I recommend putting a sticky note somewhere around where you sit that says “External Monitor – Sleep Mode” or something along those lines so that the next time it happens and you ask yourself “Now how did I fix this last time?” you’ll see the note and remember “Oh yeah, this is easy.”
A few weeks after I wrote this post, my MacBook completely stopped communicating with my monitor. I spent a week researching the matter, and couldn’t figure it out. A lot of other people had the same problem, but nobody seemed to have a solution, at least they certainly didn’t have a solution that worked for me. I was on the verge of buying a new monitor when it occurred to me that perhaps the adapter (which is brand new) might have gone out for one reason or another. I took the monitor and MacBook into an Apple store here in Utah, tried a new adapter, and everything immediately worked. In fact, things worked better than ever. I don’t have to do any of the steps up above, I just plug in the monitor and everything works, lid closed or open, kind of the way you would expect it to.