Q: Trackpad on mac book is going crazy!

There are several possible causes for this issue. Take each of the following steps until it's resolved.

1. Follow the instructions in this support article.

2. Open the Bluetooth preference pane in System Preferences and check for unknown or forgotten input devices. Disconnect any USB input devices that you aren't using.

3. Boot in safe mode and test, preferably without launching any third-party applications. If you don't have the problem in safe mode, but it comes back when you reboot as usual, stop here and post your results. If you can't boot in safe mode, do the same. If you booted in safe mode and there was no change, go on to the next step.

4. Reset the System Management Controller.

5. If you're using a Bluetooth trackpad, investigate potential sources of interference, including USB 3 devices.

6. A swollen battery in a MacBook Pro or Air can impinge on the trackpad from below and cause erratic behavior. If you have trouble clicking the trackpad, this is likely the reason. The battery must be replaced without delay.

7. There's a report that a (possibly defective) Thunderbolt Ethernet adapter can cause the built-in trackpad of a MacBook to  behave erratically. If you're using such an adapter, disconnect it and test.

8. There's also a report of erratic cursor movements caused by an external display that was connected but not turned on.

9. If none of the above applies, or if you have another reason to think that your computer is being remotely controlled, remove it from the network by turning off Wi-Fi (or your Wi-Fi access point), disconnecting from a Bluetooth network link, and unplugging the Ethernet cable or USB modem, whichever is applicable. If the cursor movements stop at once, you should suspect an intrusion.

10. Make a "Genius" appointment at an Apple Store to have the machine and/or external trackpad tested.

I had this today (good set of points above by the way).

Basically I'm sat in a cafe and realised that a little drop of water from my cold drink had got on the track pad and found its way into the edge inside.

Simple fix, get a thin piece of paper, preferrably a receipt, get a corner edge and slide it in the gap between the trackpad and the Macbook body. slide it along each side of the trackpad using a new corner of the receipt paper for each. If there is any damp or droplet, it will soak into the receipt. Just did this and there was a small amount on the one side of the trackpad. Working completely fine now.

Symptoms for me was pointer jumping horizontally across the screen, probably due to the location of the droplet, and loss of control using the trackpad, kind of fights you.

I concur! This was totally it for me! i was drinking a cool beverage as well, and sweat from the bottom of my glass dripped into the trackpad.... thanks for the info!

I did as suggested, and about 10 minutes later, it was working fine again....

I just had a similar problem caused by a spot of my daughters hairspray on the trackpad. It is hard to see on the trackpad, but shows up easily on the black keys. If it is on the keys, it is on the trackpad. Clean the trackpad.

If you have a USB or Bluetooth Mouse, you can disable the trackpad by going to Universal Access, click on "Mouse and Trackpad"; "trackpad options" and then the "ignore buildt in trackpad when mouse or wireless trackpad is present" checkbox.  That will stop all the erratic involuntary movement.

My MacBook Pro has had this problem off and on and I accidentally discovered a way to "cure" it. When the cursor starts getting erratic, I quickly close the cover of my MacBook and wait a little. When I open it again, the cursor has usually calmed down, at least for a minute. Sometimes I have to do this over and over for several days, and then it finally stops. This last time it happened, it stopped in much less time than it had before. It takes patience, but it works, and you don't need to call a technician.

jazzrascal:

This is excessively bad advice! What you are recommending really just amounts to ignoring the symptoms and hoping that the problem goes away. If this is being caused by a swollen battery, ignoring it could result in permanent damage to the computer. If it is actually being caused by someone accessing the computer remotely, ignoring it gives them more opportunities to do something malicious.

Please stop posting this advice everywhere!

I had this problem twice now....very frustrating but ended up having to take it in to be looked at.  Technician says there was a build up of static on my track pad and that if you plug in the power adapter and have the user grouned (feet on a hard surface floor) then the user will absorb the extra static and solve the problem.

Mine is home and working great now so thought I would share that solution at least as something for people to try

Apple didn't know that.  They thought there was something wrong with the hardware

Same thing just happened to me and I'm a freelance graphic designer on deadline! I just now took out my battery and it works fine. Whew!!! Swollen/bad battery apparently.

That little sticker (pictured) was sitting flush against the center bus on the trackpad chip. If a little drop of liquid gets in along the top of the trackpad, it can travel down the ribbon and to sticker. Add a little heat from the adjacent battery and its ink can be deposited onto the bus.

As I'm sure you've now guessed, this is what happened to me. It seemed to be causing an interference along the top of the trackpad [visible in the 'Show Live View' feature of Better Touch Tool (Freeware)].

I suspected a swollen battery, but mine was fine. The part of the battery that sits beneath the trackpad is encased in fairly thick battery. I would be skeptical of anyone telling you its a swollen battery without you inspecting it. Removing the battery may just lower the temperature in that area, masking the symptoms.

I removed the whole ribbon cable from its ZIF connector and peeled off the stickers and took a cotton swab dampened by rubbing alcohol and swabbed the ink off the bus. The first few swabs were dark when I was finished. Its been over a week now, and my previously unusable computer has not had even a momentary relapse.

PRAM and SMC resets would only give me a few minutes of respite before a resurgence. If you are going to pay to fix, you need only buy the ribbon cable and chip.

Temporary quick fix: disable trackpad in settings and use a USB mouse.

Attached: The underside of the trackpad with the user side of the computer up, trackpad ribbon cable removed.

My Macbook started doing the very same thing just now. The bottom cover has been deteriorating and is now a twisted piece of unsightly plastic. It has seriously expanded out of the screws that hold it in place.

So back to the trackpad...it would not respond properly (the book is almost three years old), I accidentally unpluged it and it started working just fine. So I plugged it back in and the erratic response started up again. Could this be a new glitch?

If you have a white MacBook with a deformed rubberized bottom cover, take it to an Apple store and have it replaced (free):

https://www.apple.com/support/macbook-bottomcase/

Linc's advice (above) for trackpad issues is about as comphresive as it gets. Moisture, hand lotions, and built-up static electricity are all common causes of erratic trackpad operation and easily solved.

Thank you Motorcycle Michael.

My pleasure!