Hey y'all.

I hope someone can shed some light on a problem we recently started experiencing with my 07 V8 4runner. The first time it happened was last October after a 100 mile trip. We parked at the hotel and the next morning when I started rolling in reverse, it felt and sounded like a wheel locked up.. I stopped immediately and checked because it sounded like I was dragging a boulder or something. I then had no other trouble and drove the rest of the day and home. After this, occasionally when we shift in to reverse and start moving, it feels like the brakes lock up. just for a second and as soon as I step on the brake and release, there's no problem. It never happens when driving forward.

I should add, I am also experiencing a spongy brake issue. The first press of a drive almost bottoms out. The truck stops and after that press, the pedal feels better although still spongy. I do not have any lights showing up on the dash nor do I have any fading at a very long red light. I am pretty accustomed to the spongy feel however my wife is not and feels unsafe. Admittedly, that first press is a bit worrisome.

Is it possible that these issues are related to 1 problem or is it likely I have 2 separate issues I need to contend with?

Thanks for any help!

I wonder if it's something as simple as a slightly sticking caliper, or a flexi-hose(s) that are getting tired, expanding and occasionally not returning fluid.

The second issue is weird, I wondered if it was losing vacuum at the booster, but that would be an issue all the time.

Personally I would inspect and grease the caliper pistons, slide pins etc and change the flexi-hoses, then give it a thorough bleeding. It's a fairly quick and easy way of ruling out a few things in a time efficient manner.

I believe someone posted a similar situation regarding the stuck wheel in reverse. It turned out to be the emergency brake getting stuck on one side. I don't recall why it was doing this, possibly an incorrect installation of the pin that holds the brake shoe to the backing plate.

The other issue sounds like air getting in the brake line, or low brake fluid. Since the light isn't coming on I would go with air in the line. Is the brake fluid reservoir low?

I would start by pulling the rear rotors off and inspecting the emergency brakes. These are easily neglected and make for some odd issues if hardware rusts out or the shoes delaminate. Calipers are also a common issue on these, that can for sure make a spongy pedal. Usually the 4 piston front ones fail more than the rears. You can also have a pad hanging up on the caliper that will do the same, this one was my last spongy pedal issue. Luckily, brake parts are pretty cheap and easy to replace.

Thanks for the replies. I have suspected the brake system may be in play. I've done a lot of reading and it seems like this system is pretty finicky. This weekend project is a full system bleed!

The rear brakes are a pain with the parking brake. I had a situation where my axle seals were slowly leaking and then caused various grabbing and releasing at inopportune times. Maybe one day I'll get in and grease the cables from the dash pedal to the rear but I just don't use them ever. I just have to hope if anyone else drives my car, they don't press the pedal when they park.

Has this issue been resolved?

Well, enough time has passed where I can confidently say I have resolved the issues. I did in fact have some air in my brake lines however the main problem was my front inner brake pads were broken in half and essentially disconnected from the backing plate... I have maybe 7500 miles on these pads and rotors so my best guess is the calipers are junk.. When I did the brakes previously, I did replace 1 caliper for sticking and now it looks like maybe I should do both.
I believe the backing up issue is due to the broken pads sliding and jamming against the rotor. I'm not certain but after replacing both rotors and pads under a time crunch, driving back and forth to Maine etc. I have had no issues with the locking up and the brakes feel amazing!

Thanks for the advice!!

strong work amigo, good job.