I bought a 2004 Gx470 last week, it has 200k miles, one owner, lots of maintenance records. All I’ve done is wheels and tires, and some lighting stuff and removing the steps, nothing serious but I’ve been really enjoying it. Earlier today, I was driving about 40mph, and the traction control light started flashing, and there was an intermittent beeping. The truck drove fine for a few minutes while it was doing this, but then it randomly started applying the brakes to what felt like the front right caliper and the brake pedal was kind of pulsing almost like abs was engaging. I checked my brake fluid and it was near the max line. I will scan with techstream later, is there anything I should be checking for? I’ve read a few people talking about rebuilding the master cylinder or replacing the abs pump. I know techstream will give me a better idea of what needs to be done but I was just wanting to see if anyone had some insight before I get the chance to do that.
GX470 randomly applying brakes (1 Viewer)
- Thread starter SynergyGreenSS
- Start date
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I just completed a repair for a very similar issue (ABS engaging randomly while under normal braking. Even at slow speeds. No lights or codes) on my 2nd generation Tundra. After reading lots of forum posts about unsuccessful (and costly) ABS pump, brake booster, wheel sensor and master cylinder replacements, I stumbled onto a diagnosis of a failing hub bearing.
Hooked up to techstream and followed the wheel sensor test. Sure enough, my L/R sensor was giving an inconsistent reading. The wheel sensor was giving a reading, so I treated it as good and focused on the wheel bearing. Ta-da! Metal flakes and a pretty bad wobble on the axle. It was NOT detectable while installed, only after pulling the axle. Replaced with a Dorman pre-assembled bearing and axle and it fixed everything. It has to do with debris and wobble interfereing with the ABS tone ring and sensor. Yes, it was a Tundra, but I've learned over time that the boys at Toyota use the same tech across platforms and years....
- Thread starter
- #3
Thanks for the response, I’ll try that test in techstream and see what it tells me. I’d love for it to be something somewhat simple like that. Not sure if this has any impact on your suggestions, but in my situation the brakes are grabbing and and sounds/feels like ABS engaging when I am NOT touching the brake. Regardless, I’ll try that test on techstream and see what the outcome is. When you say inconsistent reading, what do you mean more specifically?
My issue was always while braking.
The techstream test grabbed a wheel speed freeze frame at some point while driving...techstream said "follow the FSM test procedure" well, I don't have one, so I clicked continue and just drove her around the block. The results showed a freeze frame reading that showed 3 wheels at 18mph and the L/R at 7mph....Busted!
I have overactive VSC when cornering with my 05. Found out it is rear right rear bearing. I pulled the wheel sensor and it got slight groove on it.
Pull the rear axle shaft and can feel the slight looseness. Cannot feel any movement with the axle fully seated.
The front nearing are new. Rear bearing are about $313-350 each from dealer. It also need special tools to remove it.
Pull the rear axle shaft and can feel the slight looseness. Cannot feel any movement with the axle fully seated.
The front nearing are new. Rear bearing are about $313-350 each from dealer. It also need special tools to remove it.
- Thread starter
- #6
I did a datalog with techstream and all of my wheel speed sensors seemed to be reading properly. After the drive when the light was blinking and beeping, and the brakes were randomly engaging, I have not had any of that happen since. There’s obviously an underlying issue I’d like to sort out as opposed to just ignoring this. I’ll be checking all the hubs and bearings this weekend
