Second Generation Nissan Xterra Forums banner
1 - 20 of 20 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
This problem is driving me nuts and is potentially very dangerous. I've been searching NEWX and other sites for months and can't find anyone experiencing exactly the same symptoms, so I'm throwing this out to the group for "HELP!"

I have a second hand 2010 xTerra with 80K miles, purchased about 6 months ago. It is rock-stock, standard size tire & wheels, no mods. I live off-road in a very rural part of Hawaii so I drive both paved roads and some pretty serious mud & gravel tracks every day.

The brakes & ABS work perfectly 99.5% of the time. The problem is that once out of every few hundred times that I press the brake, the pedal sinks almost all the way to the floor before the brakes engage. Normal braking doesn't return until I have exercised the ABS by forcing a skid.

All of the brake pads and discs look perfect. There are NO warning lights or OBD codes thrown. The problem occurs in both 2x4 & 4x4 HI modes. Turning VDC off has no effect. The truck drives and stops perfectly except for these very rare occasions.

For the first few months these failures occurred only "off road" where I was driving slow anyway and it was no danger. I always still have brakes, they just don't catch where expected in pedal travel, and brake control is poor because there is only 1/2" pedal travel between "no braking" and "full lockup".

But last week this happened at a stoplight on the hiway, which was scary and dangerous...

Carfax showed me that the previous owners had done "brake service" and a brake bleed shortly before they sold the vehicle. Also the master cyclinder and ABS control unit both are very clean and look as if they may be new (or used refurb). I very much suspect that this brake problem was why the previous owners sold it, after maybe throwing hundreds of dollars away on attempted repair.

Threads here might suggest doing another complete brake fluid flush, but the fact that it appears this has already been done very recently, plus the possibility that the master & ABS actuator have already been replaced, and also the fact that the problem appears so rarely (once a month or less during regular daily use), leads me believe that this might be wasted effort and cost.

I'm thinking of disabling ABS just to make sure that it is the root of the problem. All references here recommend "pull the ABS fuse" to do this, but the service manual shows 3x separate fuses for the 2010 ABS, all under the hood:

Fuse # / fuse size:
L (30amp)
N (40amp)
50 (10amp)

Under the Service Manual section for troubleshooting ABS, they say to just unplug the harness at the ABS actuator module to disable it for testing.

So- three questions:

1) Has anyone experienced exactly my problem (extremely rare "pedal to the floor", OK otherwise)

2) For disabling ABS- unplug ABS module or pull fuse? (and which fuse?)

3) Any other suggestions, particularly if you have experienced and FIXED it?

MAHALO! for any help!
 

·
Registered
Joined
·
2,769 Posts
Your first best step is likely to get a code reader that will read ABS codes and see if you have any. There are a lot of sensors that input into the ABS - more complex than you would think - wheel speed sensors, steering angle sensor, G sensor. Throwing parts at it is likely the long way around.
 

·
Registered
‘06 Super Black S 5AT & ‘10 Knight Armor OR 5AT
Joined
·
1,237 Posts
I agree with @Brunnie , get the brakes bled again properly. I’d even suggest taking it to the dealer to do it if you don’t bleed them yourself.
My gut says there’s a teensy bit of air that’s causing the bad behavior.

NEVER trust what work might have been done prior to your buying a used vehicle. If something is suspect it’s always best to start fresh. That way you know for certain it was done the way you want it, to your satisfaction, and proper.
New parts doesn’t mean that a problem is fixed. Hell, the new parts could BE the problem.

Start small and cheap. Work up from there. Do the bleed first.
(You’ll pay a few extra bucks at the dealer, but maybe it’s best they do it and check the system for you.)
It’s been awhile, but did you holler at the dealer you bought it from? They might help with cost. Any warranty?
 
  • Like
Reactions: mtnbound

·
Registered
2013 Pro4X, 6MT
Joined
·
1,253 Posts
I've never experienced those particular symptoms on my X (or any car I've owned).
Not sure about how to disable ABS but ...
If it were me I'd take the advice above. It's possible they replaced brake system parts, unrelated to this problem, and never got a proper bleed . I would definitely start there as it is easy to do and won't cost anything if you do it yourself.
Good 'help requested' post, BTW. Lots of background clearly communicated. Don't always see that here.:) Good luck getting to the bottom of it.
 

·
Registered
2013 Xterra Pro4X 6spd
Joined
·
120 Posts
[email protected] what island you from. I'm on Oahu.

As stated by others, I would flush the brake fluid. I got mines last year jan. Its a 2013 with 35k mi. It looked like the previous owner wheeled in it so changed ALL my fluid just incase. I would start there.

The brake flush procedure was different than the previous Toyota I had. Hopefully another member can let u know what tire to start.

Aloha
 

·
Registered
Joined
·
2,393 Posts
Hopefully another member can let u know what tire to start.
From the FSM:
< PERIODIC MAINTENANCE >
BRAKE FLUID
• Do not let brake fluid splash on the painted surfaces of the body. This might damage the paint, so
when splashing it, immediately wipe off the area and wash away with water.
• Before servicing, disconnect ABS actuator and electric unit (control unit) connector or battery negative terminal.
• While bleeding, monitor the master cylinder brake fluid level.
1. Turn ignition switch OFF and disconnect ABS actuator and electric unit (control unit) connector or battery
negative terminal.
2. Connect a vinyl tube to the rear right bleed valve.
3. Fully depress brake pedal 4 to 5 times.
4. With brake pedal depressed, loosen bleed valve to let the air out, and then tighten it immediately.
5. Repeat steps 3 and 4 until no more air comes out.
6. Tighten bleed valve to the specified torque. Refer to BR-34, "Exploded View of Brake Caliper" (front disc
brake), BR-39, "Exploded View of Brake Caliper" (rear disc brake).
7. Perform steps 2 to 6 at each wheel, with master cylinder reservoir tank filled at least half way, bleed air
from the front left, rear left, and front right bleed valve,
---------------------------------------------------------------------------------------------------------------------------

Many of us have also noted that you may have to have the engine running.
But note you start with Right Rear, then Front Left, then Rear Left, then Front Right.

Find a set of Service Manuals online and download them. You will find them to be handy in working on things.
 

·
Registered
Joined
·
170 Posts
Intermittent soft brake pedal without any trouble codes? I had the same issue on another vehicle and the fix was: properly greasing the caliper slide pins. The caliper pins were seized on two calipers.

It's worth a shot to check and an inexpensive fix. My symptoms also occurred after a recent brake service that obviously wasn't performed properly. It was a $100 fix versus the $1,100 fix for a new ABS unit and other things one guy wanted to throw at it.
 

·
Registered
Joined
·
55 Posts
I've successfully done a gravity bleed on my X, although never from a dry condition. Only flowing fresh fluid in place of old. The FSM doesn't say anything about activating the ABS in order to clear air, so any standard bleeding procedure should work.

Are you losing fluid anywhere? Intermittent cylinder seal leaks are rare, but not un-heard of. Is there any sign of fluid loss under the piston dust jackets?
 

·
Registered
Joined
·
55 Posts
Xtra99 makes a good suggestion.

A slider pin that is stuck and cocking the caliper, then suddenly lets go, would leave a void that the piston cylinder needs to fill out.

My X is notoriously bad about with sticking sliders. I would disassemble, clean, and grease them twice a year when swapping snow tires back when it was a daily driver.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #11 ·
Your first best step is likely to get a code reader that will read ABS codes and see if you have any. There are a lot of sensors that input into the ABS - more complex than you would think - wheel speed sensors, steering angle sensor, G sensor. Throwing parts at it is likely the long way around.
THX-
Onnit- Ordering one today (Foxwell NT630 as recommended by other users)
I already have a cheap bluetooth reader that works fine for engine codes, but I'm not seeing anything on it- maybe it can't receive ABS codes?
Note again though that I am not getting any MIL's, so dunno if any codes are being thrown at all...
I'll report back if I see anything with the new scanner
Mahalo!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #12 ·
Intermittent soft brake pedal without any trouble codes? I had the same issue on another vehicle and the fix was: properly greasing the caliper slide pins. The caliper pins were seized on two calipers.

It's worth a shot to check and an inexpensive fix. My symptoms also occurred after a recent brake service that obviously wasn't performed properly. It was a $100 fix versus the $1,100 fix for a new ABS unit and other things one guy wanted to throw at it.
Yah I thought about that, but I'm not experiencing any pulling or uneven braking under any circumstances, ever... if I had frozen sliders or a stuck caliper piston I would expect to feel some "pull" during non-ABS braking?

That said, it is true I haven't actually visually checked for this. Good tip.

(you guys are wonderful! thanks for all the well thought help!)

(PS: I'm on Hawaii Island wet windward side, out in the boonies off-road and off-power)
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #13 ·
I've successfully done a gravity bleed on my X, although never from a dry condition. Only flowing fresh fluid in place of old. The FSM doesn't say anything about activating the ABS in order to clear air, so any standard bleeding procedure should work.

Are you losing fluid anywhere? Intermittent cylinder seal leaks are rare, but not un-heard of. Is there any sign of fluid loss under the piston dust jackets?
Nope, no fluid loss
In fact, the master was slightly over filled (above the line) when I bought the X, and the level is still right there 6mo later.
I'm not enthusiastic about trying to flush an ABS system by myself (I've had enough trouble with non-ABS flushes!), so I will probably have it done at a shop.
Mahalo!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #14 ·
UPDATE 4/23/2021:

I received my Foxwell NT630 Plus, registered it to my vehicle, and verified that ABS control functions work (I was able to activate ie the RF wheel ABS sensor with very clear & noisy results).

There were no fault codes registered, either DTI or ABS.

My brake problem only occurs once every few hundred times I use the brakes (maybe once or twice a month), so maybe any "Pending Codes" have been automatically cleared- I dunno.

In the absence of any recorded error codes, I really don't know how to effectively use this tool to troubleshoot my problem- Any help on that from an experienced investigator is more than welcome!

I have not yet done a full brake fluid flush- I've done this in the past successfully on non-ABS vehicles, but at 70yrs old with limited available work space, I am going to leave this to a service center when I can get to it. It would be nice if I could get some guidance from this scan tool about whether trapped air is my problem. Again- any guidance is welcome.

In the meantime, I am disabling ABS by following the forum instructions here:


I frankly think I can live without ABS or VDC, but I'm not sure that I will survive a random and unexpected "pedal to the floor" incident during an urgent stop situation.

I'll update again here if I find that disabling ABS does NOT solve my "pedal to the floor" problem ("hey it's still happening!"), or if a full bleed clearly eliminates the problem (which will take some time as the problem is intermittant at only once every month or two)

Thankyou all for the help & guidance you have provided so far-
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #15 ·
PS: Note that my "pedal to the floor" problem does NOT occur when I am in an emergency ABS braking situation- it happens only occasionally and seemingly randomly during normal gradual braking situations.

So why do I think it may be related to the ABS system? Two things:

1) pumping the brakes even firmly & vigorously has no effect- the pedal still goes to the floor
2) triggering ABS by locking the wheels immediately restores normal brake feel

My feeling is that (1) absolves frozen caliper pads or sliders (maybe?), and (2) firmly implicates the ABS system (probably?)
 

·
Registered
2011 XTerra S Metallic Green
Joined
·
118 Posts
I had same issue with my car. It happened about 5 times over a year. At first I thought I accidentally confused pedals (scared me to death as I thought it might be early sign of dementia or something) then I thought maybe it was glazed (iced up disks). Of cause I read everything on forum but it was just like reading dermatology textbook when you find all possible skin problems on you, ha ha.
So last oil change I took X to mechanic and ask them to do brake flush and had no problem with the brakes since.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #17 ·
I had same issue with my car. It happened about 5 times over a year. At first I thought I accidentally confused pedals (scared me to death as I thought it might be early sign of dementia or something) then I thought maybe it was glazed (iced up disks). Of cause I read everything on forum but it was just like reading dermatology textbook when you find all possible skin problems on you, ha ha.
So last oil change I took X to mechanic and ask them to do brake flush and had no problem with the brakes since.
Good news! Thankyou.

So- have you had several months without a problem since the brake flush?
I haven't had the flush done yet. I did disable ABS last week as previously described, but it's too soon for me to know if this has really made a difference- I was only experiencing a brief failure about once per month.

I'll update again in a month or so...
 

·
Registered
2011 XTerra S Metallic Green
Joined
·
118 Posts
Good news! Thankyou.

So- have you had several months without a problem since the brake flush?
I haven't had the flush done yet. I did disable ABS last week as previously described, but it's too soon for me to know if this has really made a difference- I was only experiencing a brief failure about once per month.

I'll update again in a month or so...
I had it done 3 months ago. There haven't been any problems since. Twice it happened kinda intermittently, once on a stop sign and we had 70 miles wind that day. I thought it was wind in my tailgate just when I was moving from accelerator to break. Another time I had to slam break and it felt like pedal went to the floor with no breaking. Then I drove with my son on a snowy day, I always check road conditions how slippery it is and so on, so ABS engaged, breaking and stopping and no sliding on a snow, and when I test second time was same pedal-to-the-floor feel. That when I thought maybe glazed breaks. And last time in January we went skiing, same issue testing breaks on a snowy road. After my testing was no issues rest of the day. I looked through my service records and steelership was recommending break flush 2 years prior . When I asked tech about the break fluid condition after flush was performed he said it was getting dirty. Didn't have break issue since, X drives like a trooper. Hope it helps.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #19 ·
I had it done 3 months ago. There haven't been any problems since. Twice it happened kinda intermittently, once on a stop sign and we had 70 miles wind that day. I thought it was wind in my tailgate just when I was moving from accelerator to break. Another time I had to slam break and it felt like pedal went to the floor with no breaking. Then I drove with my son on a snowy day, I always check road conditions how slippery it is and so on, so ABS engaged, breaking and stopping and no sliding on a snow, and when I test second time was same pedal-to-the-floor feel. That when I thought maybe glazed breaks. And last time in January we went skiing, same issue testing breaks on a snowy road. After my testing was no issues rest of the day. I looked through my service records and steelership was recommending break flush 2 years prior . When I asked tech about the break fluid condition after flush was performed he said it was getting dirty. Didn't have break issue since, X drives like a trooper. Hope it helps.
Yes your experience sounds much like mine, except mine was more frequent (1x - 2x per month). And 95% of my problems occured "off road" (dirt/gravel), only once so far on paved roads.

I'll be doing the brake flush sometime in the next couple months for sure, but for now I'm testing the "disable ABS" theory...

Aloha!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #20 ·
Update 5/26/21:

It's now been well over a month since I disabled ABS, and no new "Pedal to the floor" incidents. Not incontrovertible proof, but it certainly does look like this workaround eliminates the problem, though at the cost of giving up ABS, VDC, and anti-slip.

This workaround actually does not disconnect ABS directly- it only disconnects the Yaw sensor, and the computer disables ABS as a result. This leads me to wonder whether maybe it is the yaw sensor that was actually at fault in the first place? I think it's a possibility.

I still haven't got around to doing the brake flush though, so the jury is still out on that.

I'm a big fan of ABS when it works, but not at the risk of experiencing these rare but very scary and hazardous "pedal to the floor" events!

I've had ABS on two previous Toyota's (4Runner & Tacoma), and never experienced anything like this, even after changing brake pads and performing brake bleeds. Considering how dangerous this problem could be, I'm surprised there is not a lot more chatter & information about it (or a factory recall??)
 
1 - 20 of 20 Posts
Top