So as the title implies, I have an ABS issue, and it’s a thinker…
To start, I have no warning lights on the dash whatsoever. I have no performance issues to suggest an obvious problem that needs fixing. My problem is with the traction control system (via the ABS) activating in all sorts of situations where it shouldn’t, and hasn’t before.
If you can imagine, your going down the highway and take an exit ramp, left or right, your choice. You coast from 60ish down to 40ish and take your sweeping exit without touching the brakes or gas and all is good. Now if you were to take the exact same exit, at the exact same speed, but you touch the brakes or gas after you have started turning the steering wheel, that is when I am getting an intermittent SLIP light and I can feel the brake pedal pulsing and hear the ABS actuator under the hood. I’m not talking about a hard press on the brake pedal, or mashing the gas, I’m talking about a normal stead pressure situation. And what’s even stranger is the SLIP light won’t go away until the vehicle is moving in a nice straight line again, regardless of pedal input.
Now for what I have done to attempt to remedy the situation, and thus far failed: First I inspected all of the friction parts. I removed all of the pads and rotors, no problems. Rotors don’t have much runout at all, and pads are about 20% worn so they still have plenty of meat. The parking brake shoes had some caked on mud so I disassembled and cleaned everything. Fresh grease on the contact surfaces and a nice adjustment on the star adjusters and the parking brake is like new.
I checked all of the brake lines, and everything looks good. I did a two person bleed and the fluid wasn’t too dark, but I did get a few very tiny air bubbles from the rear drivers side. I’m suspicious that those bubbles may have been introduced at the bleeder, but either way once they came out no more air followed. In any case, I have new rear stainless lines waiting to go in since my old stainless lines are 5 years old now. I’m just waiting on the front lines to come in. And I went ahead and bought a Motive Products power bleeder and a half gallon of brake fluid so I can flush the whole system. I also ordered new hardlines for the front since they got a little rusty from grinding dust when I did the hydro bumps. All of the lines and bleeding should be done in a week, but I really doubt that will solve my problems.
I also checked all of the calipers to make sure the pistons weren’t frozen, everything moved in and out as it should. I then removed the slide pins and found that the lower slide pin on each corner had a lot of resistance to moving due to swollen rubber. The pads aren’t showing any unusual wear so I don’t think the slide pin problem is doing much right now, but in any case I ordered new lower slide pins for each caliper, those are coming in with the new hardlines next week. I also got the fancy clear 3M silicone based brake paste that Nissan uses from the factory to lube the new slide pins with. I even took the mechanical side one step further and checked the brake pedal free height, and stroke. Both measurements were spot on with factory spec, as they should be since the brake master and pedal assembly have never been touched.
So by now you are probably thinking its an electrical issue, as I was too! I had figured it was electrical anyway since it also happens when you press the accelerator, not just the brake pedal. So here’s the whopper; I replaced both rear wheel speed sensors and the problem is still there! The old sensors still look great, so I ended up putting them back in so that maybe I can sell the new sensors later. Those suckers are expensive!
I have a spares set of front sensors, both left and right that I will be swapping tomorrow, but I highly doubt that will do anything. My only other thought was that the steering angle sensor was off. I know, at this point you're probably wondering how the steering angle sensor could randomly go out of sync… Well I forgot to mention a key piece of information… The day before this issue first popped up, I installed a new head unit! I figured it would be insane that a new radio could cause such an electrical issue, but I had the battery unhooked during the install so I thought it was perfectly logical that the steering angle sensor may have done something wonky.
I parked the truck with the wheels slightly turned, and disconnected the battery for a few minutes. This would make sure that the steering angle sensor would go through its auto calibration process when next I drove the truck. I started the truck, VDC light was on steady so I knew the sensor was ready to self-calibrate. I drove in a nice straight line down the street until the light went away. I go on the freeway and it still happens! So I figure I’m running out of options at this point… I removed the new head unit and reinstalled the old one. It was a long shot but you never know with modern electronics and interference. Didn’t help one bit lol!
I did the steering angle sensor thing once more after I swapped the old head unit in and still nothing. I’ve checked all of the grounds that I can see and they’re all tight and no corrosion. I am 100% convinced its an electrical problem, and I know it will still show its ugly head after I replace all of the flex lines and bleed the system, I just know it.
My last thought worth noting was maybe all of the sudden I'm just some sort of crazy driver... I disconnected an ABS sensor so that the ABS and traction control system would deactivate and drove the same roads in the same driving style. I didn’t notice any out of the ordinary handling characteristics and no wheel spin or lock at all. Then I decided I didn’t have anything to lose at this point and drove like a daemon, it pushed hard in the corners as you would expect, and had a ton of body roll, but handled very predictable through the turns. Sure I could kick the rear end out if I really tried, but that was only under the most extreme conditions.
At this point I’m mostly out of ideas, since I’m sure it has to be electrical, but I have no steady warning lights. It's not so severe that I feel unsafe, but it sure is annoying, and should not be happening. I’ll replace the front wheel speed sensors tomorrow but I don’t expect much. You never know though, so keep your fingers crossed…
If anyone out there can think of something I missed, it’s a 2010 V6 with 42k miles on the odometer. I’ve been at this for just shy of a month now, if you can figure it out I will be eternally grateful! :bow:
To start, I have no warning lights on the dash whatsoever. I have no performance issues to suggest an obvious problem that needs fixing. My problem is with the traction control system (via the ABS) activating in all sorts of situations where it shouldn’t, and hasn’t before.
If you can imagine, your going down the highway and take an exit ramp, left or right, your choice. You coast from 60ish down to 40ish and take your sweeping exit without touching the brakes or gas and all is good. Now if you were to take the exact same exit, at the exact same speed, but you touch the brakes or gas after you have started turning the steering wheel, that is when I am getting an intermittent SLIP light and I can feel the brake pedal pulsing and hear the ABS actuator under the hood. I’m not talking about a hard press on the brake pedal, or mashing the gas, I’m talking about a normal stead pressure situation. And what’s even stranger is the SLIP light won’t go away until the vehicle is moving in a nice straight line again, regardless of pedal input.
Now for what I have done to attempt to remedy the situation, and thus far failed: First I inspected all of the friction parts. I removed all of the pads and rotors, no problems. Rotors don’t have much runout at all, and pads are about 20% worn so they still have plenty of meat. The parking brake shoes had some caked on mud so I disassembled and cleaned everything. Fresh grease on the contact surfaces and a nice adjustment on the star adjusters and the parking brake is like new.
I checked all of the brake lines, and everything looks good. I did a two person bleed and the fluid wasn’t too dark, but I did get a few very tiny air bubbles from the rear drivers side. I’m suspicious that those bubbles may have been introduced at the bleeder, but either way once they came out no more air followed. In any case, I have new rear stainless lines waiting to go in since my old stainless lines are 5 years old now. I’m just waiting on the front lines to come in. And I went ahead and bought a Motive Products power bleeder and a half gallon of brake fluid so I can flush the whole system. I also ordered new hardlines for the front since they got a little rusty from grinding dust when I did the hydro bumps. All of the lines and bleeding should be done in a week, but I really doubt that will solve my problems.
I also checked all of the calipers to make sure the pistons weren’t frozen, everything moved in and out as it should. I then removed the slide pins and found that the lower slide pin on each corner had a lot of resistance to moving due to swollen rubber. The pads aren’t showing any unusual wear so I don’t think the slide pin problem is doing much right now, but in any case I ordered new lower slide pins for each caliper, those are coming in with the new hardlines next week. I also got the fancy clear 3M silicone based brake paste that Nissan uses from the factory to lube the new slide pins with. I even took the mechanical side one step further and checked the brake pedal free height, and stroke. Both measurements were spot on with factory spec, as they should be since the brake master and pedal assembly have never been touched.
So by now you are probably thinking its an electrical issue, as I was too! I had figured it was electrical anyway since it also happens when you press the accelerator, not just the brake pedal. So here’s the whopper; I replaced both rear wheel speed sensors and the problem is still there! The old sensors still look great, so I ended up putting them back in so that maybe I can sell the new sensors later. Those suckers are expensive!
I have a spares set of front sensors, both left and right that I will be swapping tomorrow, but I highly doubt that will do anything. My only other thought was that the steering angle sensor was off. I know, at this point you're probably wondering how the steering angle sensor could randomly go out of sync… Well I forgot to mention a key piece of information… The day before this issue first popped up, I installed a new head unit! I figured it would be insane that a new radio could cause such an electrical issue, but I had the battery unhooked during the install so I thought it was perfectly logical that the steering angle sensor may have done something wonky.
I parked the truck with the wheels slightly turned, and disconnected the battery for a few minutes. This would make sure that the steering angle sensor would go through its auto calibration process when next I drove the truck. I started the truck, VDC light was on steady so I knew the sensor was ready to self-calibrate. I drove in a nice straight line down the street until the light went away. I go on the freeway and it still happens! So I figure I’m running out of options at this point… I removed the new head unit and reinstalled the old one. It was a long shot but you never know with modern electronics and interference. Didn’t help one bit lol!
I did the steering angle sensor thing once more after I swapped the old head unit in and still nothing. I’ve checked all of the grounds that I can see and they’re all tight and no corrosion. I am 100% convinced its an electrical problem, and I know it will still show its ugly head after I replace all of the flex lines and bleed the system, I just know it.
My last thought worth noting was maybe all of the sudden I'm just some sort of crazy driver... I disconnected an ABS sensor so that the ABS and traction control system would deactivate and drove the same roads in the same driving style. I didn’t notice any out of the ordinary handling characteristics and no wheel spin or lock at all. Then I decided I didn’t have anything to lose at this point and drove like a daemon, it pushed hard in the corners as you would expect, and had a ton of body roll, but handled very predictable through the turns. Sure I could kick the rear end out if I really tried, but that was only under the most extreme conditions.
At this point I’m mostly out of ideas, since I’m sure it has to be electrical, but I have no steady warning lights. It's not so severe that I feel unsafe, but it sure is annoying, and should not be happening. I’ll replace the front wheel speed sensors tomorrow but I don’t expect much. You never know though, so keep your fingers crossed…
If anyone out there can think of something I missed, it’s a 2010 V6 with 42k miles on the odometer. I’ve been at this for just shy of a month now, if you can figure it out I will be eternally grateful! :bow: