Uranium238

I have a strange issue that I believe may be wheel speed sensor related. My 2011 GL450 shudders on acceleration and triggers the traction control warning light. The shudder is so hard that the ESP kills the power. It's almost as if I can't drive past 4000rpm.

However, when cruising on the freeway and going WOT, there is no issue. Seems to only occur in the first 3 gears.

Thoughts?

quron_southwest

Put the car in dyno mode with the secret menu in the instrument cluster. If the car shifts normally and everything it’s more than likely gonna be a wheel speed sensor. It almost got me killed in 80mph San Antonio traffic once...

Uranium238

Took the GL on an empty road last night and did a WOT run. Car doesn't want to accelerate normally. There is significant bucking or a surging in first and second gear with the ESP light flickering throughout entire rpm range. I did feel and HEAR the driver side wheel spin though too before the traction control kicked in. Didn't think spinning wheels on a 4 wheel drive suv was possible. Doesn't sound right...

​​​​​​Would a wheel speed sensor do that too?

quron_southwest

Uranium238

Yes will give it a shot first thing in the AM. I just need to read up on how to pull up the secret menu.

quron_southwest

DennisG01

What is shuddering... the engine? Or are the brakes activating, causing the shuddering? What codes are you getting?

Uranium238

Shuddering is the power cutting out because the brakes are triggering the ESP. it feels like you lost half the cylinders when accelerating.

Wasn't able to troubleshoot this morning. Will do it tonight. I already ordered the sensors for the front since there is no record of them ever being changed.

DennisG01

Could you be confusing the ABS kicking in (brake pedal pulsating... "shuddering") with the computer pulling power? Just pulling power doesn't cause shuddering - power can be pulled, but throttle response should still be smooth... just not as much power on demand. Which came first... the chicken or the egg?

So the CEL is on, but you just haven't had time to pull codes? Or is it not even lit up? Usually a WSS will trip that. However, there could be dirt on the sensor or the reluctor wheel (could be using the wrong term, there) tricking the computer into seeing a locked up wheel.

Uranium238

The CEL is not on. As I mentioned before, only the ESP is triggered (flashing exclamation light) upon acceleration.

We have had some heavy rain here and this problem emerged right in the middle of the heavy storms.

quron_southwest

Uranium238

Narrowed it down to the driver side front. You don't even need to hook it up to a DAS to isolate. Just turn the steering wheel right and apply gas. You instantly hear a grind and the ESP flashes. That would be the brakes locking down that wheel. Try making a left turn and it won't do it.

Going into Dyno mode until my sensors come in.

DennisG01

I'm surprised your not getting a CEL. It makes me wonder if something is actually "wrong" with the sensor, or if there is simply some type of dirt/grime caught in there causing it to "sense" incorrectly.

Driver's side... or... is it the passenger side since when you turn to the right, it unloads the weight on the starboard side of the vehicle allowing the wheel to spin easier? I dunno - just thinking outloud here. I'll be curious to see what happens once you're in Dyno mode - first time I heard of that, myself. Might have to try that just for the fun of it!

BlownV8

The ABS sensors on the passenger side lasted around 220k miles and the drivers side around 240k miles. You can purchase on Amazon for $35 and it includes all 4. Go ahead and change them all since they typically go out around the same time.

Uranium238

I went big and bought Genuine front sensors at 116 a pop. Heard a story from an old tech friend why one shouldn't go cheap on them as they may not last that long. Aftermarket ones these days are made in China

For those reading, part number is 1645400917. There is no specific front right or left.

EDIT - Part number superceded to 1649058200 and may be a better sensor that lasts longer!

Uranium238

DennisG01 you're right. It is the right front. The noise resonated toward the left side from the right. The fact the right front wheel is unloading during a turn and triggering a false traction light is very plausible.

I don't see any write ups on the replacement so I will do everyone a favor who has the same issue in the future.

Uranium238

Got my sensors today. Part number was superceded I see..

DennisG01

I recently went through issues with a failing WSS on my '97 BMW. It caused different issues than you, but I was able to find specs so I could test each WSS to defnitively see if it was bad, or not. Maybe with some googling you can find the specs? I learned enough that the specs for my WSS is/was not necessarily the same as other model years so I don't think I can pass along any data to you. BUT, don't forget to look through the hole where the WSS fits - spin the disc brake as you look - you should be able to see pretty quickly what the WSS is seeing and whether or not there is gunk in there causing/adding to the problem.

I'm still surprised at not seeing any codes.

WinterPark321

Wheel speed sensor is fairly easy to change. Just remove wheel, remove the fender liner, disconnect the plugs, and follow the line to where the speed sensor is located behind the rotor area. My symptoms for wheel speed sensor were a check engine light, along with traction control, ESP lights on, along with limp mode. Changed all 4 and went with genuine as aftermarket brand speed sensors were giving the same fault, even with brand name or FCPEuro aftermarket sensors.

However, after changing all 4 wheel speed sensors, car would randomly go into limp mode but without any lights. Searched it up and apparently there is another "Speed sensor" in the conductor plate which appears to be a common failure with these 722.9 transmissions. However, since there were no check engine lights, dealer refused to change conductor plate/valve body and Indys can't change them since its a security part. We ended up changing the transmission fluid at an Indy and seems to have fixed issue for now. Hope this helps.

Uranium238

Right front wheel spins in Dyno mode. Left does too slightly when applying more throttle then normal. Streets are wet

Assuming this is normal??? Sensors are off in Dyno mode and you can tell esp is not trying to stop it. The truck accelerates fine with no problems.

Uranium238

WTH?! Is the abs sensor also include brake pad??? This doesn't look like the part number I bought. Unless that big black piece is a cover for the brake pad and abs sensor. Thoughts???

quron_southwest

Uranium238

It is. Called it quits because it's pouring rain for now. Trying to figure out how to pop off that cover.

EDIT: it is not a cover but rather both the wheel speed sensor and brake pad wear sensor sitting flush side by side.

Uranium238

For those of you who don't know and will be doing this, there is a clip inside the harness holding both the WSS and brake pad sensor. It can be removed with a flat screwdriver pressing on the right side of the harness where there is a small opening to expose it.


YOU MUST REMOVE THE WHEEL LINER TO REPLACE. IT IS VERY EASY TO DO AND TO REINSTALL

Uranium238

Damnit! After replacing the fronts the ESP light is still triggered under WOT acceleration past 4000. Now what???

Is it the rears triggering it?