Chevy and GMC Duramax Diesel Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
I have a 2007 Silverado HD2500 duramax that I have been having brake issues with. When I am coming to a stop and am almost at a complete stop (5MPH) my brake pedal feels like it releases, drops about an inch and almost feels like the ABS kicks in. It is a very unsettling feeling when I am pulling a piece of equipment. Has anyone else had this issue?

2007 Silverado HD2500 Duramax
less than 36,000 miles but more than 3 years old
4 inch exhaust front to back

Thank you in advance for any ideas
 

·
Registered
Joined
·
287 Posts
Does it feel squishy? If so could be master cylinder. I had a similar issue with a civic a few yrs back. I know completely different, but a start if u haven't checked that yet. Also could be air in the lines.
 

·
Premium Member
Joined
·
26,485 Posts
That can be indicative of a front hub/bearing failing...usually has the ABS light come eventually. Check for play.
Edit...if no play, could be the fluid. When was it flushed last?
 

·
Registered
Joined
·
510 Posts
I also believe its an issue with abs sensor. Probably be replacing bearings soon.

I had this same problem when I put a hub assembly on an 08 that was for an 06
evidently the tone wheel in the hub has a different tooth count on the newer trucks.

It was scary and only did it right before it came to a stop!!! No codes either
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
Thanks for the replies. I would have never thought that a hub bearing would be the issue. It does not make any noise, no vibration or anything. The brakes are a little squishy but even my 95 and 00 Chevrolet trucks were, so I thought that was pretty normal. I have not flushed the brake fluid, it this a known problem also?
 

·
Registered
Joined
·
55 Posts
I had the exact same problem. B4 buying brg cartridges, if you jack it up, shake the tire and really dont feel movement in brg, remove the one allen bolt from the abs sensor that goes into the top of the brg. Very carefully wiggle it out, use a shop vac while doing it so you don't drop rust in the brg/abs hole . while using the vac, or plug the hole if you dont have a vac, scrape and emery the rust that is on the abs mounting mating surface on the brg hsg. clean , apply a little grease for rust prevention and install sensor. it only takes .010 rust under the sensor to trigger the abs system. do it to both front wheels and you should be ok.
 

·
Registered
Joined
·
510 Posts
I am almost cretain its an ABS sensor problem.. Does it feel like the pedal pushes back at you somewhat?

It necessarily doesnt have to be a bad hub bearing, could be just junk in the notches in the tone ring that the sensor reads causing a bad signal.

You can pull the wheel and the rotor and sensor and see the tone ring and make sure nothing is on the end of the sensor.
 

·
Registered
Joined
·
784 Posts
My truck is doing the same exact thing- subscribed


Sent from my Autoguide iPhone app
 

·
Registered
Joined
·
510 Posts
I had the exact same problem. B4 buying brg cartridges, if you jack it up, shake the tire and really dont feel movement in brg, remove the one allen bolt from the abs sensor that goes into the top of the brg. Very carefully wiggle it out, use a shop vac while doing it so you don't drop rust in the brg/abs hole . while using the vac, or plug the hole if you dont have a vac, scrape and emery the rust that is on the abs mounting mating surface on the brg hsg. clean , apply a little grease for rust prevention and install sensor. it only takes .010 rust under the sensor to trigger the abs system. do it to both front wheels and you should be ok.
You beat me to it, but yes, I believe this is exactly the problem ^^^
 

·
Registered
Joined
·
118 Posts
You have a weak ABS sensor or bad wheel bearing. A friends wifes Jeep did the same thing and ended up being the ABS sensor on the rear wheel. I have also seen it happen when the gap on a sensor is too much. Pull the front sensors and if they have shims on them pull one off and test drive. If that fixes it replace that wheel bearing. Reason being, your bearing is going bad and the sensor ring is shifting with the hub and causing it.

Re'
 

·
Registered
Joined
·
117 Posts
Wheel bearing or sensor as the others are saying. If they are tight try cleaning the sensor. If this still does it have it checked with a scan tool. I have seen some of these have good bearings and a good sensor but still have an intermitten issue and only a scan tool could pick up on which bearing was the problem. There would be no codes and the Tech-2 would only pick up on the bad bearing with the oscilloscope feature.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #12
THAT DID IT.. I pulled the ABS sensors out and they both had thick rust underneath. I stuffed a ball of fabric into the hole and hit it with an air gasket remover to clean it up. Put the sensors back in and then painted them to reseal. Test drove it and the issue is resolved. THANK YOU to all that replied.
 

·
Registered
Joined
·
118 Posts
Awsome...Probably will be a temporary fix as it sounds like the bearings are going bad.

Re'
 

·
Premium Member
Joined
·
1,374 Posts
Easiest way to tell which bearing/ sensor is bad without a scan tool is to drive 15-20 mph on a flat straight road. Hit the brakes as you normally would and see which side your steering wheel jumps to. If it steers to the right, the left hub assembly is bad, and vice- versa. This happens because the bad assembly drops to 3 mph while the other side stays at 5 mph. The 2 mph difference is enough for the abs module to think that the slower wheel is locking up, so therefore it actually engaged the abs pump motor to release the braking pressure to the slower wheel and allow it to catch back up to the faster wheel. Many times it will not put an abs light on or set a code because it happens so fast and the computer is just doing what it is supposed to.( release the brake to the slower wheel)
 

·
Registered
Joined
·
31 Posts
i have seen this problem alot on the gm trucks, gm has released a service bulletin on it.
the problem is extra air gap in the front abs sensors caused by rust and corrosion.the bulletin is long winded but here's the how to.

the only special tool needed is a digital volt meter

remove caliper,brake pads, and brake rotor from front axle.unplug abs sensor and attach the meter to the sensor side.set meter to measure AC voltage, spin hub assembly, reading should be over 350mv, if its lower than that it needs cleaned.
to clean...
remove the allen head bolt that holds the sensor in the hub.using a pair of pliers and a flat head screw driver twist and wiggle the sensor to gain room under it to insert the screw driver and gently priy,twist and wiggle til it comes out.now at this point it may or may not break the outer covering off the sensor exposing the wire.if the outer covering breaks off and stays in the hub, dont freak out yet as long as the copper wire is not hanging from the sensor it will still work, if the wire is hanging out then you need a new sensor, you can replace just the sensor but it cost as much as a new bearing most times.
once removed lean the area under the sensor, at the shop we use sand paper and files to remove all rust from the area, you may wish to plug the hole going to the bearing to keep debris out of there.also clean the base of the sensor, make sure there is not rust built up on it.NOW gm reccomends using the zinc paint the have to paint the area under the sensor before reinstalling, we do this and it helps make the repair last longer.after cleaning and reinstalling the sensor, check your reading again with the meter, you should see a noticable difference from before.put the brake back together and do the other side the same way.

this is the way we do them at the shop, the first one we done was over 5 years ago and it never came back with the same complaint.this applies to any gm truck suv even the vans that have the same hub bearing/sensor, it works for them all.
 

·
Premium Member
Joined
·
1,374 Posts
Good info!
 

·
Registered
Joined
·
31 Posts
ive never seen any shims under the sensor.that would be a new one for me.if there is something there i would would say clean everything and reassemble as it was, then take a reading with multimeter and see what your ac voltage is, if its still low remove the shim and try again.
 

·
Registered
Joined
·
13 Posts
I'm glad I found this thread. I just acquired a 2007 2500HD Sierra Classic and its doing the exact same thing, releasing brake pressure almost as the truck stops. I'm going to check my ABS sensors for rust underneath the mounting point.

Thanks for the advice.
 
1 - 19 of 19 Posts
Top