ABS and Brake light on. What does it mean?

Asked by slick75 Feb 08, 2010 at 02:26 PM about the 2001 GMC Sierra 1500 SL Standard Cab LB

Question type: Maintenance & Repair

My abs light and my brake light is on, I heard this is a pretty common issue with these trucks. What
are some recommendations on a starting point for troubleshooting.

58 Answers


I have the same thing on my truck. what year is yours? i got it checked out at the shop and they said that i would have to replace the abs computor which is about $2500 CDN

153 people found this helpful.

i had that same problem and all my car need was break fluid .. i guess thats the cars way of telling u you need break fluid !! hope it helps

74 people found this helpful.

In many cars and trucks, the abs sensor is built into the wheel bearings of each wheel. These thin wires can become corroded and break, especially if you live in the Northern states where road salt is a plenty in the winter. As the previous reply stated- check the fluid first. If all is good, you could contact a GM dealership and have them scan your system with a Tech2 scanner. That would be able to tell you exactly what wheel is causing the trouble and DTC. ( diagnostic trouble code). Or you could pull each wheel, disconnect the bearing harness, hook up a continuity tester to the two leads and spin the bearing. If the meter changes its reading, then that bearing is good. If it stays at 0, then the wire internally is broken, causing an open circuit, therefore causiung the ABS/brake light to illuminate. Good Luck

181 people found this helpful.

Mine sometimes comes on when I start the truck, and sometimes when I am moving at constant speeds. Sometimes, it can be a month or more, before seeing the light come on. I have read the wheel sensors may be dirty. How does one clean them? Does the wheel hub, or wheel sensor need to be diassembled, in order to clean it?

509 people found this helpful.

what happen to mine was it came on and off and i hooked up the scanner and it said the speed sensor so i changed the wheel bearing and it fixed the problem

71 people found this helpful.

Im having a problem on my 2004 sierra where my abs light comes on when i hit bumps in the road. but then it will go away either on its own or when i turn the truck off and back on. this all started happening after i got my tires aligned. ive already replaced the front two wheel bearings this year as well

278 people found this helpful.

KevDizz, that's the same thing that's happening to me except I never had the tires aligned. I replaced the sensor that the code came up for and still comes on and goes off when it wants to.

77 people found this helpful.

Or could mean u need to change your brakes

44 people found this helpful.

I have a question abs because it pop up my dashboard and I am driving a GMC ENVOY THE ON MY TRUCK IS A 2000 WHAT SHOULD I DO

222 people found this helpful.

I have a 2004 GMC Sierra Truck. The transfer case will not engage into four wheel drive. I took it to a GMC dealer and they are saying that is internal, but can not diagnois it until it is taken apart. Anyone have any suggestions?

83 people found this helpful.

I have a 98 Blazer. My husband just had the clock spring, both airbag sensors front driver and passenger replaced, vacuum hose, front sway bar, all front brakes - rotors, hub assemblies, calipers and that was just to get it inspected! Since I got it back however the abs light was coming on and off and the left front brakes would bddddtttt grab and make an awful ffflllllpppp sound and scare me to death. Took it to Auto Zone and the girl put the code diagnostic on it and showed me it was the left front brake with a code of 225 and 227, the speed sensor. Took it and got that fixed this morning and that fixed the braking problem but now the ABS light is on and won't go off at all. They told me that I needed to have the complete system diagnosed for all codes and wires, etc. could be bad or something wrong. HELP! Does anybody have any other cheaper ideas! I'm on full disability, my husband just laid out $1,500 to get all I talked about above fixed, I laid out $184.00 for the speed sensor. I'm being drained fast! WHAT could it be?! Thanks!

125 people found this helpful.

I replaced the speed sensor and it still came on so then I ordered a new hub assembly which came with a speed sensor(didn't know that) so I put that on and haven't had a problem since, been about ten months now. Now I have an extra sensor. Wish I could help more, was yours a repairable or in a flood or something.

37 people found this helpful.

Loztcauze: My husband as I said in my post had all rotors, hub assys, calipers, ALL of it replaced brand new. No it was garage kept for the entire life of the vehicle prior to my purchase. It's in basically mint condition. Thanks anyway!

19 people found this helpful.

the cause for the abs light and brake light to come on is because of your master cylinder is on its way out i had it happen on my truck replaced the master cylinder and the lights have not come back on it common for this to happen if had to replace it in a couple of vehicles of mine the are gm modeled vehicles

57 people found this helpful.

@ jessegm1991 - Actually, my husband who used to build cars and was 1 year away from rookie NASCAR status when we married checked all around my Blazer and the MC was and is fine! What it turns out to be is simply an open circuit when I had the codes checked. So thanks for your expertise.

24 people found this helpful.

ok that something i looked into before i replaced it there wasnt open circuit it was bad but i also found out that my hub is bad everything in it it hasnt been replaced im doing that today

14 people found this helpful.

Are you talking about the ABS computer unit, those run about $300.00 where I live. Everything works fine but just the abs light on. It passed inspection and they told me not to worry about it. The ABS brake sys works fine, stops on a dime.

17 people found this helpful.

could a wheel speed sensor being disconnected during an alignment cause it to pull to one side? 97 GMC Yukon

35 people found this helpful.

I have a 2000 GMC Sierra 1500 with the ABS lights on also. Truck runs like a dream. I was told it was the E break line. IDK if that's true or not at this point but it has been to 6 states repeatedly in the last 3 years & ZERO issues. On a side note my friend just bought a 2001 GMC (same truck & same lights) still runs like a dream also... IDK if the lights are more than just annoying inconvenience that GM triggers to get more $$$... Neither of the trucks seem to have any REAL issues.

53 people found this helpful.

My abs lite came on turns out I needed new brakes which I got abs lite still on does it have to be reset .

144 people found this helpful.

I'm having some trouble on my 04 saturn vue ... The ABS light the emergency brakes light my traction control light and the service car light comes on and all my gags stop working , at some point my gags will work but most of the time it won't .. Anyone know what can be the main issue

23 people found this helpful.

Ecm modul ground wire,, clean it and put it back ,, when ligth turn on and off , it make no good ground, and sometimes it does

31 people found this helpful.

Lol i removed the bulbs. Ahh thats better and i didnt even spend a penny

51 people found this helpful.

Ok, so after reading all posts, I'm similar with abs and emergency light coming on every few starts after having front end aligned. It causes the cruise control to be inop. Had brake pads changed all the way around and mc had plenty of fluid. My question is how can you tell if mc is good, and if car needs reset? Reason I ask is when sensor said I needed an oil change, after having the service done, it still displays the need oil change message. Been a chevy driver a long time but first time dealing with all the bells and whistles of my recently purchased 2004 z71 tahoe

31 people found this helpful.

Reset the system. Cured my messages

37 people found this helpful.

@ Maris: Exactly how do you "reset the system"? Do I have to be a mechanic to do that? Which I am not, btw

96 people found this helpful.

Go to a shop with a diagnostic reader and ask them to. Best 40-60 bucks you'll spend. But ask them to read it first. :) case there's something going on you should be aware of

14 people found this helpful.

Right after I had the speed sensor replaced last year when the ABS light came on when I start it up and it won't go off, I took it to Advance Auto and the code came up that it was an open circuit. Should I still take it for what you suggest when I already had that read? The brake light goes off as it's supposed to. Just the ABS light remains on. I was told that it being on would not affect my getting it inspected as long as the brakes work fine. I'm not thinking it's anything but just the circuit broken somewhere because when I slam on the brakes, it stops straight on a dime. Our family Master Mechanic told me not to worry about it because as long as the brakes are functioning properly, it means the ABS is functioning properly. He checked everything. He couldn't figure out what the code indicated as well.

11 people found this helpful.

There is nothing mechanically wrong with your GMC truck. This is a GM engineered ploy to get you to take your vehicle to the dealer for a remedy. I did and it cost $45 and a tolerance of morons at the dealer telling me there was "water" in the fuse box? I paid the bill, started the truck and the ABS light and ding dong came on as it had before. 2 years later it is still coming on about every other time I start the truck! With 33,000 city miles on it, the ABS has never been used since I do not drive on the interstate for longer than 10 miles. Gotta love GM, they'll try anything to scare the customer into giving them more business!

19 people found this helpful.

Same here. My ABS ligjt comes on. I have a 99 chevy silverado 2500 4x4 6.0. What could i do to take that off?

51 people found this helpful.

To all with this problem NHTSA issued a recall on most of these vehicles. Recall #05V379000 contact GMC @ 866-996-9463 or GM @ 800-630-2438

36 people found this helpful.

Unfortunately for those of us with pickups earlier than year model 1999, the NHTSA recall doesn't include. To be more specific, the recall is for years 1999-2002.

20 people found this helpful.

I own a 03 Yukon XL and this light keeps coming on ...check ABS stystem....but i have had my brake system checked and all was fine, light keeps popping on and then we unplugged batter thinking that it needed a reset and it stopped for like 3-4 days then here is comes again.....I want to take to the dealer usually i trust them but after reading these responses above not sure what to do?

9 people found this helpful.

Guy on youtube showed a ground wire screws that bolts in to near the radiator firewall on the driver side. That might be a ground for the abs module that gets corroded and causes the intermitant problem just like a loose battery cable would.

15 people found this helpful.

The ABS and brake light came on in my 2005 vue. I pulled all the wheels, brakes looked fine and topped off mc. There was a lot of rust on the front rotors - that may be flaking off onto the sensor pickup. About a week later the brakes started grabbing. I pulled the small abs fuse, no change. Pulled the big 40 abs fuse, brakes no longer grab/drag. AZ couldn't find a brake code. I'll try AA today. May just replace rotors just to be sure.

4 people found this helpful.

ABS light will come on if brake fluid is low, sensor is on the fender side of the master cylinder but otherwise 20% broken wheel speed sensor wire or just corroded and making a bad ground where the bolt holds it to the hub. 80% of the time it's a bad speed sensor , either way you have to remove the brake caliper and rotor to get to the sensor. Remove the sensor, clean the area around the hole it goes into and blow it out with air then replace the sensor. If you have a good diagnostic tester it will tell you which side is bad Left or right. Replace, then reset the dtc code and your good to go. Once in a great while it will be one of the expensive ABS electronic components but if you aren't sure get a second opinion unless you just like throwing your money away. The free test they do at most auto parts stores they do with a $30 code reader which won't properly identify the problem. Also you need to clear the trouble codes and retest, sometimes they old codes stored in the ECM that were never cleared after repairs were done.

9 people found this helpful.

Heres a good one i jave a 2011 chevy silverado 1500 my stability/traction control lights have been going nutts lately comeing on and off but when the (service stability track light) comes on so does the (ABS) light....well it did that for a week or so, and got worse! now its on 90% of the time and when i start it up it wont be on i put my foot on the break to shift and they both pop on and my truck will not shift out of park!! I literally have to keep my foot in the break reach down under the dash finth the wiring harness that goes to the break unplug it, WITH FOOTBON BREAK STILL shift the truck out of park to drive then plug it back in, But my break lights DONT WORK they are on but when i step on the break the flash brighter then go back to running lights.......the abs light goes out untill i plug it back in!!! I think the NOT SHIFTING part has to do with the neutral safety switch or the truck not recognizing that the break is applied...i had someone tell me that its the modual, and i had someone tell me its a selanoid sorry for the terrible spelling but can anyone help me and give me some ideas and were to look for this problem pos chevy that i paid way to much for! Or a beer can basicly!! Thanks justin

12 people found this helpful.

I have a 04 mercury grand marquis my abs and brake lights are on they did all testing but could not come up with anything but one test came up with code 1445 some thinks my be master cylinder could that be master cylinder for both lights to be on same time

2 people found this helpful.

Someone Just Said That There Is A Recall 99' & Up On The Abs Lights Coming On, Mine Is A 99' Late 99' Chevy Silverado LS 2500 6.0 V8 Crew Cab Long Bed, & The Abs & Brake Light Is On, & I'm Being Told Its The Abs Module Underneath The Drivers Side Frame Rail, Is This Recall True & Are They Gone To Fix It & Who Do I Call? Donnie South New Jersey

29 people found this helpful.

The master cylinder has two separate circuits front to rear. When one circuit has a fault the other circuit remains working. If a circuit faults it is usually due to a sustantial loss of brake fluid or a leak. This signals the abs and brake lights on vontrol panel to illuminate bright.

3 people found this helpful.

I have a Toyota Camry 2007 LE and have same problems of ABS, BREAK light ON/OFF and RPM, Speedometer and Temperature meter UP/DOWN. I cleaned speed sensor and also cleaned the wire attached to ABS system. This helped me a lot and frequency of malfunction has decreased a lot but not completely stopped. I am going to check/replace the wire connectors for speed sensor.

1 people found this helpful.

I had a 2003 Silverado and the ABS light came on then brakes started slipping & grabbing at reduced speed. My mechanic saved me a lot of money finding out that theres a range of years that GM has a recall on vehicles due the ABS sensors ability to get corrosion and dirt on them causing issues. All he did was clean the sensors and it was fine since. temple62 what the hell difference do you think city and highway driving has to do with ABS. Do you go over 12mph? Do you use your brakes? If yes you are using your ABS.

4 people found this helpful.

Just fixed my truck and it was the ignition switch. Not the key lock but the plugged it switch behind the key switch. See u-tube for how to. Abs light and emergency brake light came on. Then in the morning when I went to use my heater it did not work either = ignition switch orange wire is dead.

3 people found this helpful.

just because your brakes are working(as in your car slows down) does not mean your ABS is working. The test would be to lock up the brakes. Does it lock the wheels up and skid or does it lock/spin/lock/spin very quickly and you feel the abs actually kick in?

6 people found this helpful.

the abs light on indicates that the abs system has been disabled ! no you will not be able to tell unless you panic stop are otherwise slam on brakes. abs are antilock brake system is designed to control panic stops ,the system contains several sensors that feed the module wheel speed ,by this information the computer can correctly see how fast each wheel is rotating therefore if one wheel begins to rotate at a different speed the brake system is taken control off by the abs system which then pulsates the brake system to control wheels to prevent one are more wheels from skidding .if a abs light is on then the code needs to be pulled ,with code it is possible to pinpoint which wheel are part of system is affected . to diagnois an abs problem you need to understand all the pieces in your system because they do differ in different makes and models. to start at the wheel most have either a ring of teeth on the axle of most front wheel drives are a plate inside the wheel bearing . as wheel rotates the sensor sends signal to computer . hope this helps .remember not all mechanics are out to steal your money and cars are more complex than a lot of people even begin to understand . but with some real information these problems when diag by a pro can be resolved easly. REMEMBER codes do not point to the bad part please don't change parts just because code . a front speed sensor code could be a bad wheelbearing more often than the sensor because the sensor reads the bearing yet the code dosent read bearing it reads bad signal are some term there in .

8 people found this helpful.

it could be your front CV joint if it's 4x4 or front wheel drive, bad joint could cause excesive heat to the sensore

2 people found this helpful.

It's been fixed. My family Master Mech. said when he went to pull it out, it crumbled in his hands. Close call! Car all fixed now. New water pump, clock spring, brakes, cv joint, tune-up, oil changed, tires rotated, a/c heater problem fixed, she's doing great! Thanks for all the answers!

3 people found this helpful.

My 1998 gmc truck 1500 brakes not releasing abs

5 people found this helpful.

My 2008 Saturn Vue had the ABS light the brake light and the traction control light on. I took in to get the oil changed looked at the invoice and brake fluid was checked off and marked as good. I researched everything to come to a conclusion that it was probably just a sensor and the car would drive fine mechanically. I took it to a tire shop and they confirmed it was a sensor. I drove the car for another 4K miles and brought it back to the same location and had my oil changed. Once again brake fluid marked as checked and good. Tonight after about a year of this car riding around with all of these lights on I decided to check the brake fluid for myself... It was bone dry. I drove to the gas station and but fluid in the tank and turned my car on. All of the lights were off.

1 people found this helpful.

2003 GMC SIERRA TRUCK. checked all over found float is bad in master cylinder

4 people found this helpful.

I dnt know but when my abs light flickers off and on my 94 suburban starts puttering wanting to stop does anyone know why this is

2 people found this helpful.

It could mean u have air in the system, brakes need change, bad reservoir cap, a leak in ur lines, bad speed sensor or bad abs sensor. Sometimes it could be the reservoir seals. Very rare for the computer to have to be replaced. However the cheap way to test the brake computer is to get one from the junkyard n swap it out. Bleeding the braked in the wrong order can cause the issue as well, but for those that don't know the order in which to do this it is......1st rear passenger, 2nd rear driver, 3rd passenger front, n then driver front, add fluid as needed after each step and car has to be on while bleeding for the the proper pressure.

2 people found this helpful.

I have a 2005 GMC Sierra 1500 ABS light recently came on need to know how to turn it off need to smog the truck

6 people found this helpful.

I have a Ford with this same issue. I had to pull the exhaust, fuel tank, two motor mounts and remove the transmission and take the passenger side door and seat out. There was a wire that became loose. It was about $4600 at the dealership. Still does it.

1 people found this helpful.

I had a cracked tone ring inside the drivers side hub it was tearing the abs sensor up! Had to reply the hub it was a 4x4 Yukon

1 people found this helpful.

I have an '03 chevy Silverado single cab. My abs came on when. I came into work tonight, and I know I need a new wheel bearing on the front passenger side,. It does make a small clunking sound when I turn...any ideas if it's just the wheel bearing or if it may be something else behind all that?

1 people found this helpful.

I have a 2003 Chevrolet Silverado 2wd ext cab LT. Everything was working great i have owned the truck for 12 years since the truck had 60,000 miles. Drove it to work parked it inside went to leave, started normal went to roll down the window and seems to lose all power my auto climate control reset to i think 74 degrees and the message display disappeared and the abs light and brake light came on. After i shut the truck off and back on multiple times was fine(message display came back) went to roll up the window happened again. The entire way home everytime i used the turn signal or windows issue came back. I parked the truck for 2 days starts just fine concern still present. Tested alternator alternator passed test. Selling truck need to fix fast.


I have a 2003 z71 5.3 4x4 single cab. After i had the rear drivers side brake line blow I had a parking brake light and service brake system come across my display. So i took truck to shop they replaced line, when i went to pick it up they said it was all good paid 235$. Brakes work fine now but I still have both lights on. Heres how I fixed it.. Under the hood next to the brake reservoir there should be an aluminum 4 way splitter with a 2 pronged plug (atleast on mine) this is a fluid differential sensor plug. Unplug it, did your light go off? If not you probably have a bad sensor. If it did try the following Disconnect said plug an unscrew from splitter. Now look down inside do you see something covering the bottom like its closed or is it open? If it looks closed try spraying some 3M brake cleaner down in there an tap with a hammer, then start truck an apply brakes a few times an tap some more. I also pulled both end plugs an cleaned with brake cleaner and put the plugs back in. (Careful as the front plug with nipple has a high pressure spring behind it, dont lose these and be sure everything is cleaned before putting back together.)

1 people found this helpful.

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