Question about 2002 GMC Safari

2 Answers

I have abs and brake light warning lights on, however, when checked by mechanic the abs brakes are working fine. whats causing light to come on?

Everything else is running fine at 154,000 miles.

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2 Answers

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  • Master
  • 283 Answers

Anti-Lock Braking System (ABS)
Purpose Anti-lock brake systems (ABS) - generally also referred to as anti-lock
systems (ALS) - are designed to prevent the vehicle wheels from locking
as a result of the service brake being applied with too much force, especially
on slippery road surfaces.
The idea is to maintain cornering forces on braked wheels to ensure that
the vehicle or vehicle combination retains its driving stability and manoeuvrability
as far as physically possible. The available power transmission
or grip between tyres and carriageway should also be utilised as
far as possible to minimise the braking distance and maximise vehicle
deceleration.
Why ABS? Although today commercial vehicle brakes are designed to a very high
technical standard, braking on slippery roads often results in potentially
dangerous situations. During full or even partial braking on a slippery
road it may no longer be possible to fully transfer the braking force onto
the road due to the low coefficient of friction (friction coefficient (k)) between
the tyres and the carriageway. The braking force is excessive and
the wheels lock up. Locked wheels no longer provide any grip on the
road and are almost incapable of transferring any cornering forces
(steering and tracking forces). This often has dangerous consequences:
- The vehicle becomes unsteerable
- The vehicle breaks away in spite of countersteering, and starts to
swerve.
- The braking distance is significantly increased
- Tractor-trailer combinations or semitrailer trains may break away or
jackknife.
Load sensing valve influence On dry roads today's load sensing valves (ALB) alone are often capable
of preventing the wheels from locking if the vehicle is unladen; they also
help the driver to effectively grade the braking process on wet road surfaces,
but they are unable to prevent locking as such (no slip monitoring).
In addition, they are unable to counteract any overreactions on the
part of the driver, or any variances in frictional or adhesion coefficients
which may apply to different sides of the vehicle, or indeed to its different
axles (?-split road surfaces).
Benefits of ABS: Only the Anti-Lock Brake System (ABS)
- guarantees stable braking characteristics on all road surfaces.
- maintains steerability and generally reduces the braking distance
- prevents vehicle combinations from jackknifing
- reduces tyre wear.
Limits of ABS Although ABS is an effective safety device, it can not suspend the limits
defined by driving physics. Even a vehicle fitted with ABS will become
uncontrollable if driven too fast around a corner.
So ABS is not a licence for a maladjusted style of driving or failure to observe
the correct safety distance.
4
ABS Training Anti-Slip Regulation (ASR)
Anti-Slip Regulation (ASR)
Why ASR? Increasing the engine output (accelerating) on a slippery road surface
can easily lead to the maximum adhesion on one or all powered wheels
being exceeded causing them to spin, especially if the vehicle is unladen
or partially laden.
Spinning wheels when driving off or accelerating represent a safety risk
just like locked wheel do when braking.
Reasons - Wheels that spin transfer just as little cornering force as locked
wheels.
- They also no longer transfer any tractive power onto the road.
Consequences - Vehicles that do not move or get stuck.
- Vehicles that can no longer be steered, jackknife on uphill uphill
gradients, or swerve in corners.
Benefits of ASR ASR prevents the powered wheel from spinning and provides the following
benefits:
- Tractive power and cornering forces are maintained.
- Stable driving behaviour is ensured when moving off, accelerating
and negotiating corners on slippery roads.
- The indicator lamp (if installed) is used to warn the driver of slippery
road conditions.
- Tyre wear is reduced to a minimum, and the motor vehicle's drive
train protected
- The risk of accidents is further reduced.
ASR and ABS: ASR represents a worthwhile addition to an ABS-controlled braking system.
All that is required to turn ABS control into full ABS/ASR control is
an ECU with the additional ASR function and a few additional components
for controlling the differential brake and the engine. This why ASR
is only available in combination with ABS.
Even a differential lock for off-road use and ASR do not exclude but complement
each other.
Limits of ASR The traction capacity of an all-wheel driven commercial vehicle can not
be achieved by a motor vehicle with only one driving axle - not even with
optimal ASR.

Posted on Jun 25, 2015

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  • GMC Master
  • 450 Answers

FOR ONE THING CHANGE MECHANICS ! HE SHOULD HAVE FIXED THE PROBLEM, YOU MAY HAVE A SERIOUS BRAKE ISSUE ! IF LIGHT IS ON IT WILL NOT PASS INSPECTION ! YOU MAY HAVE AIR IN SYSTEM, NEEDS BLEED ! FLUID COULD BE CONTAMINATED , NEEDS BLEED OUT, REPLACED W/ FRESH FLUID ! ABS REQUIRES THAT THE REAR BRAKE CIRCUIT OPERATES BEFORE THE FRONT BRAKES, THIS PREVENTS SKIDDING, THE PURPOSE OF ABS BRAKES, CORRECT ? MASTER CYLINDER HAS SEALS, CONTAMINATED FLUID AFFECTS SEALS, BRAKE LIGHT WILL STAY ON UNTIL PROBLEM IS RESOLVED !!! REAR BRAKES IF SHOES NEED ADJUSTED, CLOSER TO DRUM ! THIS WILL HELP, BUT BLEEDING OUT ALL BAD FLUID & AIR IN SYSTEM IS PARAMOUNT !!!!!! BRAKE LIGHT SWITCH MAY NEED REPLACED, PROPORTIONING VALVE WHICH SEPARATES FRONT FROM REAR BRAKES , IS OUT OF BALANCE, THE VALVE NEEDS TO BE @ A NEUTRAL OR CENTERED POSITION, COULD BE STUCK TOWARD EITHER BRAKE CIRCUIT, MORE FRONT THAN REAR, UNDERSTAND ? THINK I COVERED YOUR ISSUE, PLEASE RATE MAY ANSWER ! THANKYOU,

Posted on Apr 02, 2013

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6 Suggested Answers

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Posted on Jan 02, 2017

keemo68

Ronald Mueller

  • 1263 Answers

SOURCE: ABS and brake warning light is on

it could be that the wheel sensor is either defective or it is not close enough to the rotor to read. if your not having a issue with braking under driving conditions i would jack the vehicles wheels off the ground and remove them then take brake clean and spray the sensor pick ups to remove any dirt or brake dust. also make sure that the plugs and wires to the sending units are ok also they should be no more than .050 of an inch away from the rotor you can use a feeler gauge to check this. please rate this

Posted on Sep 02, 2008

shocktroop40

John DeCosta

  • 155 Answers

SOURCE: 2001 Jimmy ABS and brakes lights came on

I hate to say it, but the abs control module might have died on you. Thats the boxy looking thing under the hood that has a lot of brake lines and wire connectors going into it. I have seen this happen before and it ended up being one of the speed sensors on the wheels but usually its the module. Take the truck somewhere to get the light scanned, and that will give you a better idea of what it is.

Posted on May 24, 2009

Anonymous

  • 9 Answers

SOURCE: no brake lights or backup lights

Did you check the back-up switch on the tranny, or the grounds??

Posted on May 27, 2009

bluetegjoe

  • 86 Answers

SOURCE: What are probable causes for an ABS warning light

The ABS system has no effect at all on normal driving or braking. There are many problems that will cause a warning. You could have a bad sensor at the rotors or low pressure at the accumulator. You should have the car checked by a mechanic since it is likely that the ABS will not work in a panic stop or in a slippery road condition though you will still have regular braking.

Posted on Jan 19, 2010

ZJLimited

ZJ Limited

  • 17970 Answers

SOURCE: several warning lights come on

You could check if you have front wheel speed sensors. they should be located in the front hub assembley, check for wires running along control arm. Additionally, the two first warning are refer at ABS Module, so, I suggest scanned to know exaclty which fault code is stored there. Some Autozone or AutoShop with reader codes scanner could make it.

How old is your battery? Some vehicles turn on this dash lights when this occurs and its time to new battery; if this its thru... don't forget that our vehicles disable the charging system for a few seconds until the idle stabilizes in cold weather. What this means is that a marginal battery may provide JUST enough juice to start the vehicle but not enough to keep it reading all the inputs and outputs from the PCM, TCCM and EBCM. It then throws multiple trouble codes.

It's simple to have a battery load-tested. (Usually free at any battery dealer.) You cannot tell the state of a battery by a simple voltage test; it must be load-tested.

Now, about heater/defrost, I suggest check the blower fuse, then the blower resistor pack if you've got the manual controls, then the blower motor itself. If you've got the digital controls, check the fuse and the blower first. If those are good, it's probably time to replace the control module.

If your blower only failed to work at the time of the indicator light flakeout, it's most likely the effect of the power being held back from other systems in order to allow for starting. If that's the case, it doesn't come back immediately after the truck starts. There's a lag while the charging system takes over and the PCM can allocate power to those additional sytems.

Additionally, I found this article and you could visit your dealer and ask about this TSB... I don't understand it all, but it does point to the problem: bad ignition switch.

------------------------------------------------------------------------------------------------------------------------------------------------
Subject: ABS Red Brake SVC And 4WD Light On HVAC Blower Inoperative - keywords B1375 C0379 DTC HI4 ignition IPC L04 MIL on U1000 U1041 PIT3832C (12/04/2007)

Models:
2004-2007 Buick Rainier,
2002-2008 Chevrolet Trailblazer models,
2002-2008 GMC Envoy models,
2002-2004 Oldsmobile Bravada

This PI was superseded to update Recommendation/Instructions and model years. Please discard PIT3832B.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s).

Condition/Concern:
Vehicle may exhibit a combination or all of the following symptoms: ABS light on, Red BRAKE light on, Service 4WD light on, HVAC blower motor inoperative. Various DTCs may also be present.

Recommendation/Instructions:
Diagnose for loss of battery voltage to the rear fuse block on circuit 300 ORN for the following fuses:

Note: Prior to proceeding forward with the information below, it is important to verify the voltage as indicated however it is equally important to verify the integrity of each circuit. This can be achieved by performing a voltage drop test or by adding a device to each circuit that will supply sufficient load to verify the circuits integrity.

HVAC 30A, 4WD 15A, HVAC 1 10A, BRAKE 10A, TBC RUN 3A.

Check circuit 300 ORN for battery voltage when the ignition key is in the RUN position.
Check for battery voltage at the rear fuse block under the rear seat Connector C1 pin D9.
If battery voltage IS NOT present at these locations, check for voltage at the ignition switch pin G for circuit 300 ORN.
If battery voltage IS present at the ignition switch pin G, check circuit 300 for an open.
If battery voltage IS NOT present at the ignition switch pin G, replace the ignition switch. Note: This PI does not apply to the Saab 97x. The 97x has a unique ignition switch location and an electrical harness. With this new switch, the electrical center pin designations and the ignition switch connector is different. In the event the concern above is experienced in a Saab 97x, circuit 300 can be checked for integrity using the appropriate schematics in eSI. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
------------------------------------------------------------------------------------------------------------------------------------------------

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Posted on Apr 29, 2011

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1 Answer

I have a '99 dodge grand caravan se, while in park the abs light came on, the battery light came on, and the check engine light has been on,


Looks like you have a few issues there.

1. The battery warning. This is indicative of a weak battery and if your battery is 3 years old or more I would replace it.

2. If you have a weak battery this can trigger other warning lights in the vehicle, typically the ABS warning but sometimes other warning lights as well depending on the electronic features in the car. If you replace the battery this should correct the battery warning and most likely the ABS warning if both of these warnings appeared at the same time.
Normally, once the ABS warning is displayed the anti lock braking system(ABS) will be shut down. Whilst your braking will be normal, if you brake too hard and lock up your wheels on a slippery road there is no ABS assist to prevent the brake lock up which you have when the system is working.

3. If the alternator on the engine is not generating sufficient power and thus not charging the battery at all, or very little, you will likely get a battery warning light. I don't know if your 1999 vehicle has a warning light to indicate a faulty alternator or not.

4. Check Engine Light.
You suggested the CE warning has been showing up for a few days and before the battery and ABS warnings popped up.
The CE warning can be caused by dozens of different engine issues.
The vehicle needs to be scanned with the appropriate scan tool to see what fault codes the onboard computer is generating because if you have a CE warning light there will be fault codes generated 99% of the time.

Once these fault codes have been pulled the mechanic can start to diagnose the cause of the problem or problems. Each engine fault code your car's computer is generating can be caused by different types of problems so it is important that they diagnose the issues correctly. Otherwise your Check Engine light will remain on as long as the causes are not identified and fixed.

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When I had that problem with the emergency light it was the sensor for emergency brake
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91 Buick park avenue abs light. This happened after my friend was driving down the freeway and his tire blew. Now it just blew the rubber off and he was able to drive t off the freeway on the belts. And...


ABS LIGHT AND MODULE TROUBLESHOOTING:



Anti lock brake system light comes up when there is issue with car brake systems. It can be low brake fluid or faulty ABS fuse or its issue with brake system or assembly. Your vehicles brake system needs inspection.


To troubleshoot these issues, I suggest you to refer the help links provided below. There are direct links with accurate solution, for these specific issues.


Click the link below and follow the procedure: ------


All types of ABS LIGHT / brake problems and repairs

http://howtobyme.blogspot.com/2011/11/abs-and-service-light-comes-on.html

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http://howtobyme.blogspot.com/2011/11/abs-light-stays-on-but-brakes-work-fine.html

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http://howtobyme.blogspot.com/2011/11/vcs-and-abs-lights-go-on-and-off.html

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http://schematicsdiagram.blogspot.com/2011/06/abs-and-traction-control-lights-stays.html

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http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

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http://whoisbyme.blogspot.in/2012/07/battery-light-and-abs-light-on-dash.html

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http://howtobyme.blogspot.com/2011/12/sometimes-abs-light-comes-on-while.html

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How Anti-Lock Brakes Work?

http://technoanswers.blogspot.com/2011/11/how-anti-lock-brakes-work.html

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Brake System Troubleshooting?

http://technoanswers.blogspot.com/2011/11/brake-system-troubleshooting.html

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Anti-lock brake light stays on all the time?

http://technoanswers.blogspot.com/2012/01/anti-lock-brake-light-stays-on-all-time.html

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ABS light comes on and Car makes Grinding noise?

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2008 Toyota Highlander: ABS warning light Blinking and OBD Error codes Coming?

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2003 Lexus ES: VSC, TRAC OFF, ABS lights ON?

http://technoanswers.blogspot.in/2012/04/2003-lexus-es-vsc-trac-off-abs-lights.html

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http://schematicsdiagram.blogspot.in/2012/02/can-i-drive-car-without-abs-fuse.html

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http://schematicsdiagram.blogspot.com/2011/12/where-is-abstcs-module-located-on-2005.html

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These details will help.

Thanks.

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1 Answer

My abs light on my 2000 buick lesabre will not shut off i have replaced rotors and pads what could the problem be


The warning light indicates that there is a malfuction in the anti-lock Brake System (ABS). Normally the system will then cease to function so you have a conventional braking system with no anti-lock feature to engage if you lock up the wheels on braking.

This ABS fault warning has nothing to do with the condition of the pads and rotors so renewing them, which is essential for good braking performance, will not solve the problem.

You will need to take the vehicle to a mechanic with the correct equipment to diagnose the cause of the ABS warning. It may be as simple as a failed ABS sensor (or sensors) and that is what I would be checking first.

It is quite safe to drive the vehicle with the ABS disengaged because your brakes will operate normally. What you don't have is the ABS kicking in to release the brake pressure temporarily in the event you brake hard and lock up any of the wheels.

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3 Answers

THE ABS LIGHT STAYS ON


HAVE CAR ABS BRAKES CODE SCAN.BECAUSE WHEN ABS LIGHT IS ON.YOUR CAR ABS BRAKES NOT WORKING.CHECK ABS BRAKES FUSE AND RELAYS.IF ALL IS GOOD.HAVE DEALERSHIP OR GARAGE CHECK ABS BRAKE SYSTEM BECAUSE ABS BRAKE UNIT IS PART OF THE BRAKE MASTER CYLINDER IF KEEP DRIVING COULD END UP WITH BRAKE FAILURE.CAR NOT SAFE TO DRIVE WHEN ABS OR ANY WARNING BRAKE LIGHT APPEARS.

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1 Answer

It shows an ABS light and check engine soon light but mechanics say everything is ok


HAVE VECHICLE SCANNED I HAVE SEEN IF ALTERNATOR VOLTAGE OUTPUT DROP TO 11.0 VOLTS THAT WILL CAUSE ABS AND CHECK LIGHT TO COME ON.DRIVE BELT COULD BE SLIPPING.BUT TAKE CAR TO AUTO ZONE OR ANY AUTO PARTS STORE THEY WILL SCAN CAR FREE TO SEE WHAT CAUSING CHECK ENGINE LIGHT TO COME ON.ANY TIME WARNING LIGHTS TURN ON SOMETHING WRONG WITH CAR.IF AUTO ZONE OR AUTO PARTS CANT SCAN FIND PROBLEM TAKE CAR TO DEALERSHIP LET THEM SCAN VECHICLE.BECAUSE WHEN ABS LIGHT COME ON ABS BRAKE SYSTEM NOT WORKING THE ABS UNIT IS PART OF THE MASTERCYLINDER WHICH IS THE PART MAIN PART BRAKING SYSTEM.

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2 Answers

ABS warning light What does this mean?


Means your anti locking brake system is disable, when the ABS light is on means the ASB computer pick up a bad signal from one of your ABS sensor's, any auto parts place like autozone can do a free code reading, once you get the code get back with us here at FixYa so we can help you diag. your trouble code, also your brake will work fine it be like a car with out ABS, get it check out.

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2 Answers

My abs light is always on and now my brake warning light is on but brakes seem to be working fine


The ABS light is a warning that you have an issue with the ABS system. The red brake warning lamp is serious. It is telling you that there is an issue with the base brakes. Your car will be ok with an ABS light, but the red warning lamp could be really dangerous. You should have them checked ASAP. It could be from many causes. A park brake switch, low fluid, the causes are too numerous to list. Please for your safty have it checked. Good Luck

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2 Answers

At various times all the warning lights go on/off


transmisson replacement is necessary.
thanks.

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