Gm abs troubleshooting

1. I would not be concerned because if there was a failure in the ABS you would definitely get an ABS warning light and the ABS and most likely the stability control/traction control systems (with added warning lights) will all switch off .

2. You can test if the ABS is operational. On a very quiet damp surface, straight, wide road( with NO other cars around), apply your brakes hard from a very low speed - up to 20 mph ONLY driving in a straight line - until the car stops. The front brakes should attempt to lock up under hard braking and if the ABS is operational you will feel it kick in and the brake pedal will pulsate as the ABS constantly allows brake pressure and then releases it to prevent the wheels from locking up on the damp road. If the ABS does not kick in be ready to release the brake pedal quickly to allow the wheels to rotate so you can steer the car safely. Without the ABS the front wheels should begin to lock up on the damp road surface due to the low level of tire grip. ONLY test this at very low speed and ONLY when driving in a straight line on a straight section of wide road with no other vehicles around.

Here's a guide for your ABS brakes Harvey. Repair Guides Four Wheel Anti lock Brake System Diagnosis And Testing...

Check all wheel sensors for broken wires, loose connectors or position of sensors in their mounting brackets.

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 issue,i suggest you to refer the help links provided below.There are direct links with accurate solution,for these specif issue.

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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ABS light stays on but brakes work fine?

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

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VCS and ABS lights go on and off intermittently on Lexus? http://howtobyme.blogspot.com/2011/11/vcs-and-abs-lights-go-on-and-off.html
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The ABS and Traction Control Lights stays ON dash of car? http://schematicsdiagram.blogspot.com/2011/06/abs-and-traction-control-lights-stays.html

------------- ABS & Brake lights warning indicator steady on dash and speedometer not working for Dodge Ram?

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

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

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

http://repairhelpcenter.blogspot.com/2012/01/abs-light-comes-on-and-car-makes.html

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ABS trouble codes for all models?

http://repairhelpcenter.blogspot.com/2011/11/abs-trouble-codes-for-all-1994-00-acura.html
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2008 Toyota Highlander: ABS warning light Blinking and OBD Error codes Coming?

http://technoanswers.blogspot.in/2012/05/2008-toyota-highlander-abs-warning.html

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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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2008 Toyota Highlander Hybrid: Warning Lights Abs, Vsc & Brake Are On?

http://technoanswers.blogspot.in/2012/04/2008-toyota-highlander-hybrid-warning.html

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ABS & Brake warning lights remains steady on dash? http://schematicsdiagram.blogspot.com/2011/12/abs-brake-warning-lights-remains-steady.html



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Can I drive the car without ABS fuse connected? http://schematicsdiagram.blogspot.in/2012/02/can-i-drive-car-without-abs-fuse.html

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Where is ABS/TCS module located on 2005 Cadillac Deville

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

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ABS motor keeps running? http://schematicsdiagram.blogspot.com/2012/01/abs-motor-keeps-running.html

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When the car stops, abs pump turns ON? http://howtobyme.blogspot.com/2011/12/when-car-stopsabs-pump-turns-on.html

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Replacing ABS unit on Buick Century? http://technoanswers.blogspot.in/2012/02/replacing-abs-unit-on-buick-century.html

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2008 Toyota Tacoma: ABS causes Brake pedal fade? http://technoanswers.blogspot.in/2012/04/2008-toyota-tacoma-abs-causes-brake.html
-------------- Toyota Camry: Premature ABS Actuation? http://technoanswers.blogspot.in/2012/04/toyota-camry-premature-abs-actuation.html

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How to replace ABS Modulator Control Unit on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-replace-abs-modulator-control.html

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How to replace ABS Pump Assembly on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-replace-abs-pump-assembly-on.html

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How to remove ABS Accumulator on Acura Integra?

http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-abs-accumulator-on-acura.html

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How to remove ABS Control Unit on Acura Integra?
http://repairhelpcenter.blogspot.in/2011/11/how-to-remove-abs-control-unit-on-acura.html

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These details will help.
Thanks.

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.

There's a service bulliten about that problem with rust build-up on the front hubs pushing the sensors out of posistion [ most common on the pickups in areas that use road salt ], it happens mostly at very low speed. The best way to find out the problem is to have the system scanned.

One of the sensors has gone bad and needs to be replaced, the other thing to that would also do that is the ABS sensor is dirty or needs to be re gaped to the speed ring on the hub. There was a issue bulletin with your Tahoe on the ABS activating under 8 km/h. Good luck and hope this helps, if not clean out the sensor with brake parts cleaner and check the wire harness and ABS sensor bracket. Re gap the sensor to the speed ring hub. Here is the bulletin. Anti lock Brake (ABS) Activation at Low Speeds (Clean Wheel Speed Sensor Mounting Surface) #03-05-25-007C - (05/16/2006) 2001-2006 Chevrolet Suburban, Tahoe

pull the fuse for the ABS system. problem fixed.

that is what it is desgined to do - reduce acceleration and apply the brakes intermittently when the wheels spin. You have a switch you cn push to disable it. You need to disable each time you start car. See owner manual.

06-10: Traction Control 1996 Contour, Mystique Workshop Manual
DESCRIPTION AND OPERATION Traction Control System The optional traction control system is designed to control wheel spin when accelerating on slippery or loose surfaces. Traction control system is available only with anti-lock brakes. The traction control system includes the following components:

• Hydraulic control unit.
• Throttle control actuator (9N825).
• Traction control switch.
• Traction control warning indicator.
• Front brake anti-lock sensor (2C204).
• Rear brake anti-lock sensor (2C190).

The traction control system operates as follows:

• System functions by transferring torque from the spinning wheel to the wheel with the most traction.
• This is achieved by applying the brake at the spinning wheel through the hydraulic control unit or reducing the throttle opening.
• Traction control braking and throttle control occur at vehicle speeds up to 50 km/h (30 mph).
• At vehicle speeds above 50 km/h (30 mph), only throttle limiting control is used.
• If speed control is operating when traction control system engages the traction control system will disengage speed control through the use of a speed control relay. This action is the same as applying the brake pedal with speed control engaged.

1996 contour
Traction Control Switch The traction control switch is located on the instrument panel, left of the steering column.

depending on the system if it is 2 channel or 4 channel one of the sensors that are located on the backing plate located behind calipers is eithier faulty or dirty you can try brake cleaner these sensors use a small magnet pickup device to sense when the wheel "locks up"