Bleeding Antilock Brakes

[AirForceAngler]

I'm planning on flushing and bleeding the brake system on my '00 Silverado. Is this done any different with ABS or is it just like regular brakes? Thanks in advance for the help.

[GnatGoSplat]

Bleeding is the same as long as no air gets into the ABS modulator.

If that happens, you will have to have the dealer run a Tech 2 bleed sequence on it.

[Jersey Tahoe LT]

Could air in the madulator cause the ABS to engage just before I come to a stop? How much does that Tech 2 Bleeding sequence cost? Thanks in advance.

 

Later,

Brandon

[Ben]

Could air in the madulator cause the ABS to engage just before I come to a stop?  How much does that Tech 2 Bleeding sequence cost?  Thanks in advance.

 

Later,

Brandon

There is TSB to fix ABS initiation on OBS. Don't think NBS has this problem. Issue is ABS sensor gets rust underneath and gets bad ground. Sensor disappears during low speed braking, so ABS computer thinks tire is skidding...so initiates.

 

Other is brake fluid on friction materials. Causes grabby behavior...no fix other than to change out the frction materials.

 

NEVER bleed the calipers via "C" clamp method with out opening the bleeder screws. Pushing the old stuff backwards into the ABS valve area will min require tech tool to open ABS valves to bleed to ruining the ABS valves ($$$$ replacement).

 

[edit]...forgot to list buddies personal Suburban/GM Truck help/info site. Freebie, so price to pay is pop ups.. #1 Son's Suburban/GM Truck info/help site Then go to the TSB section to look up the ABS TSBs.

[Jersey Tahoe LT]

Well I looked at the site and found nothing in there TSB area. But I went to all Data and found nothing for the Tahoe but the 1999 Yukon 4x4 has a ABS sensor TSB. Why would Chevy not? It is the same thing. How can I talk to a dealer about this. Or at least find out what the TSB symptoms are?

 

Later,

Brandon

[Jersey Tahoe LT]

Here is the GMC TSB #

 

02-05-25-002 JUN 02

[Ben]

Well I looked at the site and found nothing in there TSB area.  But I went to all Data and found nothing for the Tahoe but the 1999 Yukon 4x4 has a ABS sensor TSB.  Why would Chevy not?  It is the same thing.  How can I talk to a dealer about this.  Or at least find  out what the TSB symptoms are?

 

Later,

Brandon

Original thread on another forum

 

TSB #02-05-25-006A - (11/26/2002) and there's another that haven't been able to find text: 99046B SERVICE BRAKES, HYDRAULIC:ANTILOCK

 

 

Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface) #02-05-25-006A - (11/26/2002)

 

Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)

1999-2000 Cadillac Escalade

 

1995-1999 Chevrolet Silverado (Old Style)

 

1995-2000 Chevrolet Suburban, Tahoe (Old Style)

 

1995-2003 Chevrolet Astro Van, Blazer, S10

 

1995-1999 GMC Sierra (Old Style)

 

1995-2000 GMC Yukon, Yukon XL (Old Style)

 

1995-2001 GMC Envoy, Jimmy

 

1995-2003 GMC Safari Van, Sonoma

 

1995-2001 Oldsmobile Bravada

 

This bulletin is being revised to change model information. Please discard Corporate Bulletin Number 02-05-25-006 (Section 05 -- Brakes).

 

Condition

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

 

Cause

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

 

Correction

Measure AC voltage and clean wheel speed sensor mounting surfaces.

 

Raise the vehicle on a hoist.

Disconnect both the front wheel speed sensor harness connectors.

Place a DVM across the terminals of each sensor connector.

Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.

If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.

Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.

Clean the speed sensor mounting surface on the hub to remove rust and corrosion.

 

Important

Make sure that the sensor sits flat on the hub. If the sensor flange is distorted, replace the sensor.

 

 

Apply a thin layer of bearing grease to the hub surface prior to sensor installation.

[AirForceAngler]

Thanks for the help! I surely would have "c-clamped" the calipers back without opening the bleeders as that's how I've done it on older cars.

[Jersey Tahoe LT]

I have done the C-Clamp thing. Nothing happened luckilly. Will never do it again. Called the dealer. $150-$160 for TSB Service. Without the replacement of anything. I will be attempting this on my own this weekend. Doesn't seem that hard. I will let you all know how I do.

 

And thanks for posting that Info.

 

Later,

Brandon

[Ben]

Also make sure to replace the bleeder screw caps.

 

Water gets in there withOUT the caps. Once in there, rust...

 

When bleeder is opened later, NEVER seals and allows air bubbles in.

 

Only resonable fix is replace caliper or cylinder. Guess you can remachine the seat surface, but then the bleeder screw will go too far into the casting....