Avalanche Abs Activating

[divetrucker]

Hi,

 

I have a "02 avalanche 2500 4wd Auto 8.1L

 

Recently the ABS keeps activating at low speed even when braking gently on dry roads.

 

No warning lights are coming on and the ABS light goes off after 2 secs when I switch the ignition on, as per normal.

 

Any suggestions?

[glacialbass]

Are you sure it's ABS coming on? Is the pedal kicking back at you? It may be the Hydroboost valve as well.

[Kirkathon25]

it is a factory recall on the wheel bearings, they wont replace them though, i had to do both of mine when they started doing that, they would vibrate when coming to a stop.

[ChevyTech77]

Quick and simple, clean the wss to hub mating surfaces until you have at least 350 ac mv of output from both sensors while spinning the hub bearing flange by hand.

[divetrucker]

I think its the ABS. The pedal vibrates in just the same way as when the ABS does activate properly.

 

The hub bearings are involved here? Do I have a worn hub bearing then?

 

or,

 

WSS = wheel speed sensor that is mounted on the back of each hub?

 

I should pull them out of the hubs and clean them?

 

How do I measure the sensor outputs??

 

Do I connect a multi-meter across the ends of the WSS wire at the connector?

[preist]

Divetrucker - how did you resolve this? I've got exactly the same thing on my 02 1500 Sierra (abs goes off at low slowing speed, no dashboard light, kind of scary...)

 

Appreciate knowing if the cleaning suggestion worked out easy enough for you

[asc08]

There are numerous threads on this, a common issue. Generally, remove, clean and re-install the Wheel Speed Sensors on the front hubs. Check the voltage as mentioned prior to and after the procedure. do a quick search and follow the steps outlined.