ABS issue

[61_FL_Apache]

This is actually for the wife's 04 Chevy Venture van... but its in the same era of vehicles and hope my question is not too far off.

Over the last few weeks, the brake pedal has been feeling spongy and the ABS light will come on. When its acting up, the brake will go further down that usual and you can hear the ABS pump running.. When the ABS light comes on, the pedal feels fine, but the ABS system is not active. I put a cheap-o code scanner on it, but there are no codes..

No recent brake work. Any ideas? To me it felt like a worn out master cylinder, but I don't think so now. 69k miles on the clock.

Thanks for your help!!

[4x4toy]

If the truck is acting up during slow speeds, like 5 mph or slower, you probably have a speed sensor "dropping out". You need to find someone with a scan tool that can read wheel speed data. While driving vehicle at slow speeds have passenger hold scan tool and watch wheel speed data. The wheel that falls to 0 mph while others are still showing actual speed is the bad one. This is fairly common problem, and this will not set a speed sensor trouble code. Hope this helps.

[1FastBrick]

Need to use a real scanner and not a generic code reader.

Not sure about the venture platform but as mentioned you could have an issue with the wheel speed sensor.

On the trucks it's not uncommon to get a small amount of corrosion under the sensor base that lifts the sensor up so it wont read.


If the brakes are spongy you probably need to service the system. Brake fluid should be replaced as needed similar to an oil change. It's often overlooked on most cars.

[61_FL_Apache]

Thanks for the feedback.. I have a local mobile mechanic with a "real" scanner and im sure he can find it.. I was worried it was the ABS pump going bad, but I think it was reacting to a faulty wheel sensor.

[LT1 Burb]

Yep, speed sensor, change the hub.

[61_FL_Apache]

The speed sensor is a part of the hub? I thought I saw them listed separately.

[cstm68]

Sounds like the hub is goin bad and could have some movement, the in and out movement of a bad hub can cause the piston in the caliper to be slightly compressed and require more travel when the brakes are applied. As for the speed sensor, the abs tone ring is inside the hub, any bearing movement will cause the abs to act up. I would run a scan on the abs and that should tell you what sensor is not reading, 90% or hub assembly's come with a new and sensor wire

[LT1 Burb]

On my truck the hub had to be changed because I did the speed sensor but the part inside the hub was corroded and can't be cleaned so even with a new sensor it still did not read.

[61_FL_Apache]

Cool. Thanks guys for the input! I'll let you know how it goes.