ABS Brake Issues - Chevy Truck

Crusty

Crusty

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ABS Lights and alarm started going off a week ago, took my 2003 Chevy 2500HD to the shop and said fix it. Brakes were functioning fine, just a sensor issue right? Annoying at worst.

ABS Sensors were replaced, was told drive it around a few days and the system will reset - ok simple enough.

A week later and now the ABS kicks in REALLY early and too soon when brake checking at even 20 mph and worse....sometimes it doesn't kick in and the last part of the stop, my truck will roll 5 feet like the brakes were lost / went soft.

What is going on? ABS was not set correctly?
The break-in period is not over yet?
I'm screwed? Shop fucked up?

Talk to me folks....somebody here knows the problem or had same issue.

Thanks,
 
ABS actuator controller is shot.Time to find one and that part is discontinued..
 
Crusty said:
ABS Lights and alarm started going off a week ago, took my 2003 Chevy 2500HD to the shop and said fix it. Brakes were functioning fine, just a sensor issue right? Annoying at worst.

ABS Sensors were replaced, was told drive it around a few days and the system will reset - ok simple enough.

A week later and now the ABS kicks in REALLY early and too soon when brake checking at even 20 mph and worse....sometimes it doesn't kick in and the last part of the stop, my truck will roll 5 feet like the brakes were lost / went soft.

What is going on? ABS was not set correctly?
The break-in period is not over yet?
I'm screwed? Shop fucked up?

Talk to me folks....somebody here knows the problem or had same issue.

Thanks,
Click to expand...

First, you need a new mechanic.

Not a parts changer, someone that knows how to Diagnose a vehicle!

What codes are in it? Do you have a code reader?

Let's start with the basics.
 
Amazon is delivering a Scanner tomorrow.
A few calls into Parts Yards to see if they have the ABS Control and Modulator Valve assembly in stock.
 
I have 2 of them and both are somewhat intermittent. Was hoping it was a ground issue. I haven’t found a local place that rebuilds them and there not cheap!
 
It's been a while since I worked for GM, but I remember seeing front hub reluctor wheels cracking and rotating on the hub that would cause all sorts of odd abs events and never setting any dtcs. Pull the sensors out and see if you can spin the reluctor wheel with a screwdriver through the hole. A damaged tooth on the reluctor wheel will cause the same thing. Early on those sensors would generate an AC signal that you could measure with a dvom just by spinning the wheels by hand, that was the method called out in the service manual to find a sensor signal that was dropping out. ***You could also use a modern scanner in graph mode to possibly see which sensor is dropping out during a road test.*** I havent personally seen an abs module cause this but I suppose its possible. Are there any dtcs associated with this issue? Sensor signals dropping out too soon may not necessarily set a dtc, an open circuit would for sure but not just a signal. The abs module has the ability to detect an open circuit but not signal strength, a loss of signal strength usually means the wheel is locked up and it will initiate an abs event. Of course the problem may be something else entirely it's difficult to diagnose it without putting my hands on it. It's been many years since I've had to diagnose such an issue.

It doesn't do you any good now, but I had a new in box abs pump and control module for early 2000s 2500 truck in my garage for 20 years, no one wanted it at the time so I threw it away perhaps a year ago :rolleyes:
 
KLC said:
It's been a while since I worked for GM, but I remember seeing front hub reluctor wheels cracking and rotating on the hub that would cause all sorts of odd abs events and never setting any dtcs. Pull the sensors out and see if you can spin the reluctor wheel with a screwdriver through the hole. A damaged tooth on the reluctor wheel will cause the same thing. Early on those sensors would generate an AC signal that you could measure with a dvom just by spinning the wheels by hand, that was the method called out in the service manual to find a sensor signal that was dropping out. ***You could also use a modern scanner in graph mode to possibly see which sensor is dropping out during a road test.*** I havent personally seen an abs module cause this but I suppose its possible. Are there any dtcs associated with this issue? Sensor signals dropping out too soon may not necessarily set a dtc, an open circuit would for sure but not just a signal. The abs module has the ability to detect an open circuit but not signal strength, a loss of signal strength usually means the wheel is locked up and it will initiate an abs event. Of course the problem may be something else entirely it's difficult to diagnose it without putting my hands on it. It's been many years since I've had to diagnose such an issue.

It doesn't do you any good now, but I had a new in box abs pump and control module for early 2000s 2500 truck in my garage for 20 years, no one wanted it at the time so I threw it away perhaps a year ago :rolleyes:
Click to expand...

This man knows how to Diagnose. 👍🏼
 
My truck is lifted on 35s and it became too dangerous to let the abs decide when I can brake, so I pulled the fuse on it like many others did, and lived happily ever after. I'm not worried about locking them wheels up.
 
Chingon619 said:
My truck is lifted on 35s and it became too dangerous to let the abs decide when I can brake, so I pulled the fuse on it like many others did, and lived happily ever after. I'm not worried about locking them wheels up.
Click to expand...
What fuse?
Did that turn off the ABS alarm and Parking brake lights?

The ABS system is currently disconnected and so right now stops are not an issue.
 
Crusty said:
What fuse?
Did that turn off the ABS alarm and Parking brake lights?

The ABS system is currently disconnected and so right now stops are not an issue.
Click to expand...
My truck is a 2000 so not sure how different it may be but the ABS fuse prevents the ABS from kicking in. Both brake lights are on in the dash but I just ignore them. No alarms that I know of.
 
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