Brake Question

[Rapidtransit]

I'm stumped about this situation concerning my brakes.
I've just replaced my 2 front hub assemblies. I did one side at a time 2 days apart. After I did the first one the brakes were fine with no brake pulse. After doing the 2nd one and taking the car for a ride, there was brake pulsing, like the ABS is kicking in. I took the wheel off and checked everything, and the installation was perfect. I did a ABS brake scan and there were no codes. The ABS light never comes on when this is happening. There's no issue with the rotors or pads. The caliper pistons are fine and move easily. I'm stumped, any help would be greatly appreciated.

 

[Kumba]

I'm stumped about this situation concerning my brakes.
I've just replaced my 2 front hub assemblies. I did one side at a time 2 days apart. After I did the first one the brakes were fine with no brake pulse. After doing the 2nd one and taking the car for a ride, there was brake pulsing, like the ABS is kicking in. I took the wheel off and checked everything, and the installation was perfect. I did a ABS brake scan and there were no codes. The ABS light never comes on when this is happening. There's no issue with the rotors or pads. The caliper pistons are fine and move easily. I'm stumped, any help would be greatly appreciated.

So it sounds like you need to look at the second hub assembly. Maybe it is out of round, flant bent, or not seated right. I wouldn't take much for the hub to be off to get pulsing on the pedal. I would see if you can exchange the hub and if the problem goes away.

If that doesn't solve it then I would start checking that brake rotor for out of round or runout. Might just need a shim to make everything happy.

 

[Rapidtransit]

Brake Update

After going over the install yet again, I thought a bit about this whole situation. I wanted to see if the problem was caused by an electrical or mechanical issue. I thought that if I disconnected the sensor it would shut down the ABS system and give me an illuminated ABS light. With the ABS system off, if there was no brake pulsing then the mechanical brake system is fine and it's most likely the sensor.
That's exactly what I did and the brakes work normally like a car without ABS, though the ABS system is shut down with the illuminated dash light. This eliminated anything mechanical short of an issue with the internals of the hub assembly that is read by the sensor.

 

[cammerfe]

Sounds like it's time to look at the sensor system. I'd focus on the reluctor. And if the hub isn't seated properly, you might have a condition that triggers the ABS.

KS

 

[Rapidtransit]

Finally Found The Problem

Over the last few days I switched ABS sensors and looked carefully at my wheel hub installation and couldn't find any issues that would point me to why the ABS pulses when applying the brakes.
My Actron ABS brake code reader does not reveal any defect codes.
I borrowed my son's OTC Genisys scanner and low and behold in the data stream, the front left wheel had a circuit malfunction trigger, but only faster then 4-5 mph. All this mind you with no ABS fault light illuminated.
I got a replacement wheel hub assembly and now everything is fine.
I wanted to take a look at the reluctor and after taking the back of the hub assembly off, I could see that one spot on the reluctor had a dent. This is what caused the ABS sensor to malfunction. I never would have thought of that. I guess its these peculiar times that a real scanner is what is needed to really troubleshoot the electronics.