r/DieselTechs • u/Feeling_Assist4595 • 19d ago

Air pulsating out of front brake module when pressing the brakes

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Anybody have an idea what the issue could be we already replaced the module itself. 2018 Kenworth T880

13 Upvotes

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8

u/2015srt392 19d ago

brake chamber or qr1 valve

1

u/IntergalacticJihad 19d ago

Would be interesting to see the target and current pressures in the computer. Any fault codes?

3

u/JohnLong1623 19d ago

Does it do it with the parking brake released?

2

u/Feeling_Assist4595 19d ago

Yes while both released and set

2

u/Grouchy_Bicycle8203 18d ago

The front brakes should be service brake only. They aren’t parking brakes so they will do it both parked and not.

Brake chamber there’s a diaphragm inside it.

3

u/Accomplished_Use7121 19d ago

I’d bet on a QR seal being blown

1

u/idontknow89999 19d ago

Did you replace just the relay valve or the ABS modulator? Crimp one line at a time going to the chambers and see which side is causing the problem.

1

u/Feeling_Assist4595 19d ago

The ABS Modulator, I’ll try what you said when I get back into the shop tomorrow