Hi All, new to the forum but not the car. I’ve had my XR4x4 for 29 years and she was 10 months old when I bought her. We have history!

Always maintained myself.

For or several years I’ve heard an odd noise coming from the bulkhead like a wah wah wah but not always and I kind of ignored it as it seemed harmless. It may still be however...

I recently went out in the car (which only does about 500 miles a year) and noticed that when applying the brake the orange abs light lit and relays clicked behind the glove box.

Both these relays operate simultaneously when pressing the pedal. Interestingly they are both purple not one not one green and one purple as most suggest they will be. I’ve never changed one. I Opened them both up and operated them manually. Good contact across both sets.

Removed the ecu and did all. The resistance checks. Found as others have sail the 9&10 are only closed when system up to pressure as suggested by Haynes book.

During my testing that buzzing noise noise started and I found it is coming from the chamber on which the pressure switch is mounted. When the switch was disconnected it stopped presumably because the ecu detected a fault and ... well what I don’t know but it stopped. I assume this switch isn’t anything special is it?

Im wondering if what I’m hearing is pressure bleeding past a valve seat causing it to bounce and buzz?

Where red to go from here? I’m pretty sure that in the past I could press the pedal several times before the pump kicked in so I’m wondering if the accumulator has failed and is not storing energy? Could it be the pressure switch is bad causing it to stop pumping at loo low a pressure?

Is is there a way to measure the pressure. I’d see that as a good way forward. Any advice appreciated. BTW I swapped out. The abs ecu with one I picked up years ago for trouble shooting and it made no difference.

thanks all

Dave