Brakes having an episode 🤦🏼‍♀️

Hoping for a little enlightenment. Had my p38 4.6 v8 1998 Auto for just over a year. She’s had some issues, but after being sorted she’s been fine. A few months ago I pulled up in the shop car park and turned off the engine as I usually would and was greeted with a very loud buzzing. I popped the bonnet to try and locate it and it was coming from the fuse box. Having no idea what I am doing I whacked the fuse box and buzzing stopped. Roll forward to last week and had the buzzing again. Pulled lid and couldn’t see anything untoward going on. Yesterday went to out to my daughter school meeting and my brakes didn’t want to work. Foot went nearly down to the floor before slowing. 3 lights on dashboard pop up, ABS, TC and brake ( usually the handbrake light. ) Carried on slowly and tried brakes again, same issue, tried again and they were back. Continued the 20 minute journey to school without further hiccup. On the way, happened many more times. Spoke to my local garage who have always been brilliant and they said it was a “ Spec list issue “??? Looking at other threads though, I see talk of accumulator replacement. Am I being fobbed off??

Buzzing in the fusebox sounds like a dodgy relay to me

Engine off, ignition on, how many pedal presses before the pump runs?

Relay 17 powers the ABS Hydraulic pump. Check if that's the buzzing, although it should not be on with ignition off ?

kermit_rr said:

Buzzing in the fusebox sounds like a dodgy relay to me

Engine off, ignition on, how many pedal presses before the pump runs?

Click to expand...

Trouble I’m having is it isn’t every time I use it Monday had no issue at all. Yesterday was terrible but the first time it’s happened. Just been out now and started her up and the brake is firm as it should be and the lights all went out after a few seconds of starting.

As above check the relay first.

Could also be the pressure switch mounted on the pump. One of mine went intermittent back in Aug last year, where the switch didn't always engage. Quick tap with hammer or large spanner started the pump.

Ended up buying a complete 2nd had pump & switch on eBay for £140, although I only swapped the pressure switch !! The pressure switches alone are generally £160 used, & new are generally unobtainable.

pwood999 said:

As above check the relay first.

Could also be the pressure switch mounted on the pump. One of mine went intermittent back in Aug last year, where the switch didn't always engage. Quick tap with hammer or large spanner started the pump.

Ended up buying a complete 2nd had pump & switch on eBay for £140, although I only swapped the pressure switch !! The pressure switches alone are generally £160 used, & new are generally unobtainable.

Click to expand...

The pressure switches can be found on other models, SAAB & Jaguar come to mind.

Relay changed today. As soon as I turned the ignition on it sounded like the pump kicked in. I’m hoping that’s to depressurise the system. Taken her out for a run for a good hour and touch wood, she’s stopped every time. Ridden the brakes a little more than I usually would. Popped open the old relay which definitely smells a bit burnt. I’ve got a spare relay in reserve in case the pump is on the way out and makes it burn out again. But I can’t thank you all enough for the help.

Rebellacey said:

Relay changed today. As soon as I turned the ignition on it sounded like the pump kicked in. I’m hoping that’s to depressurise the system. Taken her out for a run for a good hour and touch wood, she’s stopped every time. Ridden the brakes a little more than I usually would. Popped open the old relay which definitely smells a bit burnt. I’ve got a spare relay in reserve in case the pump is on the way out and makes it burn out again. But I can’t thank you all enough for the help.

Click to expand...

Have a look at the contact points inside, sometimes they can be cleaned but if they are titted and pitted they're done! Well played

Hopefully the pump pressurised the system!

kermit_rr said:

Hopefully the pump pressurised the system!

Click to expand...

I have a feeling they’ve been on the way for a while now as the brake seems much better than before, though that could be more in my head then reality

Rebellacey said:

Relay changed today. As soon as I turned the ignition on it sounded like the pump kicked in. I’m hoping that’s to depressurise the system. Taken her out for a run for a good hour and touch wood, she’s stopped every time. Ridden the brakes a little more than I usually would. Popped open the old relay which definitely smells a bit burnt. I’ve got a spare relay in reserve in case the pump is on the way out and makes it burn out again. But I can’t thank you all enough for the help.

Click to expand...

How many pedal presses between pump runs?