G'day, all! Title says it all. I've had some issues over the years with brake light & occasionally the ABS light activating upon application of brakes. Yesterday, hopped in the car & as soon as I hit the brakes- pedal to floor, no pressure build-up, not good! I have both the Haynes manual & the workshop manual (NZ published). Neither is of any use on the subject, but it's safe to say the accumulator ball is junk. I've been perusing threads on the subject, seeming to find some conflicting info on currently -available what fits what. I know I'm past due a fluid flush & refill, also. Last year, Upon initial application, front brakes seem to activate first until pressure builds, then the rears. Needless to say, it didn't get driven much. I'm trying to get right to the problem without hours of stumbling around in an attempt to find concise troubleshooting procedures on this thing. I'd be eternally grateful to be directed to such info if someone could redirect me to it! Thanks in advance, stay healthy , all! Jerry

 

Hi Jerry,

The BRAKE lamp and ABS lamp may or may not be related to the same cause. A problem with the accumulator can cause the BRAKE and ANTI-LOCK lights to illuminate. A problem with a wheel speed sensor is probably the most common cause of the ABS warning lamp. Check your VCM for the Fuel Fault 68 (FF68) code, which indicates a problem with a wheel speed sensor.

As far as the accumulator goes, see this recent thread where members have offered some helpful info:

https://www.jaguarforums.com/forum/x...lm1907-223027/

My other suspect is your master cylinder. When the accumulator can no longer store sufficient pressure, you may get a hard pedal but I don't think it will go to the floor. That is more common with master cylinder failure or a fluid leak at a caliper or elsewhere.

See the Power Hydraulic System manual I am attaching for some diagnostic flow charts.

Cheers,

Don

 

Thanks for the info, Don! After reading & giving it some thought, You are likely right about the master cylinder. Pedal to the floor, then the accumulator pump pressurizes the system then I have some braking power. ABS light comes on only briefly during application of brakes. No loss of fluid anywhere, but it is pretty dark, so a thorough bleed & refill is in order. It's not unexpected that after 26 years, sitting for half a year annually, that the master cylinder may have gone ****-up. I do have a constant-on check-engine indication, which codes out to an EGR fault (no vacuum to EGR valve, it stops at the small solenoid upstream that controls vacuum to the valve). The thread you referred to I did read yesterday, there seemed to be some conflicting data in there, but I shall revisit that to see where I may have misinterpreted something. (it was early a.m., so it's possible). Thank you much for your help,as usual!

 

Get a new master cylinder, this will cure your problem with the brake pedal going to the floor

 

That shall be the plan. I'd not initially suspected the m-c due to the uniqueness of these systems compared to the conventional vacuum booster systems, which I wish these cars had. Thanks for the reply!

 

Try a good bleed first maybe, air in the system will cause the pedal to sink too.

Larry

 

And my saga continues. Having replaced my accumulator with a new WABCO unit the brake pedal goes all of the way to the floor with my car
sitting and not running. After starting it takes several minutes for the red brake light to shut off and I have a good brake pedal.
When the car sits the brake pedal goes to the floor. This tells me the brake master cylinder is bad and I have replaced several over the years.
New master cylinders (JLM805) are readily available and reasonably priced.
Is there anything special I need to be aware of in changing the brake master cylinder?
Is it easily removed from the power brake servo (JLM804/JLM1556)?
Thanks

 

Did it do this before you changed the accumulator? Sounds like you need to bleed your brakes again.

Larry

 

That's what I think, going to bleed again (3rd time).
I had good brakes before the last accumulator crapped out.
I've changed these accumulators in the past and never had these problems bleeding the brakes.
This accumulator is significantly larger and the additional capacity could be the problem?

 

Apologies for late reply. It may be beyond that, it's been acting up for a while. May just give it a go though, less p.i.t.a. than changing the master cylinder!

 

In the event a thorough bleed/fluid change doesn't help(doubt it will), can you or another forum participant recommend a reasonably- priced, reliable source for one? I suspect it may be cheaper to source one from across the pond, considering what some used parts are priced in the states. Opinions & experiences welcomed!

 

Usual failure of a master or slave cylinder is caused by pitting, which allows fluid to seep past the plunger or corrosion in the cylinder which abrades the plunger, with the same result.

It is not impossible to repair the cylinder using JBWeld and a hone if you are meticulous. I don't know if there's a rebuild kit for this master cylinder available, been quite a few years since I rebuilt one.

Still think bleeding might be the way to go, Pick up some speed bleeders, a lot cheaper and far less work than doing a master cylinder unnecessarily (!)

That way you can be sure no air will get sucked back in when you do the bleeding and IMO speed bleeders are a good investment anyway you look at it.

Larry

 

I shall give it a go, bleed whole system, as the fluid could be who knows how old? It's a bit dark in the reservoir, so it's past its lifespan for certain. Weather must cooperate, no garage space. A cold, occasionally wet crappy week in store here. Thanks, Larry, stay safe! Jerry