Hi,

Just thought I would post this up as I couldn't find any information on this particular error but I understand that it's common problem.

For about 2 years the low-pressure light has been on almost constantly on my face-lift XJS.

It turns out the issue is in fact the reservoir.

They fail and the fluid doesn't flow properly causing a low pressure warning.

The part number is JLM12202 and appears to be almost non-existent supply wise.

Just wanted to put this up in case anyone else has had this issue.

Currently on the lookout for one but as with any second hand part you run the risk of buying another faulty one.

 

Jaguar XJS Brake Master Cylinder Reservoir 1989 1996 | eBay

???

Looks to be the part you need?

 

Hiya,

Yep, I saw that one as well.

The listing is slightly misleading, the one fitted to my car is almost triangular in shape, I believe this one was fitted to the cards up to '94

Which is why it's so damn difficult to get hold of! haha.

The email I got back from one company was interesting in that it mentioned an almost identical system was installed onto the X300's. But haven't had chance to look into this yet. The reservoirs I've seen look the same but you only need one mounting point to be wrong and you've wasted your money.

Here's the piccy (item 4)

Part no. JLM12202 | Reservoir parts from Jaguar Classic Parts UK

 

What exactly is wrong with the reservoir? Does it have a hole in it and is leaking brake fluid everywhere? Or is it just the switch inside the reservoir? Have you checked the continuity at the connector? If you have open circuit between the pins when there is sufficient brake fluid in the reservoir, then the switch is bad.

Yes the exact same brake master cylinder was used on all 95-97 X300's. But the reservoir is a slightly different shape. It may still fit in the XJS, it mounts to the reservoir in the same fashion so mounting would not be the issue just space for the reservoir itself. You should be able to easily find a used one on Ebay or the like.

 

According to the garage report. There is an open circuit in the sensor which is causing the low pressure sensor light to stay on.

Looking at the reservoir part image, it appears the sensor is part of the reservoir itself? So not sure you can actually repair it.

 

On my X300 the sensor looks to be inserted in the bottom of the reservoir and glued in place. Not sure if it can be replaced?

 

I don't want to be "that guy" but I got in this thread expecting an oil pressure topic....Are you talking about a Low fluid sensor? The reservoir isn't meant to be pressurized

 

I thought the same thing. I think the OP meant low level and not low pressure.

 

On my '92 l also get the low brake fluid warning light now and then....but it matches the fuel, no fuel readings, temp. and other weird warnings. Guess l must clean all the contacts sometime....

 

The reason why I wanted to put this post up is that I understand it's a common problem with the sensor becoming corroded and causing the light to stay on.

In the manual and service manual it's referred to as the "low brake pressure warning light"

Just wanted to put this up because forums and sites talk about changing pressure switches and parts of the brake system when in fact it's just the stupid sensor in the bottle gone bad! haha.

I used to own a Citroen that had a similar sort of problem, it had a sensor to tell you if the windscreen washer bottle was near empty. The notorious hard water in the Thames Valley area used to attack the copper tabs on the sensor, so every six months I pulled the sensor out rubbed it down with some wet and dry and replaced it back again.

I'm not sure how buried the sensor is in the Jaguar reservoir bottle but I assume the acidic nature of the brake fluid has over time attacked the contacts.

 

Did you ever resolve this? My 95 XJS has same problem and can get a new reservoir but cost is close to £300!

 

Merely a kibitzer.


1. My 83 XJ wuzza six has a plastic reservoir attached directly to the iron MC. It has a clever, but pesky, little float and contact points.
It is merely a low brake fluid level warning device. Mine has a busted
contact spade and defies my efforts to fix it.


2. My 94 Jeep has a similar device. Quite a bit more robust. never seen a warning come on it's alarm panel.


3. The low windshield washer fluid level comes on in text from time to time. As it seldom freezes around here, I usually top it off with water and a mild detergent.


So, is your issue, the float or the wires back to the warning lamp?


And, yeah nomenclature is murky at times...


Carl

 

Hey,


It's a little while since I'd looked at my post and then all of a sudden I get some replies


Greeban where on earth did you find one?! I tried everywhere.


I found a supplier in the US but of course with the reservoir being on the other side of the car it wouldn't fit on a RHD car. Was about $90 if I remember.


I suppose if you were feeling brave you could dismantle it and move the sensors across but it looks like a pretty hefty sealed unit.


I did have a close look at the reservoir but because of it's construction the sensor appears to be almost sealed within a tube. So getting to it is pretty tough. I think there's a float in there that obviously rises or falls.


At the moment the light is pretty much on all the time


I kind of got side tracked from this as just afterwards both sides of the car were badly keyed so I'm now trying to save up the necessary money to get the car repainted.

 

You do understand that the following is not at all correct, right?

'fluid level' and 'fluid pressure' are unrelated.

 

SNG Barratt have some and also have a pattern to make new ones. They are expensive at 225+VAT so am waiting to see if they manufacture some more and so perhaps can reduce the price a little.

I may treat myself this Christmas to a new one, who knows, but in the meantime I have disconnected the sensor so the dash light is off - I know it is a safety feature but as it is almost always just me in the car I am willing to live with the tiny risk until I find a reasonably price replacement. I regularly check under the bonnet as I love to look at the engine and now I have a good reason to do it more often!!

 

I fitted one of these, also fed up with the price and poor durability of the OEM reservoir, excellent quality, much better and does not leak fluid.
2 Chamber Brake Fluid Reservoir - Car Builder Solutions - Kit Car Parts and Accessories
Greg

 

Thanks for this info - I did consider this route myself but wanted to try and keep as original as possible; did you fit this remotely or can it be attached to the top of the cylinder in same way as OEM reservoir?

 

Apologies, as you did not mention your model and year of manufacture, as far as I could see anyway, I assumed you had a pre ABS car from your description. The link I posted is not a suitable replacement for JLM12202
Greg

 

No worries - it is a late model with ABS; I guess I will just have to 'suck it up' as the Americans say. The car is in for an MOT next month so if it fails on this at least I can get a replacement and keep driving.

 

Just a quick update for those that may be interested.

I purchased a new reservoir from SNG Barrett (thanks for the info Greeban as it's not listed as available on the website but they do have it in stock).

I removed the clip on the sensor plug; removed the plug and put it to one side.

The existing reservoir is held in place by a pin but due to the age of the mounting (or possibly just the way it was installed at the factory) it wouldn't budge at all. I was worried that too much effort would break it and being a Saturday afternoon and everything on Guernsey would mostly be closed I didn't want to damage it!

I used a small syphon pump that I use to change diff oil with and sucked out as much of the brake fluid as possible from the reservoir. You could if you wanted take the drivers side wheel off and bleed the fluid through the calliper there to get the level down if you wanted to.

Using two small bladed tools I gently prised apart the two nylon lugs that go either side of the pin and then with a little force pulled the reservoir free from the rubber bushes. There was some small fluid spill but I had a nice large bucket of soapy water ready to wash down any engine bay that got touched by the brake fluid (very important if you don't want paint damage!) I had two towels on the front wing just as a bit of added protection.

The rubber seals looked fine condition wise. I rubbed a small amount of clean engine oil with my finger onto the connectors on the new reservoir, really just to aid the insertion of the new part.

I positioned the new reservoir and made sure everything lined up and like above I gently prised the nylon lugs either side of the pin and then pressed down until the reservoir slotted into position. Obviously I was very gentle with this as I didn't want to break it!

Once the new reservoir is on the car I filled up the reservoir with fresh fluid.

I hadn't touched the brakes throughout this so I there was no need to bleed the brakes again and the light has now gone out, and everything is fine! Yay!

Considering the light has been on and off for two years I'm glad to get rid of it! haha.

Apologies for the confusion with the original post title. I know that it was a low fluid sensor but the manual refers to it as a "low pressure light" so that was how I started it.

Anyway job done


....next job is the headliner and then to start saving for the new paintjob