Hello Richard - the connector should be located on the forward end of the brake reservoir - there are three level switch contacts, mounted within the reservoir - one for the ECU (normally closed) and two for the brake light (normally open) - the black/yellow wire connects one side of the fluid level switch contact to the brake light - the black wire connects the other side of the fluid level switch contact to ground - if you unplug the connector, place a “shorting jumper” (such as a paper clip) to connect the purple/green wire to the white/green in the connector to allow the correct path for the ECU - (if your wiring has no problem, such as a stray ground) then the dash light should not be on (lighted, lit, glowing) - this test can be done with the ignition on with the engine running - if the light does not extinguish (not lighted, not lit, not glowing) then another source is activating the light (I can help you diagnose other possible sources) - advise of what result you gain after testing - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/17/2020 1431hrs. EDT USA.
Jim,
The accumulator celebrated it’s 1st birthday on 20 September. If what you say is true, your use of until, means what? Is there something I can do on my end? Is it safe to drive? That question came from my wife who is scared of the vehicle in the first place.
Hi.
I filled it yesterday and the light went off and will stay off until the level goes down a bit. We retired to rescue homeless and abused animals 20 years ago and we don’t travel much due to our responsibilities, thus this test will need to be done next week when we need supplies.
I would have to yield to others more experienced with the TEVES III. I certainly would not tell you it is safe or not safe. That is really a personal decision. As Kirby has pointed out in numerous threads about brakes…they are what stops you. If I had a manual transmission i might be more inclined to take on a steep hill. Regardless, carry a can of fresh brake fluid in the boot until resolved…in case you need to top up once you get to your friends…assuming you go
I was just pondering aloud to see what the experts might think. I know the accumulator has a rubber diaphragm with a gas(i think nitrogen) precharge of pressure. As brakes are used a little fluid is compressed into accumulator and accumulator helps maintain steady pressure for the ABS. I think.
Thanks for those words of wisdom, and I do keep a bottle of fluid in the boot even in the good times. Yesterday I noted while on the NYS Thruway the light stayed on for longer than normal. I took another route to get to his house but thought I would try the steep hill back as there was no traffic and I used the side of the turnpike, which thank goodness nothing happened and I made it safely home. The brakes are strong Jim and if the light didn’t come on, I would not know there was an issue. As mentioned, I can stop on a quarter.
Hello Richard - this is in response to your question about why the light may come on when the fluid level is not very low: the reservoir contains three fluid operated reed switches - two NORMALLY OPEN switches light the BRAKE FAILURE warning light if the level drops TOO LOW - the third NORMALLY CLOSED switch opens and signals the ECU if the level drops below a minimum level for full ABS operation - in this case the ECU switches off the front wheel ABS and turns on the LIGHT for the ABS warning - also, another reason is the combined pressure switch which contains three pressure operated switches - the two normally closed switches open when normal operating pressure is reached, thereby switching off the pump and the BRAKE FAILURE warning light - NOTE - the brake failure light will be on UNTIL the operating pressure is reached - the third normally open switch closes if the system pressure falls TOO LOW and signals the ECU, which then turns on the LIGHT for the ABS warning - just for clarification, is the illuminated light, on your instrument panel, marked as ABS or BRAKE - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/17/2020 1541hrs. EDT USA.
Hi again and thank you for your time.
The light on the dashboard is the red light, nothing else. I am going to enclosed a picture of the reservoir and if you will identify the three switches you speak of it would be appreciated.
Please advise and thank you in advance,
Rick
Hello Richard - as to the light in question - on the instrument panel, from left to right, there are five lights on the left upper level, then seven lights on the middle lower level, then five lights on the right upper level - the ABS light is the fifth light (from left to right) on the left upper level - the brake fail light is the center light (fourth light) on the middle lower level - I will go to my 1991 car and check the plug for you (I am thinking that it is the top big plug in your picture) as this should be the same on your 1989 car (the information in my service manual states that the 1989 and 1991 have the same circuit) - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/17/2020 1659hrs. EDT USA.
Hi again.
The only light that comes on is the red brake light. I know as I replaced all the bulbs over the summer procured from Paul Novak. It was quite an easy task!
Rick
Hello Richard - okay on understanding which light is on - yes I have the same connector plug as you show in your picture - as per the wiring diagram I have, of the connector plug, pins 2,3,4 & 5 are in use (even though there are five pins in the reservoir jack, there are only four connections in the connector plug - there is no connector pin number 1 on the wiring diagram since there is no number 1 pin in the connector plug) - with the condition of correct fluid level, referring to the normally closed contact (within the reservoir), pin 5 goes to the ECU and pin 4 goes to the combined pressure switch - referring to the normally open dual contacts (within the reservoir), pin 3 (common to both normally open contacts in the reservoir) needs to go to a ground and pin 2 (common to both normally open contacts in the reservoir) goes to the brake fail light - if you disconnect the connector plug, and place a shorting jumper in the connector plug between pins 4 & 5, this will let the ECU get the signal as if the fluid level was okay for the ABS operation - with the shorting jumper installed, while the connector plug is removed from the reservoir, there will not be any ground source for the brake failure light contacts - check at this point, of this testing procedure, to see if the brake failure light is extinguished - NOTE - if you have no brake failure light on at the moment, prior to disconnecting the plug and due to a full reservoir, then you can bring the brake failure light on by temporarily providing a shorting jumper between pin 2 & 3 of the connector plug (while you have the shorting jumper between pin 4 & 5 of the connector plug) - NOTE - if you remove the shorting jumper between pin 4 & 5 of the connector plug, the ABS light should come on - NOTE - at FIRST glance, the switch contacts may be not removable from the reservoir for cleaning or replacement - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/17/2020 1917hrs. EDT USA.
Hi.
I really appreciate your help in this matter. Being that it is dark and I have no garage and the vehicle can’t fit into my barn, I will need to pick up where I left off tomorrow. I will advise you of my findings.
Meanwhile, please give a thought to where the fluid is disappearing to. The light is one thing but missing fluid is the other part of the puzzle.
Rick
Hello Richard - just an added reference note - the Teves wiring diagram, that “lockheed1” posted reference to, is very similar to the service manual diagram that I have - the numbering of the reservoir connector pins are different, but the operation paths are the same - as to possible leak paths, I would suggest checking the areas that the other posters listed and try to eliminate each area - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/17/2020 2057hrs. EDT USA.
Good afternoon.
I had a friend help me and as far as he can see, everything you had us test is normal and working the way it should. Your input was valuable, once again thank you.
Now the “disappearing” brake fluid. We looked on the ground and inspected as much as we could see and feel and there doesn’t seem to be a leak. I do have a slight oil leak in the front which to me is normal for the age of the vehicle. I have an appointment with my mechanic this Thursday and the more information I can give him regarding the “disappearing” brake fluid will give him incite and less diagnostic time.
Rick
I missed the ‘accumulator’ in the post so apologies for that misinformation.
I would start checking the dust boots for fluid, however if you have already replaced a significant amount of BF then it should already be evident if a calliper is leaking.
Hi.
I won’t be able to get a true picture of the bottom until my mechanic puts it up on Thursday. I have no way to view it.
Rick
Hello Richard - now that you have tested the operation of the level switches for the dash lights, at least you should be able to trust them as being correctly advising you of a problem, so glad that was of help to you - once you are able to find the path of the “disappearing brake fluid” leak, please post so that knowledge will be gained - I am curious as to what you find (and probably others are also) - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/18/2020 1835hrs. EDT USA.
Yes I will post what I find, but in the meanwhile, and this goes for all who read this, please do not hesitate to chime in on the case of the “disappearing” brake fluid.
Thanks!
Rick
Regarding the amber ABS light and the Red Brake light - I may have missed it, but the ABS light seems to be missing in action. No one has mentioned that both the ABS amber light and the Red brake light should both be on (bulb test) when you first turn the ignition on, and should remain on for a period of time (engine started or not) until the brake pump builds up pressure. and the ABS and the Brake light go out as the required pressures are reached. If I remember correctly, the ABS light goes out first, and then the Red Brake light since each is activated at a slightly different pressure.
Hello Richard - as “lockheed1” mentioned, check the operation sequence of the ABS and Brake Fail lights upon initial ignition key operation - also, have you read the procedure for filling the brake reservoir of the Teves system - it is not just a “fill when low” condition(like it is on non-ABS systems - the pump is used during the fill procedure - do a search, on the internet, and then after reading and performing the correct fill procedure, do a periodic check for any loss of fluid - I am thinking that this may be why you are finding different levels when you check the fluid - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 10/19/2020 1052hrs. EDT USA.
Hi.
I think you might have touched upon something! First, the ignition sequence is per the manual…no issues. BUT…and I need read up on the filling of the Teves III system, I might be overfilling it. When it has become a tad low, I have topped it off when I should probably allow it to go down to a semi mid line then deal with it. There is no fluid on the carpet below the brake box in the cabin. By the by, I found I have been using synthetic dot 3 fluid. I know the vehicle doesn’t like synthetic oil and I only use conventional oil. I wonder if synthetic oil is a bain due to her age?
This has been a great learning experience.
Rick