Briefly:

21 relates to the Main Valve in the Actuation Unit which operates when ABS is required.

The other codes relate to the front left and right ABS sensors at the hubs.

I'll send you the document tomorrow to further explain.

Also remember, the test only shows the first of each series of codes. For example, you might also have 22 and 23 as well as 21. But until you resolve 21, it won't show you 22 etc

Paul

 

Hi N Bath

Did your Mechanic Bleed the Low Pressure Side of the System when he Bled the Brakes?

As if not then that could well be your problem

 

I’ll try that, and see if it helps.

I’m a novice at best, but I think there might be two issues which I’ll have a look at later in the week:

1) One of the sensors is malfunctioning (hence the fault codes).

2) There seems to be little elasticity in the system, so that the accumular charges more quickly than ideal and can’t store much energy. Perhaps it will fail in due course.

Would love to hear everyone’s thoughts. I’m just guessing. I’ll try and bleed the system, as that certainly seems like an easy thing to try first.

 

Now that I think about it, I can’t figure out why I can push the pedal all the way to the floor with the pump on unless there is air in the system.

I’ll definitely give the brakes a bleed, but if I shouldn’t follow the instructions in the manual, I’ll search around for the right ones.

 

Hi N Bath

Although I've only just touched on this, in case you came back and said that your System was different in some way, if you don't Bleed the Low Pressure Side then trying to Bleed the Calipers would more often than not turn out to be a Complete waste of time, as there is always going to be Air Trapped in the System

This is the Full Write up that I did years ago, although its not quite as dramatic and as Scary as it seemed back then, except to say it was one of my First Posts!

Bleeding the Low Pressure Side of the Teves MK11

In a 'Nutshell' you pull out the Spring Clip that holds the Pipe with its 'O' Ring out of the Brake Pump and then let the Brake Fluid Flow Free, until the Brake Fluid is running Clear of Air Bubbles (Takes just a Few Seconds!)

Then reconnect it 'On the Fly' while the Brake Fluid is Still pouring out of the little plastic elbow that you have pulled out

(1) Don't let the reservoir ever run dry or else you will have to do this all over again!

(2) Don't break the Plastic elbow just in case you can't get another one anytime soon (which you probably cannot)

(3) Spray the Plastic Elbow with WD as you gently rock it back and fourth while trying to pull it out

(4) If you lose your Nerve at this Point, you could instead try pulling the Braided Pipe off and then using a Syringe to try and top it up before putting it back

(5) Once the Brake Fluid is running Clear, Push the Plastic Elbow back in the Brake Pump while the Brake Fluid is Still Running

(6) Its going to make a mess, so have plenty of Rag around to mop up any Spills

(7) have a Bucket of Soapy Water Standing by, to dilute and then wash away any Spills

(8) Don't let any Brake Fluid get on the Paintwork or it will Strip it in an Instant!

(9) Then Bleed the Brakes like Paul (ptjs) Showed you

If you want to Test the Valves in the Master Cylinder Actuator before you do so and which you may also be able to do while its still attached to the Car, see this next thread Testing the Valves in the Valve Block

Do not attempt to remove the Valve Block from the Side of the Master Cylinder Actuator, to have a look inside (have a look at my Photos instead)

Start up procedure on my Car:

(1) Turn the Key to position (1) or maybe position (2) (can't remember!) All the Dash Lights Come on including the Yellow ABS Light and the Red Brake Light

(2) At this stage you can hear the Brake Pump Running and the Red Brake light will go out before the Yellow ABS Light

(3) It will take about 45 Seconds before the Yellow ABS Light goes out but even when it has gone out, it may take a Few Seconds more before the Brake Pump Stops Running, so make sure it has Stopped Running before you attempt to Start her (this has nothing to do with the Bleeding Procedure!)

(4) During a Normal Start Up don't touch the Brake Pedal until the Pump has Stopped Running and all the Lights have gone out

Don't let the Brake Pump run for more than a Minute absolute MAX without allowing it to rest for a Couple of Minutes in Between 45 Seconds is about Normal

 

Out of interest, why don’t you just bleed the low pressure side from the pipe that attaches to the elbow rather than the elbow itself?

 

Hi N Bath

The Low Pressure Side is Brake Fluid 'Gravity Fed' from the Reservoir to the Brake Pump

Then once it has entered the Brake Pump it becomes 'The High Pressure Side' and so I doubt if that would work

Although you could try and Bleed the Low Pressure Side by pulling off the 'Braided Pipe' instead

Mixed Results doing it that way, sometimes it works and sometimes it doesen't

 

Took a long lunch and had a look at the right front sensor, the outer coaxial wire is damaged, if it wasn’t completely cut through, it is after I had a look at it. Does anyone know if that outer coaxial wire is a shield or carrying signal?

I’ll repair that, then do a low pressure bleed, and see how I go. Any more thoughts out advice are welcome.

 

Hi N Bath

A Damaged Wheel Speed Sensor, could be Symptomatic of your problem, as I believe you mentioned that apart from the Dash Light the Brakes were working OK

(1) Preferably get a New Wheel Speed Sensor or repair the one you have

(2) Don't Bleed the Brakes (at this stage) there may not be any need!

(3) On a Short Test Drive somewhere Safe See if the problem persists (everything might be ok now)

(4) You may need to go over 20 MPH to reset the System

(5) If you've got the Road Wheels off for any reason (Check for Sticking Brake Pads) if they feel too tight in their Calipers, you can always Shave a bit off each side of their Metal Backing Pads with a Sander/Grinder like some of us do (hot tip from Greg)

Shaving down Brake Packing Pads if they feel too tight in the Calipers

 

I’ve ordered a new (used) wheel speed sensor from the UK, will be a couple of weeks before it arrives, will let you know how that goes.

 

New cable arrived from the UK, it’s from an XJ40, perfect fit and length, but I have a few issues fitting it:

1) I’ve got the old sensor out easy enough (the cable was trashed, so I cut it), but to thread the new one through the same place, I will have to remove the disc shield. Anyone done that before? I got stuck when it came to removing the central bolt holding it on place. I couldn’t get a socket over it, and couldn’t get enough leverage with a spanner. Am I missing something?

2) The XJ40 grommets and bushes are in a different place on the cable, has anyone had any luck sliding them? I spent a good 20 minutes trying to move them and they wouldn’t budge.

Any help much appreciated.