Freelander 1 1.8 Petrol Crankshaft sensor

Is there a "how to" on ABS unit reconditioning?

Interestingly, in the service record I have, the ABS unit on my car has previously been replaced by a unit provided by a previous owner...

rob_bell said:

Is there a "how to" on ABS unit reconditioning?

Interestingly, in the service record I have, the ABS unit on my car has previously been replaced by a unit provided by a previous owner...

Click to expand...

Hi Rob, a full recon is not really a job you can do at home, however, you can still do a hell lot ! - best way is to buy a cheap unit from a breakers and strip and check it then store it for parts - you will get all you need from that and can store it to replace parts on yours or to replace the whole thing. You can get a good unit for around 25 - 30 quid and they are getting rarer all the time so get them while you can. The stuff you can do are to fix any failed solenoid, fix motor issues and also shuttle valve signalling issues. you could also replace the high pressure piston units but they never go wrong really. all the wabco units on the freelander (Motors are all the same - solenoid housing covers are all the same and the shuttle valve switch sensor cover.) - to remove and replace the motor - also the end of the motor has an offset shaft (a bit like if you looked at a big end journal on a crank end on - that a sealed ball bearing mounts on to. This alternately pushes the 2 HP pistons in as it rotates in an offset manner. The bearing outer contacts the pistons and so pushes each in and releases once per revolution. That bearing can cause issue and can be replaced - I have not done it myself (yet) but it looks straight forward - you can see the bearing on the offset output shaft at the end of the motor in the pics. This can start to get tight and cause excess motor current and 'sticking motor' errors.
To replace the motor though you have to release the HP pistons as one is always compressed with the bearing and motor in place - once the motor is removed the hp pistons both spring to their uncompressed locations making motor replacement impossible. This is quite easy to sort though as there are two large threaded end caps on each side that once removed allow the hp pistons to be pushed back slightly - or out completely (no worries and no damage at all to the seals) - this then allows the motor and offset bearing to be replaced and then you push in the HP valve assembly with your finger and screw the end caps back - no seals or gasket or anything required.
Other area that cause issues is the 'shuttle valve assembly'. This is not the actual shuttle VALVES themselves which is beyond the scope of home repair and parts could not be got anyway (and they never fail in reality) it is the shuttle valve switch plate that fails (It consists of two spdt micro switches with a couple of resistors on each switch - when BOTH switch are closed the resistors pass a certain current that the ecu senses, when both are open the current is different, if only one is open then the current is different again - using this method the ecu can sense the position of both valves) - sounds complex but is not and is really easy to replace.
The valve solenoid cover is also worth removing when checking it over so the valve stems can be cleaned and also the solenoids. Removing the cover is straight forward but you MUST remove the shuttle valve plate and connector BEFORE removing the cover else you will rip the shuttle valve electrical transfer piece out of the housing !!
The other common failure is a single solenoid - that is easily fixed if you get a spare cover off another unit (from any model car with the same shape unit!)by cover I mean the solenoid cover plate - this contains all the solenoids (8) and the external connector, it is in a dry area of the modulator - again - easy to do but you MUST remove the shuttle valve switch cover and connector first or you will rip the shuttle valve electrical transfer piece out of the housing !! - it is easier than it sounds.
This is only for the wabco unit on the freelander Mk1 1.8 and 2.0 L series <2000 !
It is actually quite simple to do and 100% of all issues can be sorted by the user.
Faults that can be fixed

Common error codes

pump failure (monitor line)
shuttle valve switch (SVS) long term supervision failure
one sticking SVS
SVS electrical supervision failure
shuttle valve switch failure
Pump defect pump failure
pump sticking
Solenoid failure (any of 8)

Basically you check, test and can replace and repair all the normal failures on the Freelander WABCO ABS modulator fairly easily.

If there is enough interest I can do a 'how to' thread with images ? including stripping of the main failure parts, replacing and testing of all actuators on the bench. ?

I think a how to thread would be very educational for the rest of us Joe!

GrumpyGel said:

Jeerpers, that's in a right state! Looking at the pics, I think you're right, only for the bin!

I've had the modulator 'go' twice on mine. Each time, as you say. it was the shuttle valves. I've been lucky both times and managed to get replacements from breakers here.

I found that the round electrical connector to the loom is a bugger to separate - it is supposed to lie horizontal, but water does get in, and stay in corroding the connectors! By the time I eventually separated it, I wasn't the happiest bunny. Then when my best efforts to minimise brake fluid spillage failed in epic proportions - well, there were quite a few naughty words that day !!

The last unit I got, the breaker literally cut the brake pipes with snips and crimped them - good idea I though - keeps fluid in the system which can be cleared out if need be, but stops any debris or corrosion inside the unit. It also meant that my old unit that I took off I sealed with those pipe stubs. so its sitting safely in the garage and I can get a replacement shuttle valve sent from UK when I order other gear to fix it with

Click to expand...

Hi GG and Rob,

In a way it is quite good as I get a complete new replacement unit and get to strip this down hence learning at the same time. Luckily I had already a good understanding of the ABS system especially the FL Wabco !! - both Grumpy and I have been discussing this one and the associated ecu for a while now and studying all the info available ..
So, yes, I will do a strip down and reassembly with images and also a 'how to test the electrical side of things' It will be in photo format but I will try and do a video of the process at a later date.
I will need to wait for the other unit to demo the solenoid cover removal and testing as the one I have is fecked - as you can see .. I can certainly start with the shuttle valve switch (where the SVC faults come from) and how to test it. I have just sorted the testing procedure with a multi-meter. really easy to do.

As for the Kernackered unit I have -under the solenoid valves it is not in too bad a condition - well - by that I mean good enough to strip and learn from (certainly not to use!. I have ordered yet another as well to simply strip and examine and either remove the common failure parts -Shuttle valve signalling assembly- motor - solenoid plate etc. Obviously if it is in good nick I will leave it on the shelf. Probably worth replacing the motor offset bearing as well as they are cheap and very important. So, I will have 3 - 1 scrap but great for hauling apart - have already learnt a ton of stuff from this and it all makes total sense. The other to replace this (free inc shipping) and also one I picked up from ebay delivered to here for 27 quid ! - all in. at that price it is worth getting just for the shuttle valve signalling assembly ! let alone the other goodies, and it might be a minter.. if it has any issues, it is money back anyway so win win.
Definitely keep your unit with clean fluid in Grumpy. ! and replace it from time to time as - as you know, it is hygroscopic..
I will sort some pics of removing the valve / solenoid cover assembly - it NEEDS to be done in a certain order otherwise damage will occur - if done correctly it is no issue. It also includes removing the shuttle signalling unit. The solenoid / valve stem assembly is a completely dry area - the motor and HP piston area is virtually dry with just the occasional dab of brake fluid to act as a bit of lube.
It is worth removing the solenoid cover to check for cleanliness and any other issues, and to give it a wipe over whilst in storage.

I just found out how to remove and clean the restrictor units on the input pipe / hp return circuit (Warning ! - special tool need - - very expensive ! (a small coarse wood screw for expanding a plastic puller located on the top of the restrictor) (seriously!) .... also explored what all the blanking plugs are for... It seems that the actual shuttle valves can be removed as well .. but I need a 3/8 drive socket with 6mm allen key end to sort that. Would be interesting to take a look even if they were never removed in practice.

Yes, - quite good fun - will get some piccies and description sorted.
Joe