RRC ABS Trobleshoot

Help! I’ve replaced front discs, callipers, hoses and pads, yet have multiple issues! I’m unable to get any brake fluid out of each calliper! I’ve followed the bleed instructions, but have Numerous issues: 1) I cannot get any fluid out of cct 1 and 2, I’ve used a pressure bleed system; I’m getting fluid out of cct 6 &4!. The pump is running constantly, and the brake pedal is solid. I’ve also bled the pump, the two valves on the ABS unit and get lots of pressure from the accumulater bleed nipple! I’ve no brakes at all including the rear, which I have also bleed - and get fluid out of the rear callipers. I’m at a loss; the brake pedal is very hard, with minimal travel and I’ve also tried bleeding with the nipples on the front callipers open and pumping the pedal - I’ve also checked the brake pedal pin which is not disconnected..... there is just fluid coming out of each front caliper as suggested on the RAVE instructions. At a complete loss - all suggestions welcome!

It sounds like you are having a normal ABS bleed incident. The pump running constantly means either there is a lot of air in there or the pressure switch is dead.
I am afraid you need to go back and start all over again. Bleeding the ABS has to be done exactly as it says in the manual, there are no tricks, shortcuts, special tools or magic that can help. I once used 15 litres of brake fluid bleeding my brakes. DO NOT be tempted to try and shortcut the procedure.
I can only speculate about what's what here but I would start by cracking the bleed nipples and see if anything comes out, re-tighten the bleed nipples then you might need to pull each caliper off and remove pads . Then push the pistons back, then gently apply some pedal and see if the pistons will move. If the pistons don't move you may need to completely remove the calipers and check the pistons haven't frozen (unlikely though that is). You could also open the bleed nipples and again using gentle pedal pressure see if you can get any fluid to come out, don't forget to re-tighten the bleed nipples. Next, start the bleed procedure again.

In brief; depressurise system, pump pedal to force air in to reservoir. Bleed front hydrostatic circuit (lower bleed nipples), then bleed hydraulic pump. Next bleed accumulator followed by hydraulic booster. Bleed the power circuit at each caliper, make sure you follow the instructions. Next up, master cylinder; note if the pump runs for more than 45sec there is a problem (leak, air, pressure switch etc). Last, bleed hydrostatic circuit, again follow the manual to the letter.

It is possible to bleed the brakes single handed but it is much easier with an assistant.
Lastly, don't be tempted to get to a point and think "that will do" I am afraid it won't do, brakes are kinda safety critical, if you aren't 110% happy and sure about the brakes send it to a garage that knows how this system works. If the pump runs for more than 45 sec from depressurised there is something wrong. For a normal start up, the pump is supposed to run for approximately 20 sec, if it runs for much more there is a problem. Don't forget the accumulator may be at a point it needs replacement, it doesn't last forever.
Good luck with it.

HTH

Don't the front calipers have three bleed nipples one for the bottom pistons and the other two for the top pistons? They both have to be open at the same time to bleed. Having pressure at the pedal would indicate the system is partially bled. This info is from memory and it's a long time since I've owned a Classic.Just i remember having to buy two bleed pipes when i last did one.

Ok it appears that changing the callipers has allowed air into the ABS matrix (booster RTC6488)
Therefore now the system has to be plugged in to the diagnostic kit to open the valves in the matrix to allowing fluid to pass.
If it was just a simple fluid change of an ABS system as part normal service schedule, it would be done exactly the same as a no-abs system without any issues.

Diagnostic kit? damn - is this a specialist tooling system as the car is up on jacks with no brakes? I appreciate the advise BTW from you all as this is highly frustrating, I allowed the brake fluid to completely drain from the reservoir as I also changed the flex hoses and rear brake pipes. The pump just runs, noisily! if I open the bleed on the expansion tank the pump goes quiet, and if I also run the pump and then apply brake pressure the pump quietens down, but still runs constantly. Is there a way of resetting the ABS without the Diagnostic kit? to emulate a reset? as background, the car has bee off the road for a year undergoing lots of refurb, but she runs beautifully expect the )(*&^% brakes. I get no brakes at the rear either BTW.

You didn't say you let it run dry. Sounds like you have a bucket of air in the system. I understand what Discool is saying but I'm not sure if it is essential; time and much brake fluid should enable you to bleed the system through although I am not aware of a DIY method for activating individual valves/solenoids. That said, for ABS faults you can read the blink codes which the ECU sends via the ABS warning light on the dash. You need to faff about a bit to get the blink codes but it isn't really hard, again can be time consuming if there are multiple codes. Essentially you just need to pop out a relay and then bridge the abs plug. You will also need to have the table that tells you what the blink codes mean. The only other thought I have is whether or not your RRC has traction control which will add just another layer of potential messing about because you have to deal with the ETC valve block; I've not worked on ABS with traction control but as I understand it, bleeding the ETC valve block is carried out when bleeding the accumulator.
Realistically, all you can do is keep repeating the bleed procedure. I would also say get an assistant it will make it easier.

“I allowed the brake fluid to completely drain from the reservoir as I also changed the flex hoses and rear brake pipes”
Major work on the brakes then

What u need is a definitive answer from someone who has been in exactly in your situation with brakes.

But first in your neck of the woods in Kent there a few independent LR garages i would pop into to them for a chat... after if work u have done is 100% then it’s a fluid replacement... basically, unfortunately your RR has the Mk 1 of ABS systems so maybe it’s bit more involved in doing that, but the garage will/ should know all about it.

I would be very tempted to return to non-abs and rebuild the braking system...
My disco’s abs only activates when braking on snow or ice so not very often so i would miss it if it was removed, my old RR was to early to have abs.

Folks - not made any progress so have resulted in disconnecting all lines from the brake master cylinder; and still have little brake pedal travel, certainly would have expected lots of travel and wholly feeling! Have run pump (certainly now quiet). No excess of fluid coming from the master cylinder! AM I GOING DOWN THE WRONG PATH? As to proceed and remove the master cylinder looks like a nightmare task!

...oh, and have removed the ABS relay, but cannot find the 4pin socket for bridging the ABS...anyone point me to what that looks like and where it should be?

Sorry I Never had ABS on any of the tour Classics I had.

Seeking help; Background - no ABS! After some restoration, and brake pipes/calipers/discs/ hoses replacement, unable to get ANY brake fluid out of the Master Cylinder on the ABS side. Have troubleshooted as follows:
- Replaced ABS pump.
- Have bleed as per RAVE, noting no brake fluid on ABS side.
- Have removed ABS Relay, and attempted to reset all codes (constant 2-3, not sure this error code)
- Have removed both ABS lines from Master Cylinder 24(NSF) and 23(OSF).
- Operate pump ignition on, no fluid from these two outlets, pump runs constantly.
- Note; also have. SOLID brake pedal, no real movement beyond brake switch (and have checked the Clevis pin etc is on the brake pin).

Questions - Is there a solenoid inside the Master Cylinder that could be seized? is there a reset sequence? Observation -when I drain down the fluid, inside the reservoir at the rear there is a 2nd chamber, this does not drain out? this I believe is the ABS side of the reservoir, does this suggest a blockage/ seized?

Car has been idle for 18 months, much work done since - but this is really challenging me! HELP! Anyone had similar experiences and solved, or, is it typical for the Master Cylinder on the ABS models to fail?
and..any ideas of solutions vs replacement, and or replacement sources.

222ASH said:

Seeking help; Background - no ABS! After some restoration, and brake pipes/calipers/discs/ hoses replacement, unable to get ANY brake fluid out of the Master Cylinder on the ABS side. Have troubleshooted as follows:
- Replaced ABS pump.
- Have bleed as per RAVE, noting no brake fluid on ABS side.
- Have removed ABS Relay, and attempted to reset all codes (constant 2-3, not sure this error code)
- Have removed both ABS lines from Master Cylinder 24(NSF) and 23(OSF).
- Operate pump ignition on, no fluid from these two outlets, pump runs constantly.
- Note; also have. SOLID brake pedal, no real movement beyond brake switch (and have checked the Clevis pin etc is on the brake pin).

Questions - Is there a solenoid inside the Master Cylinder that could be seized? is there a reset sequence? Observation -when I drain down the fluid, inside the reservoir at the rear there is a 2nd chamber, this does not drain out? this I believe is the ABS side of the reservoir, does this suggest a blockage/ seized?

Car has been idle for 18 months, much work done since - but this is really challenging me! HELP! Anyone had similar experiences and solved, or, is it typical for the Master Cylinder on the ABS models to fail?
and..any ideas of solutions vs replacement, and or replacement sources.

Click to expand...

OK, let's see if we can work through this. I don't have a reference for an ABS error 2-3. You say it is constant? Have you actually cleared ALL the error codes. The ECU stores multiple errors and sometimes it can take a while to clear them all down. I assume you found the diagnostic plug and went through the blink code procedure, connect, disconnect, reconnect, disconnect - glad I haven't had to do all that for a couple of years now.

I would suspect a potential wiring fault. I can only suggest carefully checking all the wiring around the ABS relays and make sure the ground is clean and secure. An iffy earth will cause all sorts of odd faults.

I don't know what is inside the master cylinder and I suspect it is not a user serviceable part.

Did you check the caliper pistons could move freely? Maybe a bit after the event if you say with the brake pipes disconnected there is little pedal travel.
According to the workshop manual, there is no reference to reduced pedal travel. Increased pedal travel has a number of potential causes BUT the manual is quite clear that ABS components are not serviceable and if faulty, have to be replaced.

The reservoir at the back you say doesn't drain. This feeds the master cylinder and where you are at, the fluid in that chamber would be trying to go down the combined power and hydrostatic circuit. A couple of sticky solenoids are a possibility but if you say all the pipes have been removed then it suggests the master cylinder is faulty. There isn't much to that side of the braking system as far as I know (but I've been wrong before!).

Worst case is you may need to replace the master cylinder. These do come up on e-bay or you could look for anyone breaking a Range Rover Classic. Out of interest do you have a Haynes manual? The Haynes manual has a good section on the ABS system and I have found it more useful than the workshop manual. That's all I can offer for now. I'll have a look see if I can find fault code 2-3. HTH

Had a quick search, maybe have a blast on these:
https://forums.lr4x4.com/topic/26598-abs-fault-codes/
https://forums.lr4x4.com/topic/99869-1992-range-rover-classic-39-efi-2-door-abs-issues/
https://www.landyzone.co.uk/land-rover/rr-classic-brake-problems-abs.90038/

I'm sure there are plenty of other threads to do with RRC ABS issues. Good luck!

OK, I did find what I had in mind.

https://www.rswsolutions.com/index....odes/267-discovery-i-abs-blink-code-procedure

Note this relates to the D1. The system is slightly different but it has broadly similar characteristics and is also a WABCO system. Most of the codes are the same AFAIK although there is some difference in the hardware. Assuming the 2-3 code is the same I would be checking the relays, earthing and wiring in general. HTH.

Many thanks folks for all your support with this! I’ve ordered new relays, and have sourced a new brake master unit... I’m in this car for the long term and everything I’ve spent, might as well get it to the best I can... awaiting delivery of goods and will advise where I get to! Truly appreciate the wealth of experience on this forum, again many thanks for your support!... watch this space!

Hi folks- more help needed! I’ve swapped the master unit, but now different problems! No rear brakes although I’ve fluid at both callipers. BUT, can anyone please share either a photo if their unit (92 EFI), specifically which pipes connect to the accumulator, or a more detailed view of pipe connections to the master unit? The Manual is not clear and I’m wondering if I’ve swapped the pipes on the accumulator....all help gratefully received.

Sooooo, you've replaced the hydraulic booster unit. Simple enough. There is only 1 pipe connected to the accumulator, this is not likely to have anything to do with no rear brakes.

Now, as it happens the braking system is two in one. you have a HYDROSTATIC CIRCUIT and a POWER CIRCUIT.
The POWER circuit is rear calipers and upper pistons of the front calipers.
The HYDROSTATIC circuit is lower pistons of front calipers.

Are the rear calipers working? they commonly seize up. The other thing I have seen but was on a D1 is the small connector block on top of the rear axle stopping pressure getting through - don't ask for details it was long ago and I don't remember!!

Each port on the hydraulic booster is numbered, if you look at the ABS circuit diagram each inlet and outlet valve is numbered. That said, I don't know for sure if the the port numbers and circuit diagram correlate. The workshop manual also shows the routing for the brake pipes so perhaps pulling all these together will point you in the right direction.

If I get a chance I'll have a look and see what I can find viz pipe to port connections.