RRC brakes and ABS

[duncmc]

I should have said that if you try to unscrew the pressure switch from the pump body with it still attached to the inner wing, you may well break the rubber mountings. The mountings fall apart easily. It would be best to try to use a big monkey wrench or something to stabilise the pump.

[spiker3]

thanks guys,

lots of great info and photos. I will try to do the checks you mention this weekend. will let you know how I get on.

[spiker3]

Hi,

Done a bit more testing over the weekend here are the results:

I ran a wire from the battery to teminal 87 of the relay and the pump came on. Hopefully this means that the relay and the pump wiring is ok.

I then tried to test the pressure switch. This is where I am not too sure if I tested correctly. With the ignition on I tested the top right pin and bottom right pin of the 5 pin connector with a multimeter, there was continuity. The "jump the pins" part was a bit confusing for me. I had the ignition on and ran two wires one from the battery to the top right pin and the other from the top right pin to the bottom right pin. Nothing happened. Was I doing this correctly? If I was does this mean that the only thing left that can be at fault is the ecu itself?

Things seem to be one step forward one step back but I am ready for the next step throw it at me!!

[duncmc]

Hi,

Done a bit more testing over the weekend here are the results:

I ran a wire from the battery to teminal 87 of the relay and the pump came on. Hopefully this means that the relay and the pump wiring is ok.

I then tried to test the pressure switch. This is where I am not too sure if I tested correctly. With the ignition on I tested the top right pin and bottom right pin of the 5 pin connector with a multimeter, there was continuity. The "jump the pins" part was a bit confusing for me. I had the ignition on and ran two wires one from the battery to the top right pin and the other from the top right pin to the bottom right pin. Nothing happened. Was I doing this correctly? If I was does this mean that the only thing left that can be at fault is the ecu itself?

Things seem to be one step forward one step back but I am ready for the next step throw it at me!!

Yes, looks like the wiring from the relay to the pump and the relay itself is good from your first test.

Unfortunately you did not do the other bit properly. Sorry, my fault for not being clearer. You are trying to simulate the pressure switch being closed and creating a continuous circuit. So just take one wire, and run it directly from the top right pin to the bottom right pin. You don't need to involve the battery. However as you have continuity across the corresponding pins on the pressure switch, the switch is doing the same thing. So it is looking likely that your ecu may be faulty, or the wiring to and from the switch.

Please can you redo the tests at the switch, paying careful attention to getting the correct pins as I descibed before, just to recheck.

[spiker3]

Hi duncmc,

I have just re read your reply that contained the photos. I must have been concentrating on the photos as I missed the important part in the brackets "(not the bit on the switch above)". I had been putting the wires on the switch, sorry about that. Just gone out now and put the wire across the top and bottom pins of the multiplug that fits onto the switch. The pump ran!! Does this mean we have found the culprit, the pressure switch??? If it is the pressure switch I will go the landrover dealer in town tomorrow to see if they can order me a new one. The only spares place specialising in landrovers has already told me they dont stock any spares for the classic. I dont suppose a pressure switch from a disco 1 or P38 could be used??

Thanks.

[duncmc]

Great!

I think that does say that your pressure switch is faulty. The easiest way to check next would be to subsitute for another.

I got one here for £20 from a scrap yard.

The pressure switch from a P38 is the same I think. You will need to bleed the system once you have swapped it.

[spiker3]

Hi,

Went to my landrover dealership today to enquire about ordering a new pressure switch. I hit a bit of a brick wall though, when the guy checked on the computer there did not seem to be a pressure switch anywhere. The hydraulic pump was there with a part number. The picture of the pump did not show any pressure switchand without a part number I was told there was nothing that they could do. Does anyone out there know what the part number for the pressure switch is? Then maybe I can go back to the dealers and make them order it for me.

Dunc, when you say I will need to bleed the system once I have swapped the pressure switch, do you mean the whole brake system or just the hydraulic pump?

Thanks.

[Bowie69]

I think the switch and pump come as a unit, if you can find one in a breakers yard, then I would do that.

[fozsug]

They have never been sold as a seperate item by Land Rover only with the pump. Best bet get one from a scrap yard , as has been said, thepressure switches are the same on P38's. If it has a part no on it post it up and i can try my local Wabco dealer.

[duncmc]

Unfortunately as others have already said, Landrover only sold the pump with the pressure switch as one unit. And I think Webaco is the same. So really the only option is a second hand one from a scrapper or a whole new pump, and the pumps are about £1000 here new.

As far as bleeding it goes, I would bleed the whole system after.

Why not try to see if you can get someone to recondition the pressure switch locally? Is there anywhere that services hydraulic plant equipment?

[duncmc]

Gumtree 4x4 currently have a brand new pump and switch on ebay for £375, but only 50 minutes left!

http://www.ebay.co.uk/itm/ABS-PUMP-STC885-RANGE-ROVER-CLASSIC-92-94-NEW-/170834981225?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27c68ef169

These are about the normal price for a new one, depending on your chassis number. http://www.ebay.co.uk/itm/ABS-Pump-Range-Rover-Classic-NEW-Genuine-Wabco-Unit-earlier-type-/400270887343?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5d320109af

I have had a look for part numbers on the switch and can only find the markings "At" and a number 134M2 which are both on the plastic terminal housing so that could be something?

[duncmc]

I have done some more searching/reading, and it looks like the pressure switch was probably made a company called ATe (now Continental Auto GbmH). And the best bit is it looks like the switch was also used in a lot of SAAB's! And you can still get the switch on its own new, or from a scrapped SAAB!.

http://www.rangerove...-failing-2.html

http://www.eeuropart...aspx?id=8994071

That has got to be usefull information for lots of us with ABS Range Rovers!!

EDIT!

Here is information about the SAAB ABS system in the 900, and where to locate the pressure switch.http://www.genuinesaab.com/psi/files/92-900-abs-diagram.pdf. From reading this third link and other ABS information on the RRC system, I am not 100% convinced that the two switches are identical even though they are very similar. The specification MIGHT be slightly different, i.e the pressures at which the switching occurs and I am not sure that the switch is wired the same. Could be worth a look though if you can find one locally and cheap. So don't just take my word for it. Read all this and make your own decision.

[spiker3]

Thanks for all the help guys.

I have only ever seen two other clasics here in Botswana in about the last 8 to 10 years so the chances of me finding a scrap pressure switch are less than zero.There is no Saab dealership in the country either so that could be difficult but if the switch is on most models it might be possible. I will try to check out hydraulic plant equipment companies.

My best bet though is probably to seek out a switch from a P38 and hope it works. I have a south African friend here who likes land rovers maybe he knows someone in SA that might know somone who has a spare.

If all that fails I will have to save up and buy a new pump and switch, this is definitely my last option.

A big thanks to everyone who has helped me try to solve this problem, especially dunc, it is much appreciated. It would have been so much easier if I lived in the UK.

I will let you know if I manage to sort it out and get the car back on the road.

[duncmc]

You are welcome, glad to try to help. I am sure that a P38 switch will fit, if you can find one.

Have you tried to contact a breaker in the UK to see if they can send you a switch from a scrap car? I am sure someone would.

[Snagger]

Have you tried cleaning the old switch up first? It might just have a bit of dirt trapping its plunger...

[spiker3]

Hallo again everyone,

I am having no luck in trying to get the pressure switch. I have sent dozens of e mails to breakers yards in the UK and in South Africa. I have contacted as many as possible garages i read in LRO international magazine. Of the few responses I have got I am being told I need the pressure control release valve part NTC9735. I am positive this is not the right part, am I right? I actually found a P38 range rover being broken up here in Botswana, the guy wanted £350 for the pressure switch, when I said it was too much the lowest he would come down was to £200.

Is there anyone out there that has a spare pressure switch they can sell me? I have someone in the UK where it can be sent to, then I can make arrangements to have it sent out here. I have had this car for so long now without being able to drive it that I am begining to think it would be better to get rid of it and stick to driving my Landcruiser. Something I dont want to do.

Thanks and fingers crossed.

[duncmc]

Hi Spiker.

A google of NTC9735 doesn't come up with anything at all. You sure that is the number they said?

Have you thought of the someone in the UK buying a used pump from ebay for you, then shipping that out to you or just the switch? Here are two on there now....

Pump and modualtor block for £95 +P&P http://www.ebay.co.uk/itm/RANGE-ROVER-CLASSIC-VOGUE-1994-WABCO-ABS-UNIT-PUMP-BLOCK-/320911159771?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4ab7cbb1db

Pump currently at £10 +£5 delivery to UK, and will send internationally. http://www.ebay.co.uk/itm/Range-Rover-Classic-Webco-ABS-Pump-/170846171487?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27c739b15f

If I was you I would contact the second one and see if they will post to you in Botswana. If not get it sent to UK, then on to you. Don't give up yet.

[spiker3]

hallo everyone,

I know its been a few months but just a little update on my rrc.

I managed on the third attempt to buy an abs pump off of e bay and had it sent to my parents in the UK. Unfortunately it would have cost the earth to send the pump out here to Botswana so they just sent the pressure switch. After waiting nearly three weeks for it to clear customs I finally got it last week.

I have fitted the switch and now have brakes, hurrah!! I also have a few more questions if anyone can help me?

when I turn on the ignition the pump only runs for 2 or 3 seconds, is that normal? Also when I drive the car (only on the dirt road by my house so far) the ETC, ABS and brake warning lights light up when I use the brake. Also the pump works. When my foot comes off the brake the pump stops and the lights go out. I am going to try to bleed the brakes will this help? I have heard bleeding the brakes can be problematic, I will follow the workshop manual to the letter but does anyone out there have any other tips or helpful advice.

Thanks from a very happy rrc driver (finally).

[duncmc]

Hi Spiker3.

Well done!

Normal operation should be;

When you turn the ignition on after not driving it for a few hours, or after you have fully depresurized the system ( ignition of and press the brake pedal fully for 30 times) the pump should run for 30-45 seconds or even upto 60 secs if something else is not quite right. Then after that when you press the pedal or the traction control or ABS operates it runs for short periods, maybe 10 secs.

Did you bleed the system after you changed the pressure switch? You should have done. But it does sound like you might have air in the system.

It can help when bleeding the brakes to raise the rear of the car a bit, and have plenty of brake fluid. And keep an eye on the reservoir, don't let it run out. Some parts of the operation you need two people, and follow the workshop manual instructions to the letter. Then you should be fine.

Good Luck.

[spiker3]

Thanks Duncan will let you know how I get on.

[spiker3]

hi,

I managed to get a friend to help me yesterday afternoon and we tried to bleed the brakes. everything seemed to be going well up to step 8 and there seemed to be quite a bit of air coming out. The problem started at step nine of the workshop manual (bleed the power circuit at four calipers in turn). The pump did not come on at all and when depressing the brake pedal little or no fluid came out of the bake calipers. There was also no pump for step 10 (bleed master cylinder). We carried on with the workshop manual instructions until the end. Now the car is back to how it was before, no pump and no brakes, only now the three warning lights(etc,abs and brake fluid level)stay on all the time.

We tried to re check everyrthing until it got too dark. The relays click, pressure switch tested ok and running a wire from the battery made the pump run.

One thing I wasnt too sure of was the last step no. 14 fully pressurise system. i assumed switching on the ignition would activate the pump and it would run to fully pressurise the system. Is that corrrect?

I dont know what to do now, did I not do a step correctly, should I repeat the whole bleeding process, or has something else gone wrong that I need to fix first?

[duncmc]

hi,

I managed to get a friend to help me yesterday afternoon and we tried to bleed the brakes. everything seemed to be going well up to step 8 and there seemed to be quite a bit of air coming out. The problem started at step nine of the workshop manual (bleed the power circuit at four calipers in turn). The pump did not come on at all and when depressing the brake pedal little or no fluid came out of the bake calipers. There was also no pump for step 10 (bleed master cylinder). We carried on with the workshop manual instructions until the end. Now the car is back to how it was before, no pump and no brakes, only now the three warning lights(etc,abs and brake fluid level)stay on all the time.

We tried to re check everyrthing until it got too dark. The relays click, pressure switch tested ok and running a wire from the battery made the pump run.

One thing I wasnt too sure of was the last step no. 14 fully pressurise system. i assumed switching on the ignition would activate the pump and it would run to fully pressurise the system. Is that corrrect?

I dont know what to do now, did I not do a step correctly, should I repeat the whole bleeding process, or has something else gone wrong that I need to fix first?

Can I check that at step 8, you pressed the brake pedal down and then turned the ignition on to get the pump to run? And did the pump run when you did that?

If it didn't run with the pedal down and the ignition on, something is wrong. The pump needs to be running to bleed the pressure circuits or you hardly get any fluid out when you bleed them.

I would do the whole thing again. Once you get the hang of it it doesn't take that long. I find it is easiest to take both front wheels off and put the front on axle stands.

[spiker3]

hi,

At step 8 the pump ran, it was at step 9 bleeding the power circuit that the pump stopped running. It did not run at any of the 4 brakes and little or no fluid came out from both back brakes.

Because I am bleeding the brakes on fairly level dirt outside my house I did not want to raise the back whilst bleeding the front brakes as I felt it might be unstable. would this hinder the bleeding process?

I will try to bleed them again this weekend if I get the chance.

Thanks

[duncmc]

You have something strange going on there then. I would re check your fuses and relays. Thats all of the fuses under the front seat, and check for dodgy connections and wiring. Has a fuse popped when the pump ran maybe?

[Snagger]

You might have an electrical problem of some sort. Does the pump run at all now? If it was allowed to run continuously for a long time, it might be damaged.

I think you need to replace all the fuses and relays associated with the system, just in case one of them is faulty. Unplug, clean and refit the connections to the pump and the pressure sensor (that means the two plugs - the black rectangular pressure sensor one and the white cylindrical pump power plug). Use contact cleaner and make sure the contacts are clean and bright, not dulled or corroded. Also remove the braided hose from the pump to the ABS block to make sure it isn't blocked - the pump may be operating correctly but be unable to pressurise the system. A similar issue would occur if the accumulator has failed - remove and drain it and check that its pipes are also clear.