Long Story Short

The Full Version with Photos will be on my 'Cherry Blossom' restoration thread in due course

Put 12 Volts direct to the Brake Pump I took off 'The Ice Princess' (1990 XJS V12)
result (No dice!) the Brake Pump wouldn't run

Did the same with the Brake Pump that I took off my Parts Car and that wouldn't run either

With the Pump removed from the Car, I then Tested the Output Voltage from the Plug that would normally be connected to the Brake Pump and got 0.36 Volts!

Hardly enough to light up a Torch Bulb!

I also checked and replaced the 32 amp Fuse in the ABS and the 32 amp Fuse in the Brake Pump, so why only 0.36 Volts?

Any ideas?

 

Is the pump completely removed from the car? If so, you have also taken the pressure switch out of the circuit, so the pump relay won't be triggered.

 

Hi Bladerunner

The Brake Pump kept blowing the 2 X 32 Amp Fuses for the Brake Pump and the ABS under the Passenger kneepad

So I took the Brake Pump out of the Car and then tried to test it by giving it 12 volts on to the 2 pin plug of the actual Brake Pump Motor and it wouldn't spin

The Brake Pump Motor appeared to be seized and so I separated it from the actual Brake Pump itself

Where while I could turn the Brake Pump part by hand, I was unable to turn the Spigot that was sticking out of the Motor

The spigot sticking out of the Motor Part of the Pump would not revolve even if I gently tried to turn it with a spanner

Any ideas as to what may be wrong?



Although the Pump (on the right of the pic) turned freely The Motor with the Spigot (on the left of the pic) would not turn at all and appeared to be seized up

 

Just to backtrack a bit, going back to the voltage at the brake pump connector, plug the connector back into the pressure switch, the blue plug, and you should then see 12v at the pump power connector.

As for the pump, if it won't turn then it is clearly dead - have a look at this link to the same kind of pump on a Range Rover: ABS Pump

If you can get into it, you may be able to do something with it depending on what's going on inside?

 

Does it have 0.36 before and after the fuse?

 

Hi Bladerunner

Genius!

Thank you so much for that Link, as now I think I know what may have happened!

Stuck Relay that didn't cut out, Motor Overheats and Fries all the windings and probably also melts those Plastic Brush Holders

Hence the reason the Motor Part won't even turn with a Spanner, it's Seized Solid!

Where getting inside that Motor is an 'almost' impossible task, as there are locking pieces that have been hammered in place, that would need a Hammer and Chisel to remove them

And even if I did so, finding spares to repair it, could not only be a difficult job but probably not worth the hassle

So no wonder it kept blowing Fuses if the Motor doesn't Spin round, which probably means there is nothing wrong with the Cars electrics

But if I try and Re-Test it by Plugging in the Pressure Switch on the Brake Pump, it will probably keep Blowing Fuses, as the Brake Pump Motor has Seized up

Unlike XJS's there are lots of places round my way that dismantle Range Rovers, so finding a Pump 'may' not be much of a problem

But first I need to check out my electrics

Also one of my XJS's takes longer to build up Brake Pump Pressure than the other one does, as one takes 30 Seconds and the other one takes 60 Seconds

Could it be that 'The Black Ball' Accumulator is a bit down on Pressure and needs replacing?

Thanks again for all your help

Much Appreciated

 

Hi Sidescrollin

It's after the Fuse, so it probably powers the Relay that turns on the 12 Volts to the Pump

But as the Brake Pump has Seized Up, I can't see anyway that I can Test it, as the Brake Pump will keep Blowing Fuses

Thanks for your help

 

OB
To test the circuit, just wire up the feed to a test light, it does not need a pump to be there.

 

Hi Greg

There are two plugs that go onto the Brake Pump, one of them goes to the Pump and the other one goes to the Pressure Switch on the Pump

The Pump itself is definitely burnt out but all the same it might be worth a try

 

Sorry, you misunderstood my question. You implied the circuit is not getting a full 12v. You indicated that it had 0.36v at the plug. I was asking you to check voltage at the other connectors in the circuit to find out where it is dropping 12v. The fuse was just an example of one of those connections because its often easy enough to pull a fuse and see if it has 12v coming to it.

 

Hi Sidescrollin

I've got the Car all covered up at the moment, as we had a bit of a Storm but I'll check the Voltage at the Fuse as soon as I can

 

Noise and electrical fields from you.

 

That will certainly cause a 32a fuse to blow.

Dismantle the motor and check the bearings turn freely and windings are not fried. If the windings are bad you can have the motor rewound.

I would think this will be a brushed DC motor so also check the brushes and commutator are not worn. If the Comm is badly worn and a brush is damaged it is possible for the brush to jam the comm and stop the motor from turning.

 

Hi Warrjon

Cheers!

The Motor is completely seized and way out of my comfort zone to try and repair it, as well as almost impossible to get the Casing off to look inside

So in my own case anyway, I think it would be better to try and find another one that works

 

Just to clarify, I meant plug in only the blue plug to the pressure switch, not the one that powers the pump. You should then see 12v at the plug that feeds power to the pump, just to confirm that the car electrics are working ok.

When it comes to replacing the unit, I would make the assumption that the pressure switch is faulty and contributed to the motor burning out. I assume you'll be looking to replace the whole unit anyway.

 

Hi Bladerunner

Yeah! I had a feeling that's what you meant, so I'll just plug in the Blue Plug into the Pressure Switch and hopefully get 12 Volts out of the Plug that 'Would' normally go on the Brake Pump

But She's all Covered up at the moment as up until today its been like November, so I'll probably have a go at it over the Bank Holiday

And Yes! I'll replace the whole unit, if I can find one

Thanks again for your help

 

Tell me about it! What a strange week of sun and terrible weather - I commute into London by motorbike so I'm very tuned into the weather! Where in the UK are you?

 

Take it to an auto electrician and have them evaluate it. I have not ever had mine out so I don't how it comes apart (but it will).

Do not try and run a seized motor or you will let the smoke out and it will never work again.

 

Hi Warrjon

Its got Steel Rings that are hammered flat into the side of the Casing, so while I could probably get it apart if I had to, it won't be a 'Walk in the Park' for me like it probably would be for you

And I very much doubt if they'd be any Change out of £100 to fix it, although I'm going to keep that as a 'Fall back option'

But there is a place not far me that dismantles Range Rovers where apart from a Slightly different Plug they look exactly the same and over the phone they were talking around £70 including the Ball

Which sounds OK to me, so after the Bank Holiday and when I know I've got 12 Volts at the Plug, after the Pressure Switch has been Plugged in, then I will pop over and see what they have got

Thanks for your help as always, I really appreciate that

ALex

 

Hi Bladerunner

One week out of April gone and we haven't even been out for a Trip yet

Thanks for all your help and one way or another, I'll get 'The Ice Princess' back on the road.