Damnation....now my car has the ABS and Brake light on..WTF Drove home with nearly no brakes.

 

Hi Malc

Is there any Brake Fluid in the Reservoir

Can you hear the Brake Pump Running

Do you have to push the Brake Pedal really hard to Stop her

Does the Brake Pedal go straight down to the floor

Have you checked the Fuses

 

Thanks OB
1 yes full
2 I will listen
3 yes
4 nope
5 yes 2 30 amp

Cheers

 

Hi Malc,


There is a way to get the ABS control module to flash an error code. You have to link together a couple of wires in the trunk, turn on the ignition and the dash ABS light will flash numbered codes. Might give you a start.


The whole procedure is described in the official Jag manual. Do you have access to one?


Cheers,


LeeP

 

I will check that out and see what I have downloaded over the years. Thanks

 

This is for a pre-facelift but might help to get you started. I think the shape of the thingy you have to bypass in the trunk may be different on facelift models.


Cheers,


LeeP

 

Hi Malc

If you have to push the Brake Pedal Hard to Stop Her, it could be the 'Black Ball Thingy' aka the Accumulator.

May need re pressurizing or renewing.

 

Today l unplugged and cleaned the plugs and connectors on the unit and pump. The pump isn't pumping but it does have 14 v going to it. Is it neg controlled ?

 

Yes there is a plug in the left rear trunk (boot) wheel well and l did the shorting test. It came back with code 21. This is a front or rear left or right in or outlet valve failure. what ever they are......

 

This is shown as a main valve failure or front or rear left or right in or outlet valve failure. What ever they are......? Any idea where to look now and how bad is it ?

 

malc4d,

That's relating to the valves in the ABS valve block. I'd be tempted to try a full flush through and bleed especially of the front brakes a few times and see if it can resolve the problem before you start thinking about stripping or replacing the valve block.

Good luck

Paul

 

Thanks Paul. It also says could be a cable short problem. Is this more likely ?

 

Hi Malc,


The valve block is where the hydraulics and electrical systems come together so that if a wheel locks up the electrical system detects this and reduces the hydraulic pressure to that wheel. It all happens in an instant with the brake being rapidly applied / released until it stops locking up or the car comes to a stop.


There are inlet and outlet valves for all 4 wheels operated by electrical solenoids in the valve block plus a couple more for front and back. A complex bit of kit and that is about the limit of my knowledge but Orangeblossom knows them inside out.


You can perform a series of electrical checks by measuring voltage / resistance at the big connector that plugs into the ABS ECM in the trunk. This includes fooling the system that a wheel is locked up by bridging some of the terminals and checking if the wheel will rotate with the brakes are applied (car jacked up). There are also variations to check if there is a cable problem or a problem in the valve block itself.


You will need a good multi meter to do the above and the tests (32 in all but only 11 relate to the valve block) are detailed in the jag manual. It sounds complicated when you read it but take your time and work methodically and you will be able to get a better fix on just where your problem is in the system.


Good luck,


LeeP

 

Today after letting the car sit in the naughty corner for a week, l tried some unplugging and checking of relays. It seems the pump relay isn't making contact between the pump 12v feed. After jumping the contacts the pump pumped up the system and l got rid of the brake warning light and had brakes....yippee. new relay ordered. Still have the ABS light though. dam !!

 

malc4d,

Good to hear it's getting sorted. Don't worry about the light until you've driven the car. I've seen plenty of XJS that had problems and light illuminated, but would extinguish when problem sorted and then driven past about 10mph.

Paul

 

Today fitted the replacement relay and the brakes worked...but that dam ABS light is still on....grrrrr. Guess that means no ABS brakes at the moment.