XJ40 silly question ?

"Jon_D" skrev i meddelandet news:HtQee.16389$ snipped-for-privacy@newsfe4-gui.ntli.net...

On mine -XJ40 -94 it shows ABS when there is a problem. You should see this two signs when you turn on the ignition key. The use to go off after a short while (20-30 sec)

The one you describe is brake failure ! It could be one of the sensor cables or worn out brake pads. It could also be that the brake pressure is to low. Have you flushed the brakes from air?

Pepe

Thanks for your reply Pepe.......

The brake warning (low pressure) does go away when the engine is started as expected so nothing wrong with pressure... but i do not get any ABS warning display when i turn ignition on before starting the engine.

your XJ40 94 has different pressure system (Teaves)

jon

Pepe, Your 1994 XJ40 is a totally different animal than the 1987-1989 XJ40. It has different brakes, different ABS, different engine, different electronics. They just look a lot alike!!!

The '89 XJ40 has 4 different warnings for the brake system. All 4 are those HUGE obnoxious warnings that come up on the right side in the display. They all have the Exclamation point with the circle around it. They are as follows:

"Anti Lock Failure" This means that most likely one of the sensors has gone out. The sensors for these cars, located in the top of each wheel hub need to be removed and cleaned on a yearly basis. They are stainless steel in an aluminum housing and in conjunction with salt and other road crud, they will eventually lock in place and form weird electrical signals. Taking them out, cleaning them and using a light grease when they are re-installed will avoid all that. The ABS computer will also throw this warning as will other areas, but if you are not getting the warning -- don't worry about it. It is a complicated system.

"Low Brake Pressure" This means that the "Green Blood" commonly known as HSMO (Castrol Mineral Oil) that is in the Green reservoir is low or the accumulator is gone or the pump is shot. 9 times out of 10 it is the accumulator. Unlike the 1990 Teves system which has an electric pump, the pump on the '87-'89 XJ40 is engine driven and mounted on the front of the engine. The pump RARELY goes out. It is normal for this warning to appear when you first start until the pressure builds. It should then go away. Keep in mind that if you are restoring this car back to original than the HSMO also runs the Self Leveling rear shocks and they go out ALL the time thus sending up this warning continuously.

"Brake Pad Low" This is self explanatory -- for the most part. Again, unlike the 1990+ XJ40, the '87-'89 has a pad sensor on all 4 wheels, not just one in the front and one on the rear. The wires on these pads are fragile and it is common for new pads to show the warning within days of installation. If this happens, the choice is to buy new pads because you can not remove and replace the sensor or you simply wire the sensor wires for the offending sensor together thus completing the circuit and make the warning go away.

"Brake Fluid Low" This is the most serious of the warnings. This means you have a problem with the hydraulics (brake lines) on the car. You need to determine exactly why this warning is appearing sooner rather than later.

While on the subject of fluids, keep in mind that the '89 XJ40 uses Automatic Transmission fluid (ATF) for the power steering -- not Power Steering fluid like most cars and not HSMO like some of the later XJ40s. Check to see if the reservoir is full of red fluid or not. In my case, since I have teenagers that drive my XJ40, I converted to clear power steering fluid since cap states "Power Steering" and I KNOW that is what one of my teenagers will put in there!!!

The Haynes manual has some good points, but I suggest that if you are serious about doing a re-build on this car that you get the JDHT CD for about $23 USD.

It is basicallythe original service manuals scanned and placed on a CD. Also get a copy of the original Owner's manual which explains all the things on the dash that the manuals do not.

Webserve

Thank you for your reply... Lots of very usefull points....

The UK MOT requires that the ABS warning shows when ignition is turned on but engine not running so I have to get to the bottom of the problem. I have performed some fault finding today and found that removing the 'Overvoltage relay' (taller white case located under the fuel filler pipe) causes the 'Anti Lock Failue' warning to appear. I replaced the relay without its cover to check operation and found that the relay actuates when the igintion is turned to 'On' position. I beleive this should not actuate until the engine starts. As you correctly point out, the Haynes is not very useful in some areas as the wiring diagrams are not complete, and are of no no use in this case. I will need to obtain a wiring diagram that includes this circuit to close this problem I think. The braking systems are working normally in all other respects including ABS.