Hi All,

My XJR has the fault where the ABS and TRAC lights come on above 20km/h, which is pretty much always the two ABS pump pins on the module circuit board having cracked their joints.

Now, I've just pulled the ABS unit out, cut the module open and re-soldered these pins and glued it all back together.

Today I've put the unit back in the car and I'm now getting an immediate ABS fault the moment the key's turned on, so not the same fault as before, something different..Now I've yet to bleed the brakes so the ABS unit is empty of fluid, is that a possible cause?

I've pulled the unit out and put it back in a couple of times to check all the pins on the connector aren't bent and are fully pressed home, but the symptom persists. I guess the other options are that:

a) In pulling it out I've flexed a wire that's broken or something, but I was pretty gentle and careful in doing so.
b) I've somehow damaged the circuit board in the process, but I was pretty careful in handling it all and only really touched those two pins, didn't go near the rest of the board.

I know that an immediate ABS fault's usually something like a wheel speed sensor disconnected or not connecting properly. The connector and pins look in great condition and it's seated fully in. I've also made sure the pins have all been cleaned with contact cleaner.

Should I press on and bleed the brakes and see if that improves things? I've got a couple of ELM327 OBD readers here but neither of them play nice with the X300 and don't connect or give me any clues, so I don't have that route open to diagnose any further, I guess sourcing something that can talk to it would be the next step to see if I can figure out what's making it unhappy. Failing that, I'll try to find a new ABS unit.

Thanks,

George.

 

The fault code and lights will not disappear until car driven to 12,5 miles / hour

It will not reappear until 3 faults

Remember to put a U in the bleed hose and the procedure is in the Jaguar manual , see post # 4

http://www.jaguarforums.com/forum/xj...manual-253724/

The wheel speed sensors can be removed and the face or the sensor cleaned but are easily stuck in the hole and can be broken ( plastic pops off ) , not a cheap sensor , there are 2 different sets of sensor part #s for the X300 depending on VIN

You can put a meter on the module connector and spin the tire in the correct direction and read about 1 volt AC as functioning

A basic meter reading is 1300 ohms resistance through the wire pairs noted by the colors in the pic

There is a brake switch involved on pin 20 , the brake switch is 2 switches in 1 package with 1 dedicated to the rear brake light

A ground ( through the brake switch pressed ) at 20 will disconnect the anti - skid

 

Thanks for the information. So you're saying that it may be normal operation for there to be a fault condition when you reinstall the ABS module that won't clear until it's driven? I did run the car up on the hoist but of course that's only the rear two wheels spinning, not all four, so it may not reset the fault condition if that's what it needs. It's just odd that the original fault it had reset after every re-start and only appeared once the car was rolling (symptomatic of the bad ABS pump pin contact). I would have thought that the ABS system would test as fine at key-on unless something was damaged, but if uninstalling and reinstalling (or unplugging and re-plugging in the connector) resets the unit somehow you may be right in that it needs to be rolling to re-test and reset the fault condition.

I doubt the wheel speed sensors are at fault as they seemed to work well before (my cruise control still worked and my understanding is that if a wheel speed sensor is out of range then the cruise control will not work), unless one of the connector pins is no longer making good contact after being disconnected and reconnected.

For anyone else who has done the pin solder repair on the ABS computer, or who has disconnected and re-connected the ABS controller, was it normal behaviour for your car to display an immediate key-on ABS fault after reconnecting until you drove it over 20km/h? If so I'm probably worrying over nothing.

 

The " dampened " fault light and reset is hard to keep track of so the ultimate test is on the road

2 or 4 wheel ? all I can say is from technical doc , never had a TC / ABS fault light , but I did confirm 1 volt AC on wheel in air spin , the 1 volt only shows in the correct wheel spin direction and a left sensor part # will not work on a right and vice versa , I broke one of my sensors prying out , Motorcarman has a trick to getting one out from his experience

Cruise control is only 1 sensor also used for speedo , left rear

 

Cool, I've read elsewhere that some ABS faults can be persistent until a 12.5MPH self-test. The motor current (pin solder) fault isn't like that but if maybe disconnecting and reconnecting my module caused a different fault case then that might be a persistent fault that needs the 12.5MPH condition to reset. I'll try bleeding the system and get it off the hoist and run it up to see if it clears. If the fault persists then I'll look at pulling it apart again and fault checking. There's little point looking for a fault that may not actually be there until I'm sure it's there

 

Too bad it can't be reset until on the road and plumbed and not just connector installing

One of the first things is to remove sensors and clean the faces and may have to revisit ( may not be related to 1695 code of solder joint electro - hydraulic EH valve as the module's final output and not the sensors sensing input side )

 

Just as a follow up to this. Once the brakes were all bled up I took the car out and as soon as it hit the 20km/h self-test speed the lights extinguished and I now have a fully functional ABS and TC system.

Worthwhile posting this up in case anyone has the same symptoms post doing the repair and are worried they goofed something up, get it bled and drive it and you might be pleasantly surprised!