Hi Guys,

My XJS failed its mot on the abs light. Symptom: ABS light goes out as you move away as normal, but each time the brake is applied with medium pressure the abs light comes on, as soon as you take your foot off the brake it goes out. I've worked out how to test the abs ecu by shorting out the attached connector and have a fault code 21. Which is described at a Main Valve problem. I've since checked the solenoid valves by shorting pin 7 common and then each solenoid in turn and pin 5 sounds a bit dull in comparison to the others.

Before I go diving in, have i diagnosed correctly will a strip down of the actuator unit and solenoids fix my abs issue?

Thanks Gary

 

Hi Gary

First of all does the ABS Light go off when you first Start the Car before you touch any Pedals?

In any event the First thing to Check is the Fuse which could be Blown or Dirty or Not Making very good Contact

Or Going Weak Under Load

Check Both Fuses: The Brake Pump Fuse and The ABS Fuse (See Photo)

If you suddenly Jab the Brakes, does the Car suddenly try to pull to the Left or the Right?

Then Report back with any Unusual Braking Symptoms

It could be a Brake Pump problem, although it sounds more likely (from what you have said)

That there 'could' be a problem with the ABS Valve Block

If so Don't go stripping it down (just yet) as it could be an easy and inexpensive fix (in the Scheme of Things)



The ABS and Brake Pump Fuses are located underneath this Panel (level with your knees)



The Brake Pump and ABS Fuses are Clearly Marked on the inside of the Lid of the Panel
Check them both