On my 99 XK8 daily driver, I previously had all the usual dash warnings caused by a low battery so R&R-ed the alternator. That cleared most things and now don’t need to use a battery tender. Strong 12.8V at morning start up.

However one intermittent “Low Brake Fluid” remained.



So onto the diag. Brake fluid level checked and was full. Cleaned connectors on both the brake fluid reservoir and the ABS module. Checked pins and had wire continuity on both the tank sensor and to pins 1 and 13 of the ABS module connector.

Drove it and intermittent warning remained. Put a paper clip on the tank sensor connection, drove again - warning remained intermittent. Tank sensor not the fault then. Very rare to see this type of failure anyway.

Carried on driving until I had the warning in a car park, and right there pulled out Meter and checked continuity for the wires. Good! Hmmmm...

Now onto 2 other scenarios - 1. PCB soldered Pins inside ABS module have gone bad or 2. Swinging ground. As I’m a “cheap skate” I always shoot for the low hanging fruit (ie easy) things first. So I went for 2. first.




The ABS module ground is off pins 8 and 24 and the car ground stud LF3 is under the brake reservoir on the front wall of the compartment. Really PITA to reach.



Checked other adjacent ground stud to the eyelet connection (not the stud) to this LF3 ground and noted a 0.5V drop whereas should be zero difference.

Started unscrewing and noticed corrosion on the mating surface and nut.



Cleaned LF3’s all mating surfaces up to bright and shiney and Warning Message hasn’t appeared for a couple of days.

Let’s see if this holds good.

 

Wow, a hell of an investigation David- NICE JOB!

 

What Johnken said!

 

Well done....

 

Terrific! I have this same issue on my new arrival. You mentioned the ground is PITA - what angle did you use to get to it? Would it be easier from underneath?

 

Rojeho,

You have to work from above as it’s a closed compartment in the engine bay. Fiddly to work under the brake fluid reservoir but doable with socket and short extension, wrenching under the connector and pipework.

Getting grit paper to clean the connection was a “ bit on a string” job plus grit paper taped to a screw driver. I also use silver paste on these sorts of connections as I find it helps prevent the problem returning ... in the long term.

Check continuity/voltage/resistance from the wire connector’s eyelet (not the ground stud) to another body ground to see if there is a problem.

Good luck otherwise you’re onto scenario 1 which means ripping into the ABS module internals.

 

Thanks, David. Definitely worth the effort here "hoping" for an easy fix.

 

I get an occasional DSC FAULT light on my 2003 so I looked for the ABS ground to try. On 2003, it is on bracket next to the ABS plug where it connects to the ABS pump. Loosened ,cleaned, re-tightened connection. Hope this corrects the DSC problem. It disappears if I turn ignition off and re start. Seems to be unrelated to switch. ABS sensors, reluctor wheels (4) F&R cleaned. Battery 12.6V. Will confirm if this eliminates the problem.