Well...seems the dash continues to show a "Brake Assist Failure" statement, with amber lamp illuminated, on the 2006 S-type (3.0) base. No codes are being generated, nor are there any stored, or other permanent codes relating to this (or any other system notification). I ran my cheapy Craftsman OBD, and my OBDII MX+. Both show all being well in the Jaguar jungle. I cleared and tested several times throughout the driving day. I believe I made three separate 3-5 mile trips today, each time checking, clearing and checking per the instructions (ign on/eng off, etc.).

The brakes feel very good underfoot, with the car stopping well within expectation, equally and positively.
I am not a brake professional, though believe this system is mechanically correct. I should mention that I'm also able to hold the pedal firmly without loss of pressure (does not fade slowly to the floor), nor is the any apparent fluid leakage (floor, wheels, reservoir).

Thoughts of any kind?
Thank you!

 

06+ V6s have a vacuum sensor on the brake booster that the V8s don't need, it ramps up line pressure in low vacuum. 99% chance it's gonna need a booster, you might be able to take the sensor out and swap them from the used to the new but be ready to do the full job.

either way get a better scan tool that can read the DSC module next time. thinkdiag mini is cheap will read all modules

 

There will be codes but you're using tools which only read emissions stuff. Can't blame them for not reading anything else.

 

Ordered the Thinkdiag2..Greatly Appreciated, X.

 

Right. So so glad I had not.
Thinkdiag now on order for early delivery. Let's see what the new unit has to say, shall we?
Crossed fingers it won't add to the Bromwich Sandwich.
Cheers, Kevin

 

Wiring diagrams here:

JagRepair.com - Jaguar Repair Information Resource

See figure 05.1. I think this sensor is called the "DSC Vac Sensor" in the wiring diagram, shown near the bottom of the page. Note how this sensor has two channels. Not sure of the logic that turns on the warning message, whether one or both channels out of range, but it wouldn't hurt to compare the channels.

In the workshop manual (same link as above), see page 446 of the PDF. The diagram shows the sensor as item #5, now called the "brake vacuum sensor":




At the very minimum, make sure the connector is clean and secure.

 

Thank you, Karl. I'll have a look, removing the connector/cleaning with contact cleaner and replacing..then crossing fingers and all else. Wonderful to have this now saved resource. Thank you very much.

I had to look up Sandy.. I'm from Olympia, but haven't lived there since I was a kid.

Cheers, and thanks!
Kevin

 

In your sig, I see you have a 1948 ******. Here's mine, a 1948 CJ-2A in the sand at Long Beach, WA:


Flathead L134, 6V, mostly stock...

 

I thought they had banned driving on the bench now?
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