Consulting Jaguar Classic Parts, the two part numbers for the X300 brake light switch on an automatic with cruise(speed) control are:

LNA6420BA (old)
LNB6420BA

Brake Pedal Housing-Automatic - Parts For XJ Series from (V)720125 to (V)812255 (X300) | Jaguar Heritage Parts UK


However, neither appear to be available any longer. But many sites like Rock Auto and Jagspares list the LNB6420BB as the part for the 1995-2003 XJ that supercedes LNB6420BA. But Jaguar Classic Parts, which I usually consider the master reference, does not.

Even aftermarket seems to indicate the BB supercedes the BA.

http://www.wellsve.com/custom_search...ngs/SW9225.pdf



Can anyone confirm that the LNB6420BB is now the correct part number for the X300 brake light switch?

.

 

Al,

I find that jaguarclassicparts.com is not always complete in its supersession records, so I double check with one of the Jaguar dealers who sell parts online, such as jaguarmerriamparts.com or gaudinjaguarparts.com. Checking with Jaguar Merriam shows that BB is the correct supersession for BA.

According to the Jaguar Electronic Parts Catalog (EPC), which you can download for free from this forum, LNB6420BA was the correct part number for cars with Cruise Control, LNB6420AA was the part for cars without Cruise, but according to Jaguar Merriam, both parts supersede to LNB6420BB.

Cheers,

Don

 

I can't remember the part numbers but years ago my attempts at getting the original switch were fruitless. I ended up with the X308/XJ8 switch.....which everyone said was the official substitution.

The wiring for the newer switch is slightly different. In a moment of weakness I opted for the adapter harness for about $50. It was a silly purchase as a few minutes of cutting and soldering to swap connectors woulda done the trick

Replacing the switch, which at first blush you'd think would be a 10 minute deal, was surprisingly 'fiddly' ....grrrrrr.....but that has nothing to do with the design difference of the X308 switch. It's just an awkward job


Cheers
DD

 

BTW, I have confirmed that in my 1997 XJR I still have the older style metal housing brake switch with the attached ~6inch long wiring harness.

As mentioned above, the new all plastic XJ8 style switch LNB6420BB that supersedes the older metal units does not have this harness.

So if one has the older style, the choice is either to construct an adapter lead or buy the Jaguar part LNB3022AA adapter harness.

The adapter LNB3022AA harness is not readily cited, so I thought I'd post it here for easy reference.

.

 

Very timely, I'm getting tired of stomping on the brake pedal to make the 3rd brake light go out every time I get in the car:-)

 

Yep, same here... I just noticed that my brake lights are no longer triggering fairly frequently. I didn't realize they weren't, which is really dangerous of course in stop-and-go traffic like I encounter in my commute.

So the car is "down" while I await the parts.

It will be curious to see how the new plastic part bolts in, as I don't want to crack it.

.

 

OK,

Got it changed out today for the new switch and harness. Working fine now.

Some quick tips/info before I forget.

This job is a bit of a pain since you have to get up under the dash above the brake pedal, and will likely be lying on your back or twisted in some weird position. If you can't work in that position, you may want to take this to a shop.






Here is what the old style X300 metal brake light switch look like, which is superseded by the X308 plastic switch:





Here is what the new style X308 plastic brake light switch looks like:









But with the info below it really isn't a hard job. If you have everything you need ahead of time, I'd estimate an hour of time at the worst. You'll probably spend more time dressing the wiring harness following the install than removing/installing the switch itself.

Parts:

LNB6420BB New model XJ8 style plastic (versus X300 metal) brake switch, doesn't include wiring harness, cost is about $100
LNB3022AA New model switch extension harness, cost is about $40 if you look around





Tools:

Medium phillips head screw driver (to remove driver knee bolster)

10mm socket (to remove AC/heater vent panel under bolster)

7mm deep socket, 1/4 inch drive (for switch lower bolt)
or
7mm socket with 1/4 inch drive 2-3 inch extension, longer extension will not work

8mm open/closed end wrench (for switch lower nut)

1 or 2 small zip cable ties


If you remove the lower driver's bolster (4 phillips screws) and the AC/heater duct up under the bolster via removing one nut, your access to the switch is much improved. You'll definitely save a lot of time by removing these two pieces in my opinion.

The switch is held on with two bolts, one at the top and one at the bottom of the switch. But the top bolt is a slip fit so doesn't need to be removed. This is very good news as it would take some serious contortions to get up there to remove and reinstall that top bolt.

The bottom bolt is a 7mm hex head bolt, and its nut is an 8mm nylon lock nut. You'll need a very short (2-3 inch) extension or deep socket to get to the head of the 7mm bolt due to the location of the brake pedal arm. The 8mm lock nut needs a small wrench as a socket will not fit inside the brake pedal assembly.

Once you remove the 7mm/8mm bolt and nut combination at the bottom of the switch, the switch just slides down and off the top bolt. Disconnect the wiring harness and discard the old switch.

Re-installation is the reverse. Just slip the new switch upper tang under the top bolt, then rotate the switch such that the bottom hole lines up with its mounting. Then install and tighten the 7mm/8mm bolt and nut. I don't know if there is any torque value, but you'd never get a torque wrench in there anyway. So I just tightened the bolt so that its end was flush with the nylon lock nut, which is how it was before removal. At that degree of tightening I didn't see any noticeable stress or disfiguring of the plastic switch where the bolt was tightened.

Then just plug in the extension wiring harness into the switch and vehicle harness where the old switch was connected, and find a route where the wiring won't get damaged or interfere with the brake pedal. I zip tied it to the steering column.

....that's it. All done.



Now here's some humor to wrap this up. So after installing the new switch/harness, I pressed the brake pedal to test the brake lights... and looking in my rear view mirror I see the high-mount brake light sag and fall off the rear window! Nice coincidence.

At least the brake lights now work *sigh*


.... just add one more minor repair to the list!




Hope that is helpful info for anyone replacing this part.

.

 

You can also buy the X100 brake switch and discard the metal bracket. The X100 has an extended link harness and I usually just buy the cheaper X308 switch and install on the metal bracket.. The wires can be removed (unsoldered/desoldered) from the small circuit board and transferred to the new switch.

I would guess you could do the same thing for the X300.

Several ways to 'skin-the-cat'.

bob gauff

 

I'm getting ready to buy a switch and just for laughs I've found a few of the old obsolete metal ones that are new for between $40-50. They say Burgess on the outside and you don't need the connector. Given that the original lasted 18 years, whats the downside?

Jaguar Brake Pedal Switch Xj6, Vdp, Xj12 95-97. LNA6420BA, DBC10800 - Jaguar Parts Specialist

 

Cheaper than Rock Auto.
You must be looking in the right places!!!!!!!!!!!!!!!!!

bob gauff

 

Al thank you so much for the instructions, I printed them out and it took me 45 minutes which included gluing this piece back together, picture below, that sits next to your left foot and cleaning the lower drivers bolster and finding some more screws because it was only held on by one screw. Now I have working brake lights ;-)

 

Thanks so much for your post!!! It was definitely back breaking, but I did it. In fact the brake light switch only needed lubricating.