Hi All I have a 1993 XJ40 Van Den Plas, this morning the shifter stuck in park and the brake lights dont work, when i press the mechanical shifter lock release button next to the shifter the shifter lock releases. I am presuming i should start with the brake light switch, can anyone help me locate it and tell me how to remove and test it. Is this a difficult task? Many Thanks and all the very best of wishes for 2021

 

Hi Kev,
For the sake of clarity, Did these problems start at the same time? My first thought is that you have 2 unrelated problems. I dont think that a faulty brake light switch would cause your car to not start. Also, my 94 has a lockout "feature" so that it wont go into gear unless there is a foot on the brake. Mine is broken. As far as the brake lights, I would start by checking the bulbs. However if they are no good, there should be a light on your dash saying so. Good luck...

 

Hi Jerry Thanks for your response, I may not have been very clear, the engine stats and runs, just the shifter locked in Park and the stop lights not working.
Cheers

 

Hi Kev,

I think you are on the right track. The brake light switch controls the brake lamps and also the gearshift interlock solenoid, by way of the Central Microprocessor (CPU). Here's the schematic for the gearshift interlock solenoid circuit:



The brake lamp switch is located at the top of the brake pedal lever, Part 12 in this diagram:

The part number for cars with cruise control is LNA6420BA and unfortunately it is no longer available from Jaguar, but it would be worth checking with David at everydayxj.com and Kevan at growlerparts.com to see if they may have a New Old Stock switch. The earlier part number DBC10800 should also work. Alternately, you may be able to repair your existing switch or find a good working salvaged one.

One other possible cause of your issues is corrosion on the electrical connectors and/or circuit board of the CPU, which is a known issue caused by condensation from the A/C evaporator pooling on top of the climate control unit due to clogged drains, then spilling over onto the CPU while cornering.

Cheers,

Don

 

Hi Don
This is excellent, many thanks, I am now confident to proceed and see if i can remove the switch and test/repair. Question if I may, is there two separate switches, one for the brake lights and one for the Park or does the same switch operate both.
Many thanks again for your help

 

On later models, the brake switch has two circuits with two different switches in the same case, but if I recall correctly the XJ40 switch has only one circuit and one switch that operates both the brake lamps and actuates the gearshift interlock solenoid to unlock the gearshift lever from the Park position. Part 12 in the diagram is probably the cause of both problems on your car.

 

Hi Don
Went out to start the removal of my brake light switch but before doing so started the engine, then pressed the brake and heard the release solonoid working, the shift lever worked fine and the brake lights worked. Looks like it fixed itself. So looks like this is an intermitant fault. Would have thought that if the brake light switch was at fault it wouldnt have "fixed" itself. Should i just be thankful and move on or try to source the fault? What is your advice?

 

Intermittent failure of the brake switch is not uncommon. Chances are good that the fault will recur. The switch is the common point between the brake light circuit and the gearshift interlock circuit, so it is your prime suspect. It is possible that the electrical connector has vibrated loose or the contacts are contaminated or corroded. You could try flushing the terminals in both halves of the connector with zero-residue electronic contact cleaner (CRC brand is available at most auto parts stores). Allow to dry and then securely reconnect.

If the problem recurs, it would be worth removing the switch to see if you can take it apart and clean the contacts and perhaps reshape them if necessary. I can't recall if the switch housing is connected with screws or rivets. If rivets, you may need to drill them out for access to the switch internals. Be very careful when disassembling the switch since there will be small parts inside that may scatter everywhere, and try to note how they are arranged inside the switch case.

 

I had a similar issue with a '94 XJ6 I just purchased. The car has sat for about ten years and the seller said it was "stuck" in park. I tried the manual release method (small access hole next to the shift lever) but I couldn't get that to work. Maybe I didn't push down hard enough or the screwdriver wasn't hitting the right spot...anyway, it didn't work. Then thanks to the tips in this forum, I checked for brake light. No brake lights. I removed the brake light switch from under the dash. This is NOT easy. It is only one nut and bolt but it is very difficult to get both hands under at the same time. Also, the nut is 8mm and the bolt head is 7mm?? Why?

On mine, there are two separate micro switches (one for brake light circuit and one for the cruise control). They are branded Burgess and have the number 9336 printed on the side. So far, I have not been able to find an exact replacement.
I jumpered the the White/Orange and Purple/Blue wires, inserted the key and turned it to position 2 and the shift lever came out of park easily.

The help from this forum was invaluable. Thank you all.

Two Burgess micro-switches removed by drilling out the rivets.

 

Jaguar has used micro switches similar to those in various places. Most recently I replaced one governing the park function inside the wiper motor. My XJS has at least 2 so far. They are not expensive, and golf carts use them on their gearshift knobs.