When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The brake switch fitted to cars equipped with cruise control have two switches in the mechanism.
With no pressure on the brake pedal one switch is normally open circuit and one is normally closed circuit.
The normally open switch closes when the brake pedal is depressed to activate the brake lights and the Park gear selection interlock etc.
The normally closed switch opens when the brake pedal is depressed to disconnect the cruise control.
I was having trouble with the normally open switch in that the brake lights were INOP and the Park interlock would not release.
The cost of a new switch from Jaguar is bizarre to say the least so I removed the switch from the car and went to the local electronics supply outlet to check out their micro switches to see whether there were any that I could use.
As luck would have it there were some available which were exactly the correct size and would fit into the housing. They had three contacts, a common, a normally open and a normally closed so all I had to do was connect the correct micro switch to the correct wires and my problem would be solved.
It was pretty straight forward to test the original micros with a meter and determine which was open and which was closed and replace them with my new switches wired up to perform the correct function.
All this took about half an hour and it tests correctly so I will re-install it in the car tomorrow.
The reason the original switch has little machine screws holding the micros in place is that I took it apart a few years ago to try and clean out the micros, there were originally rivets there which I had drilled out.
Thank you for taking the time to research this. A switch that occasionally does not activate the brake lights could have deadly results. I have read about problems with this switch as it ages.
One thing to consider is the throw of the switch before it makes or how much of a dimension must the button be depressed . The micro switches come in different specifications and if you put a new one it you might find it doesn't make . Ran across this as I had the wiper park switch inside the gearbox .
03-13-2018, 04:24 AM
X300 Brake Switch.
