I am the recent owner of a 2003 XJ8. A code has recently appeared that reads engine failsafe mode. I have noticed my brake lights are on and not turning off.

My question is should I purchase a new brake light switch?

thank you, Jeff S

Submitted by stevejag@sbcgl… on Sat, 05/10/2014 - 12:00

Edited on 2014-05-10 12:01:44
Phil- Jeff-
Here is an example of the brake pedal sw in your car. It is a compound switch containing two microswitches. Yes, it can cause the engine failsafe mode message, one or two other messages, and also cause a loss of cruise control.
As far as the brake lamps, your problem is likely the Security and Locking Module as you were told. The pedal switch only serves as a signal to that module, and it controls the brake lights. So if one is staying on the module is probably the culprit.

David-
We need to be careful that we are sure we know which model and model year vehicle we are talking about. The adjustment you mentioned holds true for your XJ40's; but in 1993 the pedal switch was changed to this design. I believe it started out with a metal housing, but has since changed to this plastic one. So, Jeff, Phil, and you with your XJR would adjust the switch, if necessary, by adjusting the ratcheting mechanism on the white lever in this switch. The housing itself has no adjustment.

Hope that helps!

Submitted by deltajhotel@aol.com on Wed, 05/07/2014 - 10:38

All else being equal, the brake light switch activates the brake lights when the brake pedal is depressed and released. Slotted holes in the switch plate allow for adjustment for brake lights on or off. Not sure about the security module, but would check the brake light switch first.

Submitted by pvtilly@yahoo.com on Wed, 05/07/2014 - 08:16

I'm told by local dealer service mgr that my problem is with the security module. Seems it is sending power to the passenger side brake light constantly. Needs to be replaced. Dealer does not have module and cannot get it. I have looked several places and cannot find. Any thoughts?

Submitted by deltajhotel@aol.com on Tue, 05/06/2014 - 19:53

Hi Jeff

This could very well be a problem with the brake switch causing the failsafe mode especially as your brake lights stay on. There are other reasons, however, I would check the brake switch out first.
Best of luck