Hello I have a 2003 xj8. All 3 brake lights are not working. I checked the bulbs, and fuses in the engine compartment and trunk. I replaced a 25amp fuse in slot 5 in the trunk. All blinkers, reverse, and fog lights work. I looked up some old threads and saw something about a sclm. There are no messages in the message center on the dash........Any suggestions or advice on how to fix this? Thanks!

 

The stop, reversing and rear fog lamps are controlled by the security and locking module (SLM) which receives inputs via the SCP network from the BPM.

Before assuming the worst and going for a module failure, I'd eliminate the Brake Pedal Switch:



Graham

 

have you checked your bulbs in the high mount stop light? The 3rd brake light doesn't get monitored by the SCLM. It shoudl work even if your module is gone.

 

yeah the third brake light bulbs are good, but they dont light up when i step on the pedal.. how can i check the switch, with a volt meter or some other way? thanks for the diagram too GGG

 

One way to test the switch is to remove the connector and us a ohmmeter or continuity tester to measure across the contacts. It should change condition as you press the pedal or operate the switch. You can also test the switched lead for power to ground with a test lamp.

 

when you have switch out to clean, check that the plastic arm that contacts the pedal has not got a slight groove in it. mine did and brake lights stayed on unless i tapped the pedal sideways. filled with a bit of plastic metal and now ok.

 

Hi
Here are 2 forum threads on rear brake lights not working:

The first one only has 7 posts in it (gives good summary info and leads you to posts numbers in the second one).

https://www.jaguarforums.com/forum/x...problem-58284/

In the second one -look at the earliest posts (post numbers 1 thru 7)

https://www.jaguarforums.com/forum/x...b-10830/page4/

Forum member does circuit board repairs that might save buying another module.

Jim Lombardi

 

Just to add to what sparkenzap said, I'd mention that switch may exhibit partial failure where it shows a higher than normal resistance when the contacts are closed.

This is the case on the brake light switch assembly that I removed from a '99 XJR this week. It was reading anywhere from 30 to 50 ohms when it was supposed to be closed. Should have read just a fraction of one ohm. This apparently confused the controller modules -- in my case, it made the Parking lock solenoid release quite erratic. Popped in a new switch and all was well.

BTW, the brake switch is hooked to the two outboard pins of the brake light assembly connector, and is normally closed. It should normally read close to zero ohms, and then change to infinite ohms when the brake pedal is pushed.

(The inner two pins go a a normally open switch that is part of the brake cancel circuit for cruise control.)

 

Hi
I found this TSB 206-07 on Brake Pedal Switch that motorcarman posted in "Yet Another Failsafe Engine Victim: thread.

Here is the weblink to view this TSB (go down to Page 4 for XJ models - Pages 1 thru 3 are for XK models):

https://www.jaguarforums.com/forum/at...-206-07am3-pdf

Jim Lombardi