Hi,

Appreciate your guidance and advice and apologise if asked previously

Rear boot spoiler brake light not working, suggestions to carry out diagnostics please - Thank You . . .

XK Convertible

 

Check fuses; check connections...

If not something obvious, check wiring loom for damage and trace circuit using wiring schematic.

 

Thank you NBCat,

Appreciate your prompt response,
sorry to ask maybe the obvious,

would you know the location of the fuse and fuse number ?

Thank you again . . .

 

Fuse references can be found in the vehicle Owner's Manual and in the Workshop Manual.

There are several electrical junction boxes in the vehicle: the power distribution box in the LH side of the engine compartment; auxiliary boxes behind the centre rear arm rest; in the LH footwell and in the compartment housing the battery.

The fuse for the high-mounted stop lamp is located in the auxiliary box behind the centre arm rest.

 

Hi BJ, do the other brake lights work? If not, check the fuse first. If only the CHMSL is not working, open the lid and remove the lid liner. There are two 10 mm cap screws near the bottom. Once these are out, gently pop out the eight red trim pins that continue to hold it in place. Find the wire harness going to the CHMSL and disconnect it. Using a separate power source, a nine volt battery will do, apply power to the CHMSL to see if it will light (some one will have to operate the brake pedal for you). If it lights, then begin working through the harness that provides power to it looking for a broken wire or damaged connector.

 

Hi Jack,

Thank you for your response

YES the standard Brake Lights function ok

If I understand correctly,
Open the boot and remove the boot liner
with the 10mm cap screws and trim clips

Sorry, could you confirm what "CHMSL" stands for ? and where it is located ? - is this a control relay to power the LED light ?

- is this the actual LED spoiler light unit ? - or a control unit mounted under the boot liner ?

Don't understand why somebody needs to press the brake pedal if applying a voltage direct, unless the CHMSL is a relay and placing a separate power source will test the output of the CHMSL - which in turn should power the LED light ?

Thanks again . . .

 

CHMSL - Center High Mounted Stop Lamp

 

Sorry for the confusion, the LED lights in the spoiler is the Center High Mounted Stop Lamp. You won't need the brake pedal for the first test so see if the light will light, only if you have to trace through the harness looking for a problem.

 

Thanks Jack,

Will carry out the tests and let you know the results

Many Thanks again, much appreciated . . .

 

I found that when one LED burns out - the whole unit quits functioning. Kind of like on an old fashioned Christmas tree light string.
I went here and got a new lamp:
HIGH MOUNT LAMPS for 2007 Jaguar XKR
20 minute install. Just make sure you have a tamper resistant star drive bit set.

 

Hi Tim,

Thank you for response, how did you manage to remove the plastic covers on the lens to access the screws, (without breaking them) - do they lift from one side,
or do you have to press them together - Ta

The tamper resistant start drive bit set - are they standard sizes ?

Thanks again . . .

 

There's a little notch to put the tip of a small screwdriver in. Gently pry until you can get a grip with your fingertips. They just push back into place.
Tamper resistant bits are standard sizes - there is just a small post in the center that the bit goes around.

 

The bit needed is a T-20 - if you just want to buy one and not a whole set.

 

Hi Tim,

Thanks again for your response.

Trying to remove the trunk / boot liner, noticed the clips are pulling out of the trim rather than the metal boot. Will obtain a trim removal tool, not to damage the fittings.

In the mean time, have traced the wiring, will check 12 volts is present when the brake pedal is pressed, at the connector for the suppressor, which is connected in parallel. (looks like this connector is behind one of the access points in the trunk / boot.

This should at least confirm if a 12 volt supply is present, then remove the high level light to replace.

Thanks again . . .

 

Had that same problem when I removed my trim, and one of the clips pulled off. Used some gorilla glue to reattach it. Make a note of which way the fastener should be oriented before gluing, as they are not all the same (I think that is to make removing the trim easier, so you can sort of 'pull up' on the trim to release it.

 

Outcome - High Level Brake Light

As new to the Jaguar brand and XK model, a huge thank you to all who replied and forward ideas and suggestions - much appreciated

Fault - Not Working

Initially tested 12 volt supply from brake light switch,

which I believe feeds to the fuse / junction box behind the middle seats.

Plug CA129 / pin 9 - cable colour NR - Brown & Red

This cable routes to a connection CAS54 and splits

1/ - to main Plug BL001 / pin 1 still as Brown & Red -

the other side of the plug (all cables are now black) from vehicle to trunk / boot via rubber hose

into boot plug TL001 / pin 10 - output back to Brown & Red colour

final plug TL008 / pin 1 - (which is the plug the high level light unit plugs into)


2/ - the other feed from connection CAS54 is to a suppressor - which is connected in parallel with the high level brake light

the plug for this is located behind the access panel in the boot / trunk - which is handy to test if a 12 volt output without removing the trunk / boot interior panel or seat section.

this plug is CA188 / pin 1 - again Brown & Red ( +12 volts ) - pin 2 is Black & Green 0 volts - with the brake pedal pressed - 12 volts should be present


in this case - 12 volts was present when the brake pedal was pressed - handy with assistance pressing brake pedal whilst testing with meter


therefore removed the boot / trunk interior panel to access wiring,


The tricky bit, as no assistant to press the brake pedal,

To test, connected a 5 watt bulb (should be ok for testing, even though the LED is only 2.1 watts) to the final plug for the high level brake light, with extended wires, with the boot up,
placed the test bulb over the edge of the boot / trunk so visible from drivers seat whilst pressing the brake pedal.


Hey Ho, the test light lit when brake pedal pressed,


Removed the high level brake light unit (with x 2 screws Torx 20), ( gently removing those light screw covers, to all the female XK owners, girls a warning, you will break a those lovely nails)
and fed with an independent 12 volts supply - No Joy


Replaced High Level Light Unit - Result - working just fine and dandy


Thanks again to all for info and advice . . .

Great Forum

 

Glad you got it going BJ and thanks for posting the outcome. Your details will help others I'm sure.

 

Okay, resurrecting a thread here...
I used the above info and discovered that the Suppressor is bad on mine. It's a tiny thing, built into a short harness about 12" (30mm) in length. A 220µ capacitor on a long skinny circuit board.
I've searched and can't find the harness online. Part #9W8318K891BA
Anyone have a lead on this?

 

If you can access the circuit board why not attempt to replace the faulty capacitor Cee jay?

 

I took off all the heatshrink and found this mess, I don't think the capacitor is the weak point...

The scratches on the upper left are from getting the h-s off, and it's only superficial.