I am installing XJ40 Daimler seats in my 64 Jag MK2. I think they are 1990 vintage.

I am trying to determine how to wire the lamps in the back of the headrests over the picnic tables As you can see in the photo, there are three terminals. The small terminal also has a diode. There is no on/off switch. The headrest has a black/pink wire that I am sure is ground. The large terminal has a brown/white wire and the small terminal has a red/light green wire.

I assume that one of the wires connects to the courtesy lights circuit so when the door is open the light comes on?

Note the rotary dial on the right. It operates a “shade” that dims the light. I am not sure about this but when the shade is rotated all the way open it must break the ground contact because the light goes out - so I guess it does have an on/off switch of sorts.

Any ideas about the connections for the brown/white and the red/light green wires in the MK2?

 

Hi Lin,

Figure 10A in the manual at this link shows how the lamps are wired in the XJ40:

http://www.jagrepair.com/images/Auto...ec%20Guide.pdf


You are correct that the lamps come on with the other interior lamps when the doors are opened, then extinguish several seconds after all the doors have been closed. That function is controlled by the CPU or microprocessor, which provides a path to ground via the Interior Lights Relay.

The lamps can also be manually turned on with that rotating wheel, which connects the lamp to ignition switched ground A.

Battery power is supplied via the Seat Back Lights Relay.

Cheers,

Don

 

Thank you Don,
Now all I have to do is figure out how to adapt these to my MK2 wiring. Obviously there is no ECU :-). This is a good start. I appreciate the help.

Lin

 

I'd start with a bench type power supply (battery charger) and make a note of what does what when hooked up to power or ground and simply duplicate those conditions when you wire it up to the car - pretty straightforward?

Saw your blog, nice work!

btw, built a new harness for my TR6 during the rebuild, increased gauge by 1 size, all worked well but had a bit of a hard time passing through the various body panels as the diameter of the harness had increased slightly!!

cheers

Larry

 

Idiot thought, but could you simply jumper the appropriate wire into the courtesy light circuit and the switched wire to the nearest hot? Just putting it out there....

 

Thanks guys! I am going to set up a bench test arrangement later today. I will let you know how I come out.

Jerry,
your suggestion is pretty much what I will try to duplicate on the bench. I also need to incorporate the interior lamps light switch on my central gauge panel.

Larry,
Thanks for the compliment on my website. I still have a long way to go! The larger wires going forward through the firewall don't seem to be an issue, but the wires going through the LH and RH sills may be an issue. We will see!

I told my wife to just shoot me if i ever want to do a "modified" restoration again. One thing always leads to another thing. never neat and easy!

Lin

 

Set up a little bench test with the rear interior lamp, the B/C pillar lamp and the headrest lamp. Got everything working and discovered a few things.

My B/C pillar lamps, which are new from SNG Barratt, have an on/off slide switch unlike the originals. Any way, as a result of my test I discovered that the on/off switch on the B/C lamp also turns on the rear lamp and the headrest lamp when the central gauge panel interior lamp switch is in the off position. Nice, I guess, that a passenger in the rear seat can turn on all the courtesy lamps with a simple switch at the B/C pillar. Unlike the original B/C pillar lights, these new ones have three wires - a black ground wire, a brown wire for constant power, and a brown/white wire to the door switch. I wired the headrest light the same as the B/C pillar light.

I also discovered that the headrest lamp works just like the other lamps EXCEPT that when all lamps are off, you can rotate the “dial” rotary switch and turn on just the headrest lamp by itself. The other lights do not come on.

With the door closed, the central gauge panel interior light toggle switch turns on the B/C pillar lamp, the rear interior lamp and the headrest lamp.

The problem with the new B/C pillar lamp and with the headrest lamp is that if turned on and left on the battery will drain. While it is not likely that one would leave on four interior lights without noticing, it would be very easy to leave on a headrest lamp. Hmmm. Will have to work on that.

Lin