Jaguar XK’s use a boot lamp switch made by Lucas with (according the SPC’s) part number 31185-94L and Jaguar code C.2873. This switch is of the “push type” and known as Lucas model 94.
I had some problems with this switch (related to the contact part connected to the wire) and tried to find more information in the Lucas catalogue. I was unable to find any reference of a Lucas Switch 31185: it is not mentioned in Catalogues 400D and 400E. Also XK 120 Explored nor XK 140 Explored did not provide more information.
The Lucas specification for the Jaguar XK 120/140/150 over the period 1948 -1957 refers to Lucas Switch 31222A . The boot lamp switch on my 1954 XK 120 shows the same code stamped: 31222 with a D suffix by 1954 (see photo).
By 1960 the 31222 number had been replaced by Lucas 31404.
Lucas number 31185 as mentioned by Jaguar, may have been a specially assigned code for Jaguar with e.g. a piece of wire already attached to the switch. There are more examples of unique Lucas codes for Jaguar.
My actual question: does anybody have a detailed picture of the (separate) brass contact ring with lug that is connected to the electrical wire? See photo of 31404. I probably have to make one myself….
Better make a few; mine are missing the solder tab. It is a metal tab ring folded over and capturing an insulating fiber ring. Here are both sides of it.
One side makes electrical contact with the base body when the door is open.
There is another insulating fiber washer above it by the nut.
These come in at least two varieties, long and short button.
Lucas manuals describe the one used on the Mk V as number 359236 which is a somewhat “heavier” version, apparently also used on the early Mk VII models and various Rolls and Bentley models It has a much thicker flange at the front. See pics.
The 359236 seems however not identical to the “longer” version you show, which may well be the later 31404 model. It is described by Lucas as having a “longer plunger” and the number is normally stamped on the outer tube. Can you read the number?
Some correct original switches are offered on eBay presently for “silly prices” (€ 85 - € 100 a piece). Coventry Auto Components offers a switch for an acceptable price (GBP 36) but without the essential metal tab ring, so that doesn’t help…
I guess with the availability of modern glues it must be possible to use a cable eyelet which is then glued to the (existing or new) insulating fibre ring, taking care that it is not touching the plunger. Will do some experiments in this direction.
Found a set of 4 pieces Lucas 31404 in good condition complete with cable and metal contact with solder lug. Is anybody interested to buy these jointly? Price would be around € 25, GBP 20 or $30 each excl postage. Contact me via private mail.
I’ve noticed before some discrepancies between Lucas publications and Jaguar SPCs. The Mark V SPC says the door switches (aka step switches for the map light) are C.2658 or 31222/A which is marked on mine. The boot light switch for the tool tray is called out in the SPC as 31185 or C.2614 but carries the number 31175A on the body.
I would imagine these numbers were derived from Jaguar’s purchase records.
Both my door switches are a little bit bent on the flanges. I would call it a design flaw, insufficient strength in bending.
It may be that Lucas was producing the thicker flange version as a replacement, and offering it to the trade in their publication, rather than simply recording the thin flange version which Jaguar had bought from them for the Mark V.
As readers may have understood, the subject of these boot switches is not easy to clarify as there were a number of different switches involved and (as Rob said) Jaguar and Lucas don’t always agree on the part number.
The list below is a kind of summary, listing all such Lucas switches that have been used by Jaguar.
A short update. With the help of Roger King we managed to obtain the (officially Lucas recommended) replacement Switch 31404 (which in fact existed already in 1954). See “exploded view” of Lucas 31404.
Lucas 31404 is indeed a full replacement for the earlier switches Lucas 31185 (Jaguar C.2873) and Lucas 31222 (Jaguar C.2658). The only difference is that the later 31404 has an additional O ring on the plunger (see photo).
I guess this Lucas switch type was used more and more as a Door switch with a much higher frequency of operation compared with a boot lid switch. This made greasing necessary and an O ring would help to keep the grease in the housing (which was complete identical for all the mentioned switches; see photo).
please don’t laugh was setting up the striker tab to boot light switch on a car with new boot lidtimber etc etc hw do I see if it is striking and operating correctly!!!
pity I can’t upload the video
A very interesting and helpful thread, this switch operation really had me puzzled until I leant about the (missing) contact under the insulating washer. Thankyou all.
Next question, can anyone give me some reasonably accurate dimensions for the position of the boot (trunk) light?
