Time for lighting maintenance on the instrument panel

Did some research and found this upgrade for the listed bulb, C15788 for the instrument panel.

Anybody bought or tried these out? Here’s the URL. https://duckduckgo.com/?q=jaguar+bulb+c15788&t=brave&iax=images&ia=images&iai=https%3A%2F%2Fi.ebayimg.com%2Fimages%2Fg%2FCmYAAOSw8SdeqtT9%2Fs-l300.jpg&pn=3

Do you intend these for the backlighting of the dash or for the fiberoptic module? And if the dash, do you intend to remove the green shrouds or leave them in place?

What model Jag are you going to put these on- as they won’t work on an XJS, which takes the small “wedge” bulbs. These look like a replacement for the 2.2 watt screw-in bulbs. Try looking for LLB 504 bulbs.

The back-lighting is what just went out and I can’t see the four gauges in the middle at night. Any idea of how many bulbs I need to change them all out?

The instrument panel for a 1990 XJS V12 Conv.

Avoid any LED rubbish of such in instrument panel. You can buy 5watt (i think) direct replacement bulbs for your instrument panel. You have 2W by factory default (anyway, several times lower than those on the market today). My dimmer is barely above the minimum now. With LED-crap your dimmer won’t work. Don’t bother with quantity - those are being sold in packs of 20. It’s called 501 capless bulb. For fibre optic you can use strong directional LED in alloy heat sink.

Forgot to mention - better equip yourself in silver conductive paste or at least copper paste. The old pcb-on-mylar thing may be the reason of unequal brightness level. You eill need to remove/clean some brass nuts as well…

There ya go, black rectangular things are the bulb holders

I presume that I have the correct bulb called out. Can you give me a source for the greater than 2W bulb you are suggesting?

Oh and another question. The bulb is into a screw in holder and not some kind of press in set up?

Those black bits are holding the bulb inside and they’re pain to remove (use WD40 on both shorter sides). There are two spring blade terminals (shorter sides) that presses into the tape so remove it gently or you will damage/crack the copper-printed tape. All goes in/out quite tight (tape pressed under the blwck bits)

I count 4 bulbs. Is that correct? But then it doesn’t really matter. If I buy more than I need, like you say, Big deal. But I’m wondering if the bulbs I have found which show a threaded mount are the right ones. Could you please verify that. I have just never seen bulbs in an instrument cluster that have threads.


I have found over the past 20 years of Jaguar ownership that simple mysteries like this can be solved quickly and easily if you have the correct documents. In this case the answers to your questions about your instrument panel bulbs are easily found on page 2L18 of the XJ-S Parts Catalogue (RTC9900CA). There are five Instrument Illumination Bulbs, P/N C43898 in the instrument panel. They are held in place by Bulb Holder, P/N 13H 5270 J. Attached is a picture of some C43898 bulbs and bulb holders that I harvested from a used instrument panel that I purchased on eBay.

The XJ-S Drivers Handbook for our 1990 XJ-S convertible shows that these are 2.2W “Capless 504” bulbs.
Having the Drivers Handbook and Parts Catalogue handy saved me a lot of time and money because I can find the parts I need and shop quickly for them using the correct part numbers.


I really appreciate that. Those are the types of bulbs and holders that I’m used to seeing. Thank you very much.

There are 5 of those as far as I remember. If you look at the top right corner of the photi above - there’s a slot with one disassembled already (showing how flexi tape goes under the bulb holder). Use 301 type - will last longer.

My 1992 facelift has 5 bulbs for gauge illumination, and there are 20 positions for warning lights, although not all are used do to variations in specification. I replaced them all with LED units and it was a huge improvement. You can pick the colour of the gauge illumination, and the warning lights become magically visible during the day.

The warning light LEDs I got from Amazon didn’t fit the sockets very well, so I swapped the LEDs into the old holders. One thing to look out for is the LED polarity. Unless they have a built in bridge rectifier, you will need to check the orientation of each one. It is non-obvious from the flexi-circuit which ones are switched to earth and which are switched to power.

Hi CosmoXL,
Do you have a p/n for the LED bulbs? I would really appreciate knowing that. Thanks, Paul

I got these from Amazon UK, should be available most other places.

Warning lights
Gauge lights

As above, you might not get a good fit and may have to repurpose the old bulb holders.

Thanks, much appreciated. I will now be able to tool up and have the replacement parts all together. I don’t know about most of the members here but my XJS is my daily driver so when I tear something down I have to have all parts, etc. ready to complete the job or find another car before starting to tear things apart.

I have been tied up with so many things, I finally got around to the dashboard lights. What I found is that everything was OK except for dirt and corrosion here and there. I also found that there are a lot of cheap LED replacement bulbs that I found only last for 6 to 12 months. I would definitely buy the $10ea ones from Sylvania. I cleaned everything up with contact cleaner and verified with a digital VOM using the audio sound for clear connectivity.

I also found that the last two vertical gauges, the gas and voltage are backlit very poorly with the baffle design but I wasn’t about to take everything apart again. The bulb was operating.

The easiest way to find the correct bulb is the standard for the industry is 194 which is the nomenclature for the mounting base.

While I was there I also lubed the speedometer which has now been unstuck for 9 months with whale oil because I had some from working with watches, the mechanical kind many decades ago.