THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

Spay the whole switching unit out with CRC Switch Cleaner ~ great stuff.

Hi. Just a comment on relays:
Glyn wrote « Somebody might well have cobbled a relay into the lighting circuit to fit brighter higher current draw lights to the car.»

Another reason to fit relays is to minimize voltage drop to the headlights. ( John mentioned a headlamp switch gunked up with old grease). Have done this to several old / half old cars. But then you would put an electrical wire of sufficient size the shortest way from supplier to consumer with a relay on the way. ( not behind dash ). And have had up to almost one volt improvement at the headlights. And then of course I’m convinced the headlights seems brigther!

Harald.

thanks John
ill try that,
it would be nice to have an easy fix for a change

I seem to recall from many decades ago I had trouble with the headlamp switch. Turned out it was all gunked up with old grease (?) that prevented contact in certain positions. I was able to remove the switch take it apart carefully, clean and reassemble and it has been working fine ever since.

thanks for the info!
i will check things out at the weekend

And remember to slide the picnic tray out & remove before you attempt any of this.

Somebody might well have cobbled a relay into the lighting circuit to fit brighter higher current draw lights to the car. If the car is original you might have 2 blown sealed beams although it would seem unlikely. What happens when you turn on the lights & push the dipswitch? 4 blown filaments would be even more unlikely.

Thanks for the better pic Rob. I could not find one.

I will go with Glyn on this and say there are no factory fitted relays in the lighting circuit from factory. The wiring is very basic and you just had a wire from a live on the fuse box via the light switch direct to the front lights. That is not to say that a replay has not been fitted retrospectively and hidden behind the dash.
The only way to get behind the glove box is to remove the top dash wood which is held in place with four 7/16 nuts. One accessed from inside the glove box, two by lowering the facia panel down and the forth is equidistant from the side of the car as nut one but up under the dash beside the steering wheel. Once the top is removed you can remove the glove box fascia and glove box liner to look down into the void behind the glove box to see where the noise is coming from.
The picture below shows the relay that Glyn is referring to but as he has stated this is for the heated rear screen. The picture shows the void behind the glove box which can be reached once everything is removed.
[attachment=0]DSCF6048a (2).jpg[/attachment]

The only relay near the glovebox is one to dim the heated rear screen indicator light when you turn on head lights. The headlights are direct switched by the main switch that you turn with the levered knob.


[attachment=1]Heated rear screen relay..JPG[/attachment]


[attachment=0]Heated rear screen circuit..JPG[/attachment]


http://www.jagstyperegister.com/images/maintdocs/S-type-wiring-page.jpg

on switching from sidelights to headlights theres a clonk coming from the glovebox area
could it be a relay thats malfunctioning? if it is where is it located?
i would be grateful for any advice