Horn relay
 

Greetings!

Ii have a question about horn relay, Lucas 6RA. The horn has stopped working. The same relay connects to a host of other things like alternator, ignition, heater fan etc. if those other things work can it really be a faulty relay for the horn?
i jumped a live test wire to the horns and they toot. I have checked the fuse.

thanks in advance.

neale.
jaguar xj6 coupe 4,2 1977.

Hi, substitution is always the best test. which fuse did you check exactly?

in later cars, there is a horn/claxon inline fuse above the battery in a plastic fuse holder with thick brown wires.

how did you test the horns? by themselves direct from the battery?

also you might try an existing similar relay In the car with the same number of connectors temporarily to confirm. Look behind the dash for a similar relay and at the bulkhead.

Hard to say without a diagram. "Connected to" the relay is not the same as controlled by the relay.

There are several variants of the 6RA. However, the terminals marked with a "W" (W1, W2, etc) are on the control side of the relay. Whatever wiring attached to them pertain to actually operating the relay.

The terminals marked C1, C2, etc are on the load side of the relay. Whatever wires attached to them pertain to the circuits being switched on-off by the relay and the power source that feeds them.

Cheers
DD

https://cimg7.ibsrv.net/gimg/www.jag...615e68f53.jpeg
Lucas horn relay, looks nothing like the one in the parts catalogue or the drawing in workshop manual. However nifty line drawing. Thank you for the explanation, wires can be connected in but not operated by the relay. I never knew that. I understood that the relays job was to prevent switches being burnt out by higher amps and thats about it, oh and that it is basically a switch in the form of a coil.

Two lucas relays are available as replacements when I search with 4 pins. One is jaguar / MGB compatible for 20 euro and the other is jaguar / Aston Martin for 60 euro. Neither of them look like this one, the mg one is square the Aston is oblong but actually looks like the one in the workshop manual. I think 60 euro is insane for a horn relay.

in answer to how I tested the horns. I pulled off the feed wire and jumped a live direct from the battery and they peeped. I changed the fuse at the main board. It also effects stop lights and the feed to the wash bottle. The feed to wash bottle pump motor
Checked out fine with my voltmeter. The wash pump
motor doesn’t work either, another part to swap out, that is easy...

I plan to visit a few places locally with my relay. Maybe a local chap can test it for me and/ or supply a replacement.

Thank you so much for the input,

Well, to start off, that pictured relay does not look like the one on the right wing of my 83 wuzza 6.

Neat schematic as do many on the relay 85-86 on that one is the control/trigger circuit. 30/51 - 87 is the load leg.

As I recall, the relay on these cars completes the ground leg of the load circuit.

Do you have Jaguar schematic publication S 57. I think it is available here. It will clarify a lot.

Relays have intrigued for decades. since circa 48, I installed one to "brighten" the lights on my 37 Ford. needed l badly, even if it sported "modern" sealed beams in lieu of old tech bulbs...

Carl

Then round black Lucas pictured is not a "6RA" type relay and can be replaced (if you don't are about looks) with a garden variety "Bosch Style" relay with the standard 30-85-86-87 terminal designations. If you get one with an "87a" terminal, it'll work fine as well. Should be easy to find

https://www.fcpeuro.com/products/saa...CABEgJSefD_BwE

If you want the round style Google "DRC132 relay"

Here's one

https://www.ebay.com/itm/DRC132-horn...-/112097900406

Cheers
DD

Might not help in this case, Carl. The S57 covers the Series III cars. The Series II cars, such as the OP's 1977 model, are different in many respects

Cheers
DD

I stand corrected!!! I missed the ID at the lower left of the original post

So, this might be a place that the schematics in the Haynes book might help.

I do suspect, but surely don't know, that the SII horn circuit is the same as the one in SII cars.

Electric work today or tomorrow. Left brake light out!!! The unique jaguar system advised me of it!!!
But, alas, not which one!!! Son was by and we checked all. He did not know that the ignition had to be on to test!! Jaguar fired right up. Hissy fit seems fixed.

He is messing with the starter on his ancient big fork lift. A curious critter derived from a WWII vintage Dodge Weapons carrier!! Over decades, t acquired a 51 Plymouth engine and a Chrysler starter... Solenoid atop similar to jaguars and GM cars. Issue with bad ring gear..

We debated as to whether the starter would turn in the same direction on + or minus battery connection.. It is + ground now! I say nope, + or - it will crank...


Carl

I would've be inclined to agree, Carl. but PerErs mentions a lot of other things piggy-backed to the horn relay which are not found in the Series III set-up, so I have doubts.

Cheers
DD

Thank you for all the input. I have pulled out the wiring diagram from the original handbook which folds out to something that covers the best part of an average coffee table. Studying that now but with the advice I already have shall see what I can turn up in my locality on Monday before online purchasing from the UK. Incidentally the cheaper online replacement has the same numbers as to the existing black one. Will let you know what develops.

very best!