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TR6 TR6 Horn Relay Problems

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phil56

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I have searched through many forums and have been unable to find anyone with a similar problem. I am on my third new horn relay from Moss and have been unable to get the horn to work with the new relay. The horn works fine with the old mechanical relay. I have transferred the four wires over from the old relay to the same connectors on the new relay and have double checked the wiring against the wiring diagram. For the first two relays I disconnected the battery and transferred the wires, then reconnected the battery. When I pressed the horn button, the horn came on and stayed on even after I released the horn button. I had to disconnect the battery. After that, when I reconnected the battery, the horn would only click when I pressed the horn button. For the third relay, I left the battery connected, connected the purple wire with two connectors to W1 and C2. When I connected the PY wire to C1, without the PB wire to the horn button connected, the horn sounded. My car is a 1973 TR6.

I notice that for the 70 - 71 models with A type overdrive, this same relay is used for the overdrive, but connected differently from the horn relay. As a horn relay, C1 is used for the load side, while for the overdrive, C2 is used for the load side. For a mechanical relay, I dont think this makes any difference. However, I am wondering if the new relay is solid state and it makes a difference which way around C1 and C2 are connected.

Any help someone can give me would be appreciated. Thanks
 
What relay, precisely, did you get? I've never heard of a commercially made electronic relay, although it is possible to make one (I have). By "mechanical relay" I assume you mean the standard type of electromechanical relay, yes?

If it's an electronic relay, the connections almost certainly will matter, but the manufacturer should have provided information on hooking it up. For an electromechanical relay, the switch connections are interchangeable. So are the coil connections.

The only horn relay I found in the Moss catalog is the metal-box thingy used in all kinds of TRs. That's not electronic. I had one in my TR4A, and I removed it after it shorted the +12V to the case, blowing a fuse. Not what I'd call a finely made component.

You can use an ordinary automotive relay if it doesn't have to look original. That's what I have.
 
Thank you for the reply. Yes, I mean electromechanical, referring to the old relay. I am trying to change the relay because, when I got the car, the relay in it did not work and I took it apart and fixed it as a temporary measure, and the box has a lot of surface corrosion and looks awful.

I think we are talking about the same relay. The new relay I have is Moss part number 542-170, which lists in the Moss TR250 and TR6 catalogue to be used for the A type overdrive and the horn. On the Moss web site, it shows this relay is used for a long list of Triumph, MGB, Jaguar and Austin Healey applications. Moss did not provide any instructions for connecting it, so I am going by the wiring diagrams. I am suspicious that this new relay is electronic. With no power applied to the relay, I get conductivity between C1 and C2. It is all over the place between 3 ohms and 100 ohms and depends which way I measure the resistance. An electromechanical relay would just have open points, no conductivity. I think probably it should be connected as shown for the overdrive, but I dont want to do this and smoke test it, and have to pay for another relay. On the other hand, if it shows that it is OK to connect it with C1 and C2 reversed for the overdrive relay, then I should be able to connect it this way for the horn? Perhaps I should go back to Moss and find out if it is electronic.

Again, thanks for your reply and any other insight you might be able to think off.
 
Not trying to Speak badly but you got it from Moss.
A story to tell ; MyTR6 1973 heater cable broke so I did off and on by hand until a club member was ordering parts ( MOSS ) I ask him to add a new cable for me. It worked a few times then failed! it just a steel wire how hard could it be. so by hand for a few years . so I order a cable for BPNW two week ago and replaced it. To end; the wire was several sizes thinner on the Moss unit and the set screw would not hold the wire. With the stories from other club members I could go on. If you are not looking OEM get a relay from auto parts store or just clean and paint yours I only have one spare so can not help there. MF
 
Thank you for the comment. This TR6 is my third restoration in the past 10 years. The previous two were Fords. I have encountered some quality control issues with Moss parts that are very similar to issues I encountered with similar parts for the Fords. If I figure this relay problem out I will post the results.
 
I do not think it is always the parts suppliers ( Moss, TRF etc.) it's where they get there after market parts China Mexico . The UK for parts still has best quality
 
Do you have "TRIUMPH TR250-TR6 ELECTRICAL MAINTENANCE HANDBOOK" by Dan Masters ?
He has some helpful information about horns and relays in his most invaluable book.
A real timesaver:

MG, Triumph, Austin Healey, Jaguar Parts & Accessories | Moss Motors

Find all your British car restoration parts at Moss Motors. We offer parts for MG, Triumph, Austin Healey and Jaguar with fair prices and a large inventory. Two shipping warehouses for fast delivery.
mossmotors.com mossmotors.com
 
I really doubt that you have an electronic relay. Your description makes me think that the contacts are just not closing or opening properly.

If you're not concerned about original appearance, you could use something like this:

TE Connectivity V23234-A1001-X036 High Current Mini Relay | Waytek

TE Connectivity V23234-A1001-X036 High Current Mini Relay, SPDT, 40A, 12V is in stock ready to ship. Purchase today!
www.waytekwire.com www.waytekwire.com
 
Thank you everyone for your comments. Sometimes it takes a bit of conversation to get me thinking. I found a Moss video on youtube about how a relay works. It is electromechanical, I can hear a clicking sound when I apply power to the W connector lugs. The contacts are not doing what they are supposed to be doing according to the video. This is the third relay in a row that Moss has sent me that is faulty. Looks like they got a bad batch that they have not tested. To me, it is one thing to trouble shoot parts that are in the car to find out if they are working properly, but I dont think we should have to be trouble shooting new parts. We should be able to install them and have them work. If suppliers want to get their parts from the lowest cost manufacturer, that is fine, but I think that they should be doing some quality control and not just passing through poorly made parts to the consumer. Just my humble opinion.
 
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