Hi. I have a car alarm from Design Tech (#20930) installed in my restored 66 Mustang. I'm now trying to hook up the Starter Kill wire. To do so, it says I need a standard Bosch style SPDT (Single Pole Double Throw) 30 Amp relay. I've looked on the internet trying to find the right relay and any other parts I may need. This is what I found:
* 12VDC 5-PIN RELAY SOCKET w/DIODE (Pre-wired relay socket with diode across the coil. Designed for use with starter kill circuits. Three 12" leads. For use with 5-pin Bosch type relay.)
* 12VDC AUTOMOTIVE RELAY SPDT 30A (This Bosch type 12V, 30A relay is popular in automotive sound and security installations. SPDT. Plastic housing with mounting tab.)
* 12VDC BOSCH RELAY SPDT 30A (This 12V, 30A relay is popular in automotive sound and security installations. SPDT. Plastic housing with mounting tab. Bosch #0 332 209 150. Made in Germany.)
Do I need the relay and the socket, or just the relay? Do I need the diode? Also since I'd rather not disturb the condition of my restored Mustang, is it necessary to cut wires to complete this installation, or is there another way? I would appreciate your advise. Let me know if you need any other information. The installation manual is located at:
https://www.designtech-intl.com/pdf/manuals/20630v4-1.pdf
Thanks,
Tom
You are going to have to interrupt the starter power source at some point to wire in the relay. I understand your reluctance to cut into the existing wiring and create an unsightly connection. My suggestion would be, if you have a neutral safety switch connected to the transmission, you could disconnect one side of wiring there and wire the relay in-line at that point. Another option would be to disconnect the starter wire at the back of the ignition switch and wire the relay in at that point.
Most of the relay switching applications can usually get by with a relay that does not use a diode, but I would try and find a relay that did have the diode already connected for this application, or any relay connection that is hooked to the alarm brain, so that the alarm is protected from any electrical kickback when the relay coil power collapses.
For a starter kill circuit, I normally would not use a relay plug connector if I was using a relay which already came with the diode build in, however, you could use a relay plug connector that already has the diode prewired to it and then you could use the standard 5 pin bosch relay, which would be easier to replace should the relay ever fail.
I order my relays from Parts Express, but if you only need one, I would try your local audio or alarm installion company, I'm not too keen on using the relays that most of the local auto parts stores. If possible, try and use a good quality brand relay and you shouldn't experience any problems down the road.
https://www.partsexpress.com/webpage.cfm?did=7&WebPage_ID=3&catid=47&ObjectGroup_ID=31