Could someone tell me how I can test the Lucas and Fiamm relays for working order, before I do something dumb to them? If it ever stops raining here, I am planning to insert the electrical system back into the car. The testing of the relays I can do on the bench. One is missing the masking looking tape around the winding, what now? Thank you. Regards, Alberto Image Unavailable, Please Login
Alberto, relays are nice simple devices, very easy to work with. To test them, first locate the two coil terminals. In the case of Lucas relays, they are labeled W1 and W2. 1. Measure the resistance between them, should be somewhere around 70 to 100 ohms. (If they read just a few or 0 ohms, the coil is shorted. Don't use. If it reads open circuit, coil is open, again don't use.) 2. Apply 12 V to the coil terminals. (Polarity does not matter with vintage relays - no diodes in them). You should hear the relay click. That means the relay armature is operating. Then go on to test the contacts: 3. Locate the the two terminals for the N.O. (normally open) contact. In the case of a Lucas relay, they are typically labeled C1 and C2. They should read open when the relay is off, and closed (0 ohms) when it is on, but it is better to test them with a typical load: Connect 12V to C2, for example, and a 12V light bulb to C1. It should light up when you activate the relay. That means the relay is OK. Simple, no? Variations: The above description applies directly to the four terminal relay in the bottom of your picture. It is probably a standard single pole N.O. relay. To test the five terminal relay, proceed the same way, except connect a second test lamp to the fifth terminal C4. That lamp will either light up when the relay is off (N.C) or when it is on (a second N.O.). Try to find the wiring diagram for that type of relay, to know what to expect. If it does not light up at all, the relay has a bad contact. The two three-terminal relays in your picture, have one side of the coil internally connected to the supply terminal C2, so coil resistance is measured between C2 and W1(?). That makes them even simpler to test. Connect +12V to C2 and the test lamp to C1. When you connect the W1 terminal to ground, the relay should activate and the test lamp light up. Hope I did not complicate things too much. Regarding the relay with missing tape around the coil: It should not matter for testing. The wrapping is there only to protect the winding and secure it against vibrations. It should be wrapped if you plan to install it in the car, though.
What a well timed thread! I have some Lucas 6RA's to test as well! While we're on the subject - Is there a source for reproduction Lucas relays that actually look original? The newer ones I've gotten recently all have cheesy decals instead of the stamped logo of the originals.
