Here's a breakdown of how to test a relay:
1. Identify the Relay:
* Consult your owner's manual or a wiring diagram: This is crucial. It will tell you which relay controls what and where it's located. Relays are usually found in fuse boxes under the hood or inside the cabin. They're small, square or rectangular components. The diagram will also show you the relay's pinout (which terminal does what).
* Visually inspect the relay: Look for any obvious signs of damage, such as burnt contacts, melted plastic, or loose connections.
2. Gather Your Tools:
* Test light: A simple 12V test light is ideal.
* Multimeter (optional but recommended): A multimeter provides more accurate readings of voltage and continuity.
* Wire with alligator clips (optional): Helpful for connecting the test light or multimeter to the relay terminals.
3. Testing the Relay (using a test light):
This method is simpler but less precise.
* Remove the relay from its socket.
* Identify the relay's terminals: Most relays have 4 or 5 terminals. A common configuration is:
* 85 & 86: Coil terminals (control circuit). One is connected to ground and the other to a switched power source (usually from the ignition system).
* 30: Power input (constant 12V).
* 87: Normally open contact (power output when the relay is energized).
* 87a: (If present) Normally closed contact (power output when the relay is *not* energized).
* Using your wiring diagram, identify the power input (30) and output (87) terminals.
* Connect one lead of your test light to a known good ground.
* Connect the other lead of the test light to terminal 30 (power input). The test light should illuminate.
* With the test light still connected to terminal 30, briefly connect the 85 & 86 terminals to a 12V source (like a battery). You'll need to use your jumper wires to achieve this (be careful to not short anything!). The test light connected to terminal 87 should illuminate briefly now. If it doesn't, the relay is likely faulty. *Always disconnect the jumper wires immediately after applying 12V*.
* If both 87 and 30 light up when both 85 and 86 are connected, the relay is good.
4. Testing the Relay (using a multimeter):
This method is more precise.
* Set your multimeter to continuity mode (usually a diode symbol).
* Check continuity between terminals 30 and 87. There should be *no* continuity when the coil is not energized.
* Connect a 12V source briefly to terminals 85 and 86. There should now be continuity between terminals 30 and 87.
* Check for continuity between terminals 30 and 87a (if present). There should be continuity when the coil is *not* energized, and no continuity when energized.
Interpreting Results:
* If the relay fails any of these tests, it's likely defective and needs to be replaced.
* If the relay passes all tests, the problem likely lies elsewhere in the circuit. Check fuses, wiring, and the components connected to the relay.
Important Considerations:
* Incorrect testing can damage your vehicle's electrical system. If you're not comfortable performing this test, take your S-10 to a qualified mechanic.
* Always refer to your vehicle's wiring diagram. Relay pinouts can vary.
* Double-check your connections to avoid short circuits.
This detailed explanation should help you test the relay. Remember safety first! If you're unsure about any step, it's always best to seek professional help.
