Bench Testing A Ford Relay (A Step-by-Step Guide)

Relay Bench Test

OK, it's time to get our hands dirty and bench test the relay.

You'll need a power source to activate the relay (during the test) and this power source will be your vehicle's Battery.

As mentioned in the previous page, you'll need three very important things:

• A Multimeter (analog or digital).
• Two jumper wires with alligator clips on the ends.
• Maybe a helper.

Alright, here are the test steps:

1. Connect terminal 2 of the relay to the battery's Ground Terminal with a Jumper Wire.
   • You can use the photo of the relay with all of the connections, since the photos show the actual test.
   • If you don't have such a jumper wire (with alligator clips), you can run down to your local Radio Shack (even Walmart) and buy some alligator clips and make your own jumper wire.
2. Connect male spade terminal 1 to the battery's positive (+) terminal. This will energize and activate the relay.
   • It's normal to hear a small clicking from the relay when this connection is made.

3. With your multimeter in Ohms mode, measure the resistance across the relay's terminals 3 and 5 with the multimeter leads (as seen in the photo).
   • It doesn't matter which color lead goes where, since the polarity does not matter for this test.
   • You may need a helper for this operation, unless your multimeter leads have alligator clips on the end of the leads.
4. Your multimeter should show continuity. If it doesn't show continuity, recheck all your connections and retest.
5. Remove and reconnect the jumper wire to terminal 1 several times, as you eye-ball the multimeter.
   • When the jumper wire IS NOT connected to power, the multimeter should show NO CONTINUITY.
   • When the jumper wire is connected to power, the multimeter should show continuity.

OK, let's take a look at what your test results mean:

CASE 1: Your multimeter showed continuity. This tells you that the relay is OK and not the cause of the problem.

CASE 2: Your Multimeter DID NOT show continuity. This tells you that the relay is bad and needs to be replaced.