Testing The Relay

How To Bench Test A Ford Relay (Large Relay) How To Bench Test A Ford Relay (Large Relay)

Since your Ford vehicle uses quite a few of the exact same type of relay, you can swap them out and in this way test them. But if you're like me, sometimes you need a real test to make absolute sure that the relay is bad.

Well, you've come to the right place for such a test.

You'll need three very important things:

  1. A multimeter (analog or digital).
  2. Two jumper wires with alligator clips on the ends.
  3. Maybe a helper.

OK, to get this test going, this is what you'll need to do:

  1. Place the relay you need to test close to the vehicle's battery (you'll need battery power and Ground for this test).
  2. Using a jumper wire with alligator clips, connect terminal 85 of the relay to the battery's Ground (-) terminal
    1. The photos in the image viewer are an exact representation of what goes where.
    2. If you don't have such a jumper wire (with alligator clips), you can run down to your local Radio Shack (even Wal-Mart) and buy some and make your own jumper wire.
  3. Activate the relay by connecting male spade terminal 86 to the battery's positive (+) terminal.
    1. It's normal to hear a small clicking from the relay when this connection is made.
  1. With your multimeter in Ohms mode: touch terminals 30 and 87 with the multimeter leads (as seen in the photo).
    1. It doesn't matter which color lead goes where, since the polarity does not matter for this test.
    2. You may need a helper for this operation, unless your multimeter leads have alligator clips on the end of the leads.
  2. Once the last connection is made, your multimeter should show continuity. If it doesn't show continuity, recheck all your connections and retest.
  3. Remove and reconnect the jumper wire to terminal 86 several times, as you eye-ball the multimeter.
    1. When the jumper wire IS NOT connected to power, the multimeter should show NO CONTINUITY.
    2. When the jumper wire is connected to power, the multimeter should show continuity.

OK, let's interpret your test results:

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.

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Ford Vehicles:
  • Aerostar (A/C Comp Relay)
    • 1992, 1993, 1994, 1995, 1996, 1997
  • Crown Victoria (ABS Control Relay)
    • 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
Ford Vehicles:
  • E150, E250, E350, E450 (ABS, Horn, HVAC Blower, Fuel Pump)
    • 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Escape (Multi Purpose)
    • 2001, 2002, 2003, 2004, 2005, 2006, 2007
Ford Vehicles:
  • Escort (Rear Window Defogger Relay)
    • 1996
  • Excursion (Door Lock Relay)
    • 2001, 2002, 2003, 2004, 2005
  • Expedition (Door Lock Relay)
    • 1997, 1998, 1999, 2000, 2001, 2002, 2003
Ford Vehicles:
  • Explorer (Anti-theft, Fuel Pump Relay)
    • 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Ford Vehicles:
  • F150, F250, F350 (Active Suspension, Fuel Pump Relay)
    • 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Ford Vehicles:
  • Five Hundred (Multi-Purpose Relay
    • 2005, 2006, 2007
  • Freestyle (Multi-Purpose Relay)
    • 2005, 2006, 2007
  • Fusion (Multi-Purpose Relay)
    • 2006
  • Mustang (Horn Relay)
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
Ford Vehicles:
  • Taurus (Multi-Purpose)
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
  • Thunderbird (ABS Relay)
    • 1994, 1995, 1996, 1997
  • Windstar (ECM Relay)
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
Lincoln Vehicles:
  • Aviator (Multi-Purpose)
    • 2003, 2004, 2005
  • Blackwood (Multi-Purpose Relay)
    • 2002
  • Continental (ECM Relay)
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002
  • LS (Multi-Purpose Relay)
    • 2000, 2001, 2002, 2003, 2004, 2006
Lincoln Vehicles:
  • MKS, MKX (Multi-Purpose)
    • 2007, 2009
  • Navigator (Door Lock Relay)
    • 1998, 1999, 2000, 2001, 2002, 2003
  • Town Car (Air Suspension Relay)
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
Mazda Vehicles:
  • Tribute 3.0L
    • 2001, 2002, 2003, 2004, 2005, 2006
Mercury Vehicles:
  • Cougar (ABS Relay)
    • 1994, 1995, 1996, 1997
Mercury Vehicles:
  • Grand Marquis (Power Window Relay)
    • 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • Marauder (Fuel Pump Relay)
    • 2003
  • Milan (Multi-Purpose Relay)
    • 2006
Mercury Vehicles:
  • Montego (Multi-Purpose Relay)
    • 2005, 2006, 2007
  • Monterey (Multi-Purpose Relay)
    • 2004, 2005, 2006, 2007
  • Mountaineer (ECM Power Relay)
    • 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
Mercury Vehicles:
  • Sable (Multi-Purpose Relay)
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005