How To Test The Radiator Fan Motor (1997, 1998, 1999 3.8L Ford Mustang)

This tutorial will help you test the radiator fan motor on the 1997, 1998, 1999 3.8L V6 Ford Mustang.

Testing the radiator fan motor involves two basic tests. One is an amperage draw test and the other is a bench test.

Both tests are explained in a step-by-step way so that you can find out if the radiator fan motor is bad or not.

Contents of this tutorial at a glance:

  1. TEST 1: Testing The Amperage Draw Of The Radiator Fan Motor.
  2. TEST 2: Applying Power And Ground To The Radiator Fan Motor.
  3. 1997 Radiator Fan Motor Wiring Diagram.
  4. 1998-1999 Radiator Fan Motor Wiring Diagram.
  5. Where To Buy The Radiator Fan Motor.
  6. More 3.8L Ford Mustang Tutorials.

TEST 1: Testing The Amperage Draw Of The Radiator Fan Motor

Testing The Amperage Draw Of The Radiator Fan Motor. How To Test The Radiator Fan Motor (1997, 1998, 1999 3.8L Ford Mustang)

Over time, the radiator fan motor's bearings wear out and cause the fan motor's shaft to encounter an excessive amount of friction as it turns.

The end result of this is that the fan motor needs more current to overcome this friction.

This excessive current draw will eventually blow the radiator fan motor's fuse or burn out the radiator fan motor relay (which is inside the Constant Control Relay Module -CCRM).

The best way to find out if your Ford Mustang's radiator fan motor is consuming too much current (and thus defective) is to do an amperage draw test.

This test simply involves measuring the resistance of the fan motor and then using Ohm's Law to determine its amperage draw (Ohms Law: Amps=Volts ÷ Ohms).

NOTE: On the 1997 3.8L Ford Mustang, the amperage draw can not be over 60 Amps. On the 1998 and 1999 3.8L Ford Mustang, the amperage draw can not be over 30 Amps.

Let's get started:

  1. 1

    Disconnect the radiator fan motor from its electrical connector.

  2. 2

    Place your multimeter in Ohms mode.

  3. 3

    Measure the resistance of the radiator fan motor across pins 1 and 3 with your multimeter (see photo above).

  4. 4

    Divide your resistance value by 12.5. The result of this calculation is the amount of amperage the fan motor is using.

    To be a little more specific: Let's say that the resistance reading was .4 Ohms. This is what the math would look like: 12.5 ÷ .4 = 31.25 and this would translate to 31.25 Amps.

  5. 5

    Amperage Draw Specification:

    1997 3.8L Ford Mustang: No greater than 60 Amps.

    1998-1999 3.8L Ford Mustang: No greater than 30 Amps.

Let's take a look at your test results:

CASE 1: The amperage draw of the radiator fan motor is within normal parameters. This the correct and expected test result.

The next step is to manually apply battery power and ground, from your Ford Mustang's battery, to the fan motor itself. For this test go to: TEST 2: Applying Power And Ground To The Radiator Fan Motor.

CASE 2: The amperage draw is higher than specified for your 1997 or 1998-1999 Ford Mustang. This test result tells you that your Ford Mustang's radiator fan motor is defective and needs to be replaced.