Diagnostic Aids

This test is only intended to diagnose the following:

• Cooling fan harness circuits.
• High Cooling Fan (HFAN) control relay.
• Low Cooling Fan (LFAN) control relay.
• Powertrain Control Module (PCM).
  Fig 1: Fan Control Relay Harness Connector ID (HFAN & LFAN - Villager)

  Courtesy of FORD MOTOR CO.
  CIRCUIT PIN IDENTIFICATION
  
  

  Circuit	Breakout Box Pin No.	PCM Pin	Wire Color
  HFAN	13	C275-13	Brown/White
  LFAN	14	C275-14	Blue/Orange

1. Check Relay Function
   
   Turn ignition off. Install scan tool. Turn ignition on. Enter SIMULATION TEST. Access PID for circuit in question. Using scan tool, attempt to command cooling fan on. If cooling fan does not operate normally, go to next step. If cooling fan operates normally, fault may be intermittent. Go to CIRCUIT TEST Z. See TESTS W/CODES article in ENGINE PERFORMANCE section.
2. Check Power Feed Circuit To Relay
   
   Turn ignition off. Disconnect harness connector of relay in question. Turn ignition on. Using a voltmeter, check voltage of PWR circuit at relay harness connector in question. If reading is greater than 10.5 volts, go to next step. If reading is not as specified, repair PWR circuit. Restore all electrical connections and repeat QUICK TEST.
3. Check Signal Circuit For Open
   
   Turn ignition off. Install Breakout Box (014-00950), leaving PCM disconnected. Using an ohmmeter, check resistance between breakout box test pin of relay in question and signal circuit at harness connector. If resistance is less than 5 ohms, go to next step. If resistance is not as specified, repair open in signal circuit. Restore all electrical connections and repeat QUICK TEST.
4. Check Signal Circuit For Short
   
   Ensure ignition is off and breakout box is installed with PCM disconnected. Disconnect harness connector of relay in question. Using an ohmmeter, check resistance between breakout box test pin of relay in question and chassis ground. If resistance is greater than 10 k/ohms, go to next step. If resistance is not as specified, repair short to ground in signal circuit. Restore all electrical connections and repeat QUICK TEST.
5. Check Cooling Fan Motor Operation
   
   Turn ignition off. Ensure breakout box is installed with PCM disconnected. Turn ignition on. Using a fused jumper wire, ground breakout box test pin for relay in question. Relay should click and fan should run when grounded. If relay does not click, replace relay. If relay clicks and fan runs, replace PCM. Restore all electrical connections and repeat QUICK TEST.