Ram B1500, B2500, B3500, 1999-2003

Electric Engine Fan

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Vehicles equipped with the 2.5L engine use an electric fan for engine cooling. Models with the 4.7L engine incorporate an auxiliary electric fan to aid low-speed cooling. Fan operation is controlled by the PCM through a relay located in the Power Distribution Center (PDC). The PDC is in the engine compartment on the left fender inner shield. The location of the fan relay is given on the inside of the PDC cover.

The fan relies upon several inputs to determine operation, notably the coolant temperature sensor.



The fan will run whenever the engine is running and the air conditioner compressor clutch is engaged.
 
When the air conditioner compressor clutch is disengaged, the fan will run at vehicle speeds above 40 mph if coolant temperature is above 230ºF (110ºC). The same is true of vehicles without air conditioning.
 
The fan will turn off when coolant temperature drops to 220ºF (104ºC).
 
At speeds below 40 mph, the fan turns on when coolant temperature reaches 210ºF (99ºC) and turns off when coolant temperature drops to 200ºF (93ºC).
 
The fan will not run during engine cranking.
 

Vehicles equipped with the 2.5L engine utilize an electric fan for engine cooling. Models equipped with the 4.7L engine have an auxiliary electric fan to aid low speed cooling. These units are not serviceable. If defective, they must be replaced. See "ENGINE ELECTRICAL" for testing procedures.

The following procedure refers to 2.5L models only. On the 4.7L, the electric fan is removed with the radiator. Refer to "Radiator."

Fan Switch



Testing
  1. If the fan will not run, the easiest test is to disconnect the fan motor lead and apply 12v across the connector. Note polarity as shown in the illustration. If the fan runs, the problem is in the circuit or upstream components.
  2.  
  3. With the ignition and air conditioner ON , check for voltage across the wiring harness side of the fan motor connector. Note polarity as shown in the illustration. There should be 12 volts at the connector. If there is, the problem is the fan motor. If not, suspect the relay, circuitry, or other upstream component.
  4.  
  5. The PCM will set a diagnostic trouble code in the memory if it detects a problem in the fan relay or circuit, although a DRB scan tool is required for this analysis. If not available, proceed as follows:
  6.  
  7. Check fuses: there is a 10A fuse in the junction block and a 40A maxi fuse in the PDC.
  8.  
  9. Locate the fan relay in the PDC (location is shown on the cover). Apply 12 volts (with 14-gauge wire) to relay terminal 87 . If the fan will not run, check for an open condition in circuits C25 or Z1. If the circuits are okay, replace the fan.
  10.  
  11. With the ignition key OFF , check for battery voltage at circuit C28 relay terminal 30 . If no battery voltage is present, check for an open or short condition in circuit C28 between the PDC and relay.
  12.  
  13. With the ignition key in the RUN position, check for battery voltage at circuit F18 relay terminal 86 . If no battery voltage is present, check for an open or short condition in circuit F18 between the junction block and the relay.
  14.  



Click image to see an enlarged view

Fig. Note fan polarity before testing

Removal & Installation



  1. Disconnect the battery negative cable.
  2.  
  3. Disconnect the fan motor wire connector.
  4.  
  5. Remove the fan shroud mounting clips connecting the shroud to the radiator.
  6.  
  7. Remove the fan and shroud from the radiator as an assembly.
  8.  
  9. Installation is the reverse of removal.
  10.  

 
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