[bigcat24]

I found this article on the fan system, but I don't completely understand what it is trying to say. Currently, my cooling fan 25a mini fuse keeps blowing on about a monthly basis... i'm trying to figure out why. Does anyone have any insight?????????????????

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Engine Cooling Fan Description - Electric

Operation

During low speed operation, the engine coolant fans receive power from a 30 amp MaxiFuse. The PCM supplies a ground path for the cool fan 1 relay through the coolant fan #1 Relay Control circuit. This energizes the relay coil, closes the Fan 1 relay contacts, and supplies current to engine coolant fan motor #1. The ground path for cooling fan #1 is through the series/parallel cooling fan relay (cool fan 2 relay) and engine cooling fan motor #2. The result is a series circuit with both fans running at low speed.

During high speed fan operation, engine coolant fan motor #1 receives power from the 30 amp MaxiFuse. However, engine coolant fan motor #2 receives power from the 25 amp fan #3 fuse. The series/parallel relay coil is supplied battery positive voltage from the 20 amp PCM BAT fuse.

To command high speed cooling fan operation the PCM first supplies a ground path for the cool fan 1 relay through the Low Speed Fans control circuit. After a 3 second delay, the PCM supplies a ground path for the cool fan 2 (series/parallel) and cool fan 3 relays through the High Speed Fans Control circuit. During high speed operation, both engine coolant fans have their own ground path.

Important
When certain diagnostic trouble codes (DTCs) are present, the PCM may command the cooling fans to run all the time. It is important to perform the Powertrain On-Board Diagnostic System Check prior to diagnosing the engine cooling fans.

The PCM will complete the ground path for cooling fan relay #1 under any of the following conditions:

When engine coolant temperature exceeds 106°C (223°F)
When A/C is requested and ambient temperature is more than 50°C (122°F)
When A/C refrigerant pressure is more than 190 psi (2 volts)
When the ignition is OFF and engine coolant temperature is more than 140°C (284°F)

For high speed cooling fans operation, the PCM will delay control of the cool fan 2 Relay and cool fan #3 relay for 3 seconds. The 3 second delay ensures that the cooling fan electrical load will not exceed the capacity of the system. The PCM will complete the ground paths for cooling fan relays cool fan #1, cool fan #2 Relay and cool fan #3 under any of the following conditions:

When engine coolant temperature exceeds 110°C (230°F)
When A/C refrigerant pressure is more than 240 psi (2.5 volts)

 

[bigcat24]

Odd thing is that before, I have just replaced the fuse and all is well... check engine light goes off and the fans work fine. However today at lunch I replaced the fuse, but the check engine light is still on and the fans still aren't working...

 

[scott00]

I have same problem , what solved yours

 

[Ejbiers]

Did you get the code for the check engine light?

 

[scott00]

Replacing the fuse clears the check engine light, will it be helpful to get the code the next time the fuse blows? After I replaced the fuse I shorted the two terminals on the relay block terminals 87 and 30 and this makes the respective fan turn on, (tested both fans) however it was cold weather and will test again when it is warmer to make sure that the fan doesn't seize under hotter conditions. Can both a bad fan and bad fan control pop the fuse? Also could a bad relay pop the fuse? In case the relay is intermittent I am going to switch out with the equivalent relay on the dash fuse panel since that is easy to do.

 

[kingnutin]

The code will still be stored in memory unless it gets cleared by a scanner or disconnecting the battery.