I have a 2000 Dakota 4.7 V-8 4x4 and cannot get the electric radiator fan to work. I have read several threads and cannot seem to find any that fit my issue. I have tested and swapped the relay and 30amp fuse, changed the 10amp fuse and nothing. I tested the fan directly with 12v power and it runs, even tested the power at the relay and fan runs. When I checked the power distribution center with a voltmeter I get 13.4v at the "power all the time" pin, 13.4v at the "power on" pin and 5.3v at the wire from the PCM pin. I tested the ECT, and replaced it to be safe, and it checks out (temp gauge is working). When I unplug ECT the fan does not come on, it should according to other threads for safe mode.
What am I missing? Is this a PCM problem? I was thinking the PCM would only power the relay when the ECT told it to, but I am getting 5.3v all the time.

 

Is that the only fan you have?

Do you still have the mechanical fan?

The efan is for a backup cooling and for A/C operation so it only turns on when your A/C is used or the water temp hits 210.

If you have A/C turn it on see if the efan turns on.

I dont recommend removing the mechanical fan and only relying on the efan as you never want to over heat the 4.7 even for a minute they always blow out the head gaskets best to keep it cool. This is extremely common and an expensive fix is an extra 5 hp worth blown head gaskets.

 

I still have the mech fan and the problem is running hot in stop and go traffic. I have checked the elec fan with the a/c running and still not working. I just put new heads on it after a small radiator leak lead to warped heads so I want to make sure I have this working.

 

Your mech fan is crap many cheap mech fans are garbage most say stick with an OEM dealer fan.

Seen many having problems with after market fans

 

I have the OEM mechanical fan and fan clutch and electric fan. My problem is the electric fan will not come when the temp gets to 210 or the AC is on. I have tested the entire circuit, including relay, fuses, wires and the fan works when I apply direct 12v power. I replaced the ECT and the relay, but still nothing. Since the circuit tests good is the a PCM problem? Is the PCM not telling the fan to come on?

 

If your seeing 210 you have a problem and its not your efan. Find what the real problem is bad rad low on oil slipping clutch/trans.

00DakDan is the electrical wizard not I

 

I have a new radiator and when I replaced the heads I replaced all the hoses and thermostat as well. The cooling system is working correctly and holds pressure, no leaks. The engine and trans are working great. the temp just creeps up when stopped, goes back down when moving. I have hard wired a toggle switch for the fan and the temp stays normal with the fan running while stopped. What I am trying to figure out is why the fan will not operate like designed. According to the wiring diagram there is only the single relay and fuse. I have tested all of the components and checked the wiring for continuity and everything is testing good, which leaves me to think the PCM is the issue.
On a side note, I have noticed that the CEL is on and there are no codes, stored or pending, in the PCM, which again is making me question the PCM. I replaced the PCM about 2 years ago, it was flashed by the dealer. I know the efan worked because when I first started having temp issues I checked this and it worked. It wasn't until I pressure tested the cooling system that I discovered the blown head gasket.

 

Toss a new temp sensor in see what happens thats what tells the PCM to kick in, the temp sensor is a cheap part I believe. Check the temp sensor wires for corrosion.

 

I also still say your mec fan is not working like it should if it was you wouldn't have a problem or your new rad sucks.

 

The PCM controls the fan. Are you sure you are on the correct pin where you read the 5.3v? Connector 3 Pin 2 is the one you want.

It should NOT have voltage on it when calling for the fan. It goes low. Power feeds through the relay and grounds at the PCM to turn it on.

It will read voltage when the fan is OFF.