Hi. I own a 2000 Dakota SLT 4x4 4.7 I went out to my truck this morning to go to work and the battery was dead. This afternoon I went out to it and jumped it and as soon as we hooked up the jumper cables we noticed the electric fan came on. Without the key being in the vehicle. Does this sound like a thermostat problem? I pulled the 30amp fuse out to keep it from running right now. Would it hurt if I didnt have the electric fan for a while? I am stationed in Eastern NC and it is hot here. Any help would be appreciated.

 

sounds aftermarket.....

 

dodgehas a bulletin to reprogram the ecm for 2000 dakota's with cooling fans that run continuosly-I'm not sure if it applies to your vehicle. I would call the nearest dealer with your vin # and see if it applies. You can also request a goodwill warranty if it is no longer under factory warranty. If that doesn't work contact dodge corporate customer service and be nice but persuasive!!! good luck.

 

The fan should be factory. If I recall the 4.7 4x4 Autos came with an electric rad fan. The fuse is listed on the cover of the fuse lid as a factory installed fuse. Would re-programming the ecu work if it runs even after the vehicle is shut off and the key is removed?

 

I just went out and unplugged the coolant temp sensor and it still comes on when I put the fuse in. Is that right? or does that mean the sensor is bad?

 

Thebulletin is for reflashing the pcm which is responsible for commanding the fan on (or at least the relay for it). It is probably some sort of issue with a glitch in the software causing the relay to be energized when it shouldn't be.Unplugging the temp sensor fools it into thinking the engine is hot (open in ckt). If you grounded the sensor return wire (2 wire sensor) it would make the pcm think the vehicle is cold (-30c). You could try a new sensor as inexpensive as they are, but I don't think that is the case.

 

Ok. I am gonna ask the dumb question. Where can I find this bulletin?

 

I'm not sure if it is on the net. I can access it through my companies Fleet repair information. I will try to get it posted for you asap.

 

OOPS! Reread bulletin and it only applies to the 2.5L and it is for running continously until key off.
However the service manual says that it is either the coolant sensor, fan relay, or the pcm. it is a 2 wire sensor,unplug the sensortake a paper clip and jumper the two terminals(in the wire harness)together and see if it shuts the fan off. if so, replace the coolant sensor. If not check the relays under the hood, usually the A/C and cooling fan or fuel pump or some sort of relay will be the same in the electrical center. Swap it with one of those. If the fan then shuts off , but your A/C (for instance) runs continously, then you found the culprit. if none of the above shuts it off, then you may have an ecm problem, but not likely. You could have an open ckt between the pcm and the coolant sensor.Good luck!!!-Jeff master ase certified tech.

 

FIXED! Thanks for the help. Ended up being the relay. I pulled it ou and swapped them around. Then I put the old one back in and it works fine now. I think I may replace it anyways. Just to be on the safe side. Thanks for the help.

Scott