15 Jeep SRT Radiator Fan not working P0148

Hi all,
My 2015 Jeep Grand Cherokee SRT was involved in a front end accident. No airbags were deployed. The one issue I’m having is the radiator fan doesn’t turn and my scanner shows P0480 (Cooling fan 1 control Circuit/open. I got three fans the one involved in the accident, after market and one that came from a Dodge Durango. None of them worked. The fan comes with positive, negative and another very small wire. Here’s what we did so far... we check the fuses Rad fan, high speed and low speed relays. I am pretty sure the plugs have power from multiple test I have done. We tried to jump the radiator fan-none worked. We     actually replaced the water pump since the pulley was wobbling a a bit. I tried to reset the codes, but it doesn’t erase. Lastly I did check continuity on the small wire and the fuse and not sure if it’s working as I should. When I start the car it beeps for about a second. Surely it’s going to a system check? I figure the last thing it could be is a bad ECU since I can’t even clear the code as well.  

Anything help

I'd start with load testing the two large cables at the fan connector. Use a headlight or other similar heavy load. One wire to red, the other to black. Does the bulb light brightly? If yes, I'd consider those circuits good. If not, find out if the power or ground is missing.

The small wire is a PWM signal from the PCM directly based on commanded fan speed. I found this step in the P0480 flow chart. See attached.

Check for voltage on the small wire as directed. I don't know what you're going to see? :silly: But the flow chart seems to be happy with just about any. Let us know what you find and we'll go further.

Hi Tyler,

Thanks for your quick response!

I did test the connectors and I’m not sure if they’re working. I checked with a circuit reader ( no light ) and also an multimeter which is reading .040v with the vehicle set to run. Unfortunately I don’t have a scanner with an actuator test/active test.

Also there was no reading on the smaller wire.

What voltage do you have at the computer? Connector C1, pin 30.

If you have higher voltage at the computer, but only 40mV at the fan connector, then you have a wire problem. It could be a broken wire or high resistance somewhere along the wire.

If you have 40 mV at the computer then check for a short to ground. Unplug the computer and unplug the fan to isolate this wire and check for continuity to battery negative. The only good reading is OL.

I checked the ground continuity by using the ground immediately from the radiator plug and it gave a good reading. I’m not sure how to go about testing the computer. I have concerns of possibly damaging the computer or other components. If you could kindly give directions.

Thank you!

——- I’m having someone take a look at the car to check wires and what not in a day or two. I'll keep everyone posted.

I'm sorry Jeffrey, I'm still not clear. Does one of the big wires light a test light connected to B-? Does the other big wire light a test light connected to B+? If so, we'll consider those circuits good enough for now.

The small wire will only show voltage during commanded fan activation, per the flow chart. The PCM may be doing some kind of circuit check, as you noted, and shutting the circuit off in response. Does your scan tool have bidirectional capability?

I’m using a light tester that you would you conveniently use for checking fuses. When I use it to check the connectors (positive, negative and the smaller wire) for the radiator fan it doesn’t light up at all no matter if you just start the car or if the car is running and or at optimal temp for the radiator fan to come on. I do not have a bidirectional scanner at the moment. The tool I have are a multimeter, a pretty good diagnostic scanner, circuit tester to test short/open wire and of course a 12v light tester.

So no pins on the fan connector light up with the test light connected to B-? That means you're missing a power feed, at least.

Recheck fuse #4 in the remote jump start post box.

I had someone check it out and they say it’s the Radiator Fan Cooling module. I did check the post and it actually didn’t light up immediately. After messing around with it did finally light. Not sure if that could play a part. I’ll take a better look to see if I can find the module, because I didn’t think it had a separate module. “Right rear of radiator) (w/350w)” How would I know if it’s a 350w, it doesn’t say it any where on the old fan.

Just found out apparently the computer isn’t the problem. SIA Electronic is where I sent it in. They had it for over a month!!! My only other option seems to be the dealership. They should be able to diagnose it at least.

  Your Jeep may have the 2 speed cooling fan, not the variable speed.