Radiator fan not working

Tiny
FRANKRP
  • MEMBER
  • 2004 HYUNDAI SANTA FE
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 80,000 MILES
My engine ecm is not giving a gnd signal to cooling fan relays #1 and #2 to turn the fans on high with the a/c. Can you tell me if I can install a used computer without having to bring it to the dealer, would like to try it at least for t/s purposes. Warrantee over on ecm Hyundai telling me I have to bring it to them. Thanks Frank.
Friday, September 3rd, 2010 AT 9:42 AM

6 Replies

Tiny
DAVE H
  • MECHANIC
  • 13,384 POSTS
A replacement computer needs to be reprogrammed i'm afraid. A dealer will have to do this for you. It could be a faulty engine coolant temp sensor causing the fault. Not giving correct signal to ECM
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Thursday, September 16th, 2010 AT 7:20 PM
Tiny
JC64323
  • MEMBER
  • 1 POST
  • 2003 HYUNDAI SANTA FE
Replaced temperature sensor and relay fan still wont come on it only comes on with ac?
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Monday, November 11th, 2019 AT 6:24 PM (Merged)
Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
So only one fan comes on and that is when the a/c is on, correct? Each fan will have its own relay. So you may have just changed the relay for the a/c fan.
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Monday, November 11th, 2019 AT 6:24 PM (Merged)
Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
Actually there are three relays and they are all located in the junction block, I do not have any pics, on fan is the condensor fan, and another has to be a/c fan relay, and the third is radiator fan relay. I dont know why they need to make these things so complicated
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-1
Monday, November 11th, 2019 AT 6:24 PM (Merged)
Tiny
ADAMHYUNDAI
  • MEMBER
  • 2 POSTS
I've got the same issue. So replaced the coolant temperature sensor and relay, tested the thermostat, tested the radiator fan resistor and fan hilo, flushed the cooling system. The fan will only turn on if the ac is on but still will not turn on when the engine gets hot. But if I jump the pins with a wire the fans turn on.
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Tuesday, December 31st, 2024 AT 5:54 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
I would connect a scanner to see how hot the PCM says the engine is, the fans should come on at about 212 degrees.

Here is a guide that can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go over this guide and get back to us.
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Friday, January 3rd, 2025 AT 11:22 AM

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