2003 NISSAN ALTIMA OVERHEATING

  • Tiny
  • bikerbill34
  • 2003 Nissan Altima
  • 4 CYL
  • 2WD
  • automatic

2003 Nissan Altima, Radiator fans don't come on and engine overheats. What sensor drives the fans?

Monday, December 20th, 2010 AT 10:55 PM

6 Answers

  • Tiny
  • saturntech9
  • Expert
  • 28,250 posts

It's the engine coolant temp sensor.

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Monday, December 20th, 2010 AT 11:26 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,541 posts

That's controlled by something called an "Intelligent Power distribution Module" which is controlled by the ECM after referencing the coolant temp sensor. There are (2) 40 amp fuses to check also.

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Tuesday, December 21st, 2010 AT 12:18 AM
  • Tiny
  • bikerbill34
  • Member

I've checked the fuses, and all 3 fan relays check good. The coolant temp sensor was replaced, so its new. I'm kinda stuck, don't know anything about these japanese cars.

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Tuesday, December 21st, 2010 AT 3:29 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,541 posts

Will any fans come on with the A/C?

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Tuesday, December 21st, 2010 AT 4:02 PM
  • Tiny
  • bikerbill34
  • Member

The only fan that comes on with the a/c is the blower. I bypassed the fan relays and can make both fans come on. However the relays check good. I've got good voltage to the coil side of all three relays, however there is no ground. Im guess ing this is how the ECM controls fan speed, by switching the ground? I'm so lost, LOL

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Thursday, December 23rd, 2010 AT 8:46 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,541 posts

Yes, the ground is the control trigger. You have no way to test that module though.

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Thursday, December 23rd, 2010 AT 9:32 PM

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