Engine cooling Fans come on after hood closes?

SHARLEE KUCHYNKA

MEMBER
2004 CHEVROLET SILVERADO
5.3L
V8
2WD
AUTOMATIC
130,000 MILES

My husband has the truck listed above 1500, we had the engine cooling fans replaced about 2 years ago and they are only supposed to come on when the truck gets over 210 temperature. Now when we close the hood the fans turn on. And when we open the hood, they shut off. These fans were put in specifically for his truck because it is high performance. Anyway, we woke up to the truck battery being drained this morning and now we know it’s because of the fans staying on. The truck started just fine yesterday, and fans acted as they have been, only coming on when the temp got over 210. So, I’m not sure if this would be a relay problem or a circulation issue with something not being ground off properly. But why would it just all of a sudden do this today? He can’t drive it down the road without the fans draining the battery since they are staying on now when the hood closes.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,909 POSTS

It sounds like the ground is loose for the fan control module (aftermarket, correct?) Or the fan controller is bad. If you can upload images of the system I can help.

Here is more information:

It sounds like there may be an issue with the cooling fan circuit in your 2004 Chevrolet Silverado. The fact that the fans are turning on when the hood is closed and turning off when the hood is opened indicates that there might be a problem with the fan control system. Here are some potential causes for the sudden change in fan behavior:

Faulty Fan Control Relay: The cooling fan system in most vehicles is controlled by a relay. If the relay gets stuck in the closed position, it could cause the fans to run continuously, regardless of the engine temperature. A faulty relay can be caused by wear and tear or an electrical issue.

Cooling Fan Sensor/Switch Issue: The cooling fan system uses sensors or switches to detect the engine temperature and signal the fan to turn on when it reaches a certain threshold. A malfunctioning sensor or switch may be sending the wrong signals, causing the fans to operate incorrectly.

Wiring or Grounding Problem: There could be a wiring issue, such as a short circuit, damaged wire, or poor grounding, which is causing the fan control system to behave abnormally.

Aftermarket Modifications: Since you mentioned that the fans were replaced with high-performance ones, it's possible that there was an issue during the installation or with the aftermarket fan controller, causing the unexpected behavior.

Please go over these guides and get back to us.

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Saturday, July 29th, 2023 AT 2:58 PM

SHARLEE KUCHYNKA

MEMBER
4 POSTS

Yes, we figured it was having to do with fan control module or wiring. Please let me know if these pictures help any further. If you need another picture, let me know.

Images (Click to make bigger)

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Saturday, July 29th, 2023 AT 5:54 PM

SHARLEE KUCHYNKA

MEMBER
4 POSTS

Also just wanted to let you know we did feel the metal part on the latch for the hood and it was very hot after only running for a couple min. Nothing else around it was hot like that so yes it tells me that there’s some kind of charge going through it. Your reply did help give us a place to start and my husband is going to try to check the things you mentioned above.

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Saturday, July 29th, 2023 AT 6:04 PM

SHARLEE KUCHYNKA

MEMBER
4 POSTS

My husband is going to take it up to the mechanic that has worked on the fans before but idk if it’s safe to drive with a charge going through the hood.

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Monday, July 31st, 2023 AT 6:57 AM

KEN L

MASTER CERTIFIED MECHANIC
42,909 POSTS

It sounds like the controller is bad or there is a bad ground on the system. Thanks for the images. I would remove the aftermarket fan system and install the factory unit; it will cool much better. Please let me know how it goes.