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Discussion Starter #1
I have a 2016 Malibu LS and the coolant fan does not come on when the A/C is on. In older vehicles this was a usual problem with the fan relay. Looking at the underhood fuse block, I do not see a relay. Does anyone know what is going on with the lack of a relay and this problem?
 

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I finally found a wiring schematic for my vehicle. The radiator/coolant fan is a simple circuit with a fuse, fan motor, and ECM. So it looks like the ECM controls the fan operation and no relay exists.
 

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How big is the fuse? That could indicate if there's a relay inside the ECM or elsewhere, even if the drawings don't show one.

It could also be a MOSFET controlling it by using PWM.
 

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The fuse is large at 50 amps and it is located in the underhood fuse block. My problem is that the fan does not come on intermittently when the A/C is turned on. This is strange as the engine never gets hot when the fan is not operating at idle. I saw a TSB about the connector at the fan having issues with moisture, but it usually would show a DTC. I want to check this connector but it is difficult to access.
 

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The BCM uses relays that protect circuits with only 10A fuses, so 50A is massive!

I would hazard a guess that with a fuse that big, it'll be operated through a relay of some sort, or an entire module of its own.
 

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Discussion Starter #6 (Edited by Moderator)
The BCM uses relays that protect circuits with only 10A fuses, so 50A is massive!

I would hazard a guess that with a fuse that big, it'll be operated through a relay of some sort, or an entire module of its own.
DrivenDaily: Thanks for your input. I got the schematic from bbbind/tsb-wiring website. It may be suspect about accuracy. I tend to agree with your assessment. I lost all my contacts working with GM and think that I need to have someone at at dealership access their TIS database for more accurate diagnosis and included wiring diagrams. If you know another way to access diagnosis information, please let me know.
 

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There is no way the ECM is controlling the fans without a relay. ECM controls relays to control loads in high amperage circuits. I don't have a diagram for your car but GM uses high and low speed motors for cooling. I use Alldatadiy.com for my ''fleet'' and their diagrams are very specific. Worth the few bucks for a subscription if your doing your own wrenching.
 
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