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2008 Malibu LTZ 3.6 VVT

Been chasing a "creeping" gauge overheat issue. Just noticed that the passenger side fan runs fine at low speed but when the system goes into hi speed mode, it shuts down and I'm left with just the driver side fan which runs correctly in either hi or low. I traded the relays around and that did nothing. Why is this fan cutting off when told to go to hi speed? Thanks.
 

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I have checked all the relays and they are all good. What I have discovered is it appears I have no power coming out of the 30 slot for Fan Relay 2. Evidently that relay is bypassed entirely in low mode and both fans are run in a series just using Fan Relay 1 so that they only use 6 volts each. Fan Relay 2 is only used in parallel mode so both fans can get the full 12 volts for high. The 87 slot is grounded so I am now looking at the 30 slot on the fuse block for Fan Relay 2 to find out why its not getting any power. Any advice still appreciated.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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There are 3 relays and 2 fuses.

Relays 1 and 2 directly control power going to each fan, and the other relay is the Serial/Parallel relay that controls whether they are hooked up as low speed or high speed.

The right-hand fan (passenger's side) should never be grounded on terminal 87. Instead, it will have either full power for High or the side of the left fan that becomes grounded on High or placed in parallel on Low. However the S/P relay has a wired ground on 87.

By your description, the 30A fuse on the right fan is blown or the power to it has failed. If the latter is true, you may have a fuse box that has failed internally. If that's the case, it may be repairable or could need to be replaced.

69217
 

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It ended up being the J Fuse to Fan 2 (#18). I got a little caught up in the way the system works and overlooked the simplest of things. Thank you for the diagram and help!

BTW, that 87 slot on the fuse block is grounded on both fan 1 and fan 2. I tested it and for power and ground before I put the relay back in. When running in low in a series, the fan 2 relay is bypassed.

Here is a good video that explains it around the 4 min mark.

 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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I kinda thought it might help to see it rather than spend all day trying to explain it. Glad it helped!

If you test 87 on the right fan with either a VOM or light, it'll show a path to ground because the right fan is wired to ground on the other side of the motor. The motor's windings are made of wire, so whether it's a large current flow or just a minor current from a VOM or test light, it's still a wire. It operates the same way that early GM front side markers did when the turn signal was blinking.
 
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