2005 to 2007 GM Trucks P0480, P0481 Cooling Fans Not Running

This 07 Classic Silverado had signifcant corrosion on the cooling fan relays and auxiliary relay center. I managed to find a used parts which required splicing 8 wires. Dorman should sell this part as its very common here with the calcium used on the roads. Seemed like every truck I looked at the salvage yards was missing this relay block.

[@55project]

This is just what i was looking for. The good thing is my relays are not rotted out. Thanks for posting

[@PhillipBailey]

You need to turn that relay center over to look underneath for potential damage.

[@oldbiker9739]

gone are the days of direct drive and clutch fans , its amazing were those greenies show up on electrical connections and relays , good find .

[@jgeorges3061]

PHILLIP. Great fix brother and thanks for sharing.

[@Nitroxdude]

Just found this , helped me find my problem, thanks so much .

[@PhillipBailey]

glad it helped you...

[@frankbarone4065]

This helped me out alot, thanks.

[@PhillipBailey]

Glad it helped you.

[@Papichulol8037]

Soooo I didn’t think about the 2 blue wires and I messed it up already. Can someone help me? I got a check engine light on. Should I try and switch the 2 blue wires and see if my check engine light goes away?? That’s honestly my best bet the fans work properly fine, but I do have that check engine light code p0481

[@PhillipBailey]

@@Papichulol8037 try swapping the two blue wires it might fix it

[@lilfargo776]

My truck was parked for like 4 months started back driving it this week, they ac was working fine before I parked it and fans were coming on now they’re not and neither is the compressor..

[@PhillipBailey]

Need to scan it for codes. Check the AC pressures as well.

[@joeysanchez5926]

Good video. I'm having same problem but concerned that it's a bad ground due to excessive rust. When I disconnect the ect the fans run.

[@PhillipBailey]

There are three relays controlling two fans. Disconnecting the ECT will set a code in the PCM which runs all three relays and both fans on high. Chances are there is at least one compromised relay circuit under that auxiliary relay center. I'd take it apart and have a look underneath. Hope this helps you.

[@joeysanchez5926]

@@PhillipBailey I checked the 3 relays today and they're good. Also they don't run when ac is on. The compressor doesn't seem to be working either despite having power and ground. Idk if that's unrelated. I just put in a transmission in it because it had burned up due to overheating.

[@joeysanchez5926]

@@PhillipBailey also it had already set p0481

[@PhillipBailey]

@@joeysanchez5926 P0481 is set when the PCM sees a problem with the high speed cooling fan relay control. Try commanding them on with a scan tool. I've also seen corroded pins at the pcm connectors. It's remotely possible the AC is disabled due to the code but I doubt it.

[@bradellender7969]

I have a po480 code on 2005 chevy silverado 1500. Neither coolant fans or A/C comes on. I changed all the relay switches, temp sensor and thermostat. When using a power probe on the holes where the relay plugs in. I am getting constant power with key off to 85 and 86 with no power to 30. 85 should be the ground correct? Why am i getting power to places im not suppose to and no ground to the one im suppose to? I looked under nothing looks corroded.

[@PhillipBailey]

If its a 4 pin relay it can be installed either way as the control pins are diagonal across from each other. 30 or 87 needs to be live I believe it comes from a fuse.

[@claudettedoucet3646]

Thanks for the video, I am in need of the auxiliary electric cooling fan fuse block for 2005 gmc yukon 1500, do you know where I could get one, gm telling me they don't make them, any help or info thanks

[@PhillipBailey]

You will have to try the salvage yards. You never could buy this from the dealer separately.

[@El_Ceza]

Having issue with fans not kicking on, i replaced coolant temp sensor and relays Customer had already replaced thermostat a couple of months ago with one from autozone i might just change it myself to verify If i disconnect plug from sensor the fans kick on They wont kick on under normal operation though I also checked under relays and sll pins are in great shape no rust or loose connections Also checked all wiring and found no issues im out of options and cant find the issue

[@PhillipBailey]

If disconnecting the coolant temperature sensor causes the fan to run then there is nothing wrong with the fan control circuits. Keep in mind that the open temperature sensor circuit generates a code and the default strategy is to command max fan speed. I believe under normal conditions the fans have three speeds, low, medium and high. With a full function scan tool you should be able to command all three speeds under output control testing. You can also see in the data what speeds are being commanded. Is it setting a code? If so which code? What is the actual problem? Overheating? Coolant boiling? Is the rad cap holding pressure?

[@El_Ceza]

@@PhillipBailey temp climbing past half way with fans not kicking on

[@PhillipBailey]

@El_Ceza but what is the actual engine temperature and does the pcm command the fans on? I've seen Temps about 205f before fan is commanded on. Also the temperature gage may not be accurate. Monitor coolant temp on the scanner in the pcm data and the cooling fan request. You can also see coolant temp reading in the instrument cluster data list. Could be just a slipped cluster needle.

[@El_Ceza]

@@PhillipBailey im going to replaced thermostat right now Then hopefully fixes issue So they should kick on around 205?

[@PhillipBailey]

@El_Ceza I would expect low to come on around 200 to 205 and with the AC on even colder. As I said you need to watch the actual temperature and fan command on the scanner.

[@joerepetur2881]

Is it possible to clean the corrosion or does it need to be replaced? Mine is corroded and I don't have the capability to swap out the box. I also don't think there's a garage around me that'll mess with it other than the dealer. The 1 auto electric shop I found, the number is disconnected.

[@PhillipBailey]

I could not comment on whether it could be saved without seeing it. Chances are it's not salvageable. There must be a capable shop near you. Where are you located? Hard part is finding the used part as its not even sold new.

[@joerepetur2881]

@@PhillipBailey I have only been able to find one used on ebay. I called one shop and I'm gonna try a few others. Going by past experiences, a lot don't want to work on electric it seems. Thanks for the reply, I'm in Vermont.

[@joer6446]

@@PhillipBailey I did find someone and got a replacement harness.

[@Andr1019_]

Got same codes but my fans are constantly runing, relays are good. I’m very confuse.

[@PhillipBailey]

Check for corrosion under the relay center.

[@nicholascarlini5146]

I know this is old but im having this problem, can the person who made this or anyone else who has done it tell me how they got the relay block up from where it is, I can loosen it but it almost seems like the wiring runs under the larger fuse box

[@PhillipBailey]

Lift the other fuse block. It tilts towards the engine away from the fender. The harness runs underneath it.

[@NicholasCarlini-if5lk]

Thank you Philip, I will try that, are there any bolts or anything holding the main fuse block down or should I just be able to muscle it up a bit to get the harness out

[@PhillipBailey]

@NicholasCarlini-if5lk if I remember correctly there are two plastic clips

[@sonnyc3826]

my fan starts up soon as i start my truck and stays ono until it drains the battery i changed and replaced the coolant censor idk which fuse is the rad fan it doesnt say anything remote on the diagram to the radiator fan...only think i can think is a abd thermostat ..it worked for a bit then it started doing the same thing agina wont turn off ..soon as i start the truck fan is on..i have to unhook the battery for it to stop

[@PhillipBailey]

Sounds like a relay is stuck on. The relays are in the auxiliary fuse box behind the main fuse center under the hood.with that fan running and key off try removing the relays one at a time. Look for corrosion under the relay center. You should see the status of the fan relays in scan data as on or off. I doubt its the thermostat unless it's actually overheating but should not stay running after key off. Is it setting any codes?

[@sonnychornley9457]

There's no relay for this fan on my 2005 Silverado. It doesn't even say what one is the fan.

[@PhillipBailey]

@@sonnychornley9457 is it an electric cooling fan assembly attached to the rad in the shroud? If so there should be three relays. What engine do you have,

[@sonnyc3826]

@@PhillipBailey the 5.3 litre i see the one youre using in the video the big one with the "numbered5" relay switch as for the otehr ones maybe theyre coverred and i didnt look good enough i know nothing about truks but im trying to save myself money from crooked shops i think a bad fuse could be my culprit..when i get my truck tomorrow ill take a look i have a feeling shes going to give me soem ridicuous pricetag to fix it when its probably jsut a bad fuse and its stuck on

[@sonnyc3826]

@@PhillipBailey but thanks for replying :)

[@joerepetur2881]

What program or scan tool are you using?

[@joerepetur2881]

I found the answer thanks

[@nicholascarlini5146]

he doesn't show how he got it up in the air so I can splice in the new one

[@PhillipBailey]

Once you remove the brace by the hood hinge you can lift the plastic cover off the fuse panel. Then tilt the fuse panel away from the inner fender. There are a couple clips and it will tilt away from the fender so you can pull the auxiliary relay center out. HTH

[@gameman2936]

How much would a job like this cost?

[@PhillipBailey]

The biggest challenge is sourcing that used part as a new one is not available anywhere. I doubt the entire harness is even available from GM either. If you have a donor harness splicing it it would take around 1.5 hours.

[@DarrylAwesomeOwens]

What tester are you using?

[@PhillipBailey]

I'm using a Snap-on Verus Edge

[@djdarrylowens]

@@PhillipBailey Thanks

[@ashtons3261]

I have clutch fans

[@PhillipBailey]

Some were built with a clutch fan for sure so those won't have this problem.

[@jaredgysen703]

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