Service Engine Light

[smt 59]

I have a challenge in regards to the service engine light coming on three times now with a P0480 code for cooling fan relay or fan speed output circuit although the cooling system is working fine. Each time I check and then clear the code, it’s fine for a while then it happens again. Called a contact at the dealership and they automatically go to replace the clutch fan assembly for a fee of about $1100,00 and I ask will this fix it and they reply no guarantee!!. So today I’m driving home from a dealership(not GM) after test driving a car and sitting at a red light and all of a sudden all my warning lights come on and on the driver information centre it says check oil level and then ENGINE FAILURE with the truck stalling. Oil was and is fine as all fluids as I have babied this truck since new so WTF is going on? I did piss off a lot of drivers behind me as I shut her down and let everything reset, it ran fine for the rest of the day until I got home and ran a scan and no codes at all. Anyone had the same issues or experiences.
Any thoughts?

 

[Mooseman]

The electro-viscous fan clutch is known as a flaky part, which is why GM went back to thermal in 2008. Yours is probably on it's way out. I'd get it tuned and get a thermal instead. Much more reliable.

For the oil pressure, 99.9% of the time it's the oil pressure switch. If the engine isn't making any noise, that's the usual culprit.

 

[mrrsm]

What can happen is that the Temperature Sensing Circuit for the FAN to turn on at HIGH Rate will want to invoke when the engine temperature reaches 223 Degrees Fahrenheit... which WOULD happen when you are stopped at a Red Light long enough to keep ambient air from passing through the Radiator. But the problem is that if the PVC Tube that is supposed to be designed to protect that harness to the connection point of the body of the Fan Center has chafed through the wiring harness ...right where the bottom of the PVC Tube has been bouncing up and down for the life of this component ... then the Ground and 5 Volt Signal Wiring will be incapable of responding to and from the PCM Commands to lock up and spin at a fast enough rate to pull air through the Radiator and drop the temperature to nominal ranges.

The whole design idea of course is to NOT have the entire mass of the fan resisting the rotation of the engine unnecessarily...and scavenging horse power as a result. Without having that Chafe Point insulated... the wires tend to wear through and lose their insulation to the point of shorting out. The Dealership KNOWS this... but they cannot make any money by telling Customers the Truth about such relatively easy to solve problem(s). Here is an image of how this harness can go sideways ...and fail:

 

[smt 59]

Thank you the quick responses guys, so in regards to the two types of fan clutches do you typically have a choice when purchasing, the tune is an easy fix, and as well were the wires are likely worn can I get in and insulate with electrical tape? The oil sensor sounds like an easy fix also.

 

[mrrsm]

For the Wire Harness Repair... It will probably require all the labor ordinarily needed ...just short of a Water Pump Replacement ... to get enough access to the Fan Area and get intimate with the harness insert points. If you look at the cutaway design in the image... you can see how far down the wire damage can go inside. But if you can see where the rubbed away areas are and get enough radial working room around each of the wires... you could cut some over sized strips of Heat Shrink Insulation and once everything in the bundle has been separated well... Hit it with a Heat Gun just long enough to get them secured. See @Matt 's Epic Water Pump and Fan R&R FAQ in the Stickies for the Best Instructions on how to do this preliminary part of the job.

If you try to use common Electrical Tape... it will make Gooey Mess that will melt and fail in the ambient heat of the Engine and Radiator in short order. They also make a nice Stretchy Silicone Tape to repair Radiator Hose leaks that will work... if you can get enough room to wrap the wires properly. One last ditch attempt can be made with some Black Liquid Tape applied when the wires are moved apart, coated liberally and then allowed to dry well enough over a full day to solidify and make them all behave enough to properly communicate with the PCM from then on:

Black Silicone Tape:

https://www.amazon.com/dp/B00K5GW67O/?tag=gmtnation-20

Black Liquid Tape:

https://www.amazon.com/dp/B01HCX4MC4/?tag=gmtnation-20

 

[smt 59]

Not quite as easy as I would like it to be, if I’m stripping it down I may as well put in the new part, I see the aftermarket ones are a lot cheaper to buy hopefully they are good quality.

 

[Mooseman]

Hayden are the go-to for us here. Best price-quality ratio. Dorman is junk.

To get it tuned, http://www.lime-swap.com/ does it for $99. You can also have other stuff tuned like torque management, shift firmness, remove speed and rev limits. Jeremy is easy to work with.

 

[Drec]

Out of curiosity, what years/models are we working on here?

 

[smt 59]

Great information, I will check into the Hayden, as for the tune I have a guy relatively close to me that did my tune a while back and I will just take it back to him.

My Voy is a 2005, it’s in my profile . 170,000 KMS or 105,000 miles in imperial

Thx all, will keep you posted on progress as usual.

 

[smt 59]

So the shop that I deal with is recommending the Behr unit, I am seeing on line they have a thermal reverse rotation unit that has all positive reviews. Never heard about the reverse rotation thing though. Is this a thing with our trucks? And it looks the same as the original unit with wire harness.

 

[Mooseman]

If it has a wire harness, then it's not a thermal unit. Thermal is 2008-2009 TB. Fits exactly like the original without the harness. You would need a tune so the CEL won't turn on for the missing harness. If you have a choice between Behr and Hayden with price being a factor, you can safely go with Hayden.

 

[smt 59]

Great thanks Mooseman, I will let the shop know to order in a Hayden.

Happy Canada 🇨🇦 day