Looking for little clarification on P0483 Cooling Fan Rationality Check

bobdec

Original poster
Member
Apr 19, 2013
233
Had DTC pop up twice in the past two months, both times when starting the car the CEL came on immediately. From what I can see from searching reprogramming does not apply to my '07 Envoy. So far I have no cooling or other noticeable problems. Is there any testing I can do, is any immediate action required. Or do I wait for something to happen...
 

triz

Member
Apr 22, 2013
746
It has to do with your Engine Coolant Temp sensor. Most likely its malfunctioning and its not reading correctly. Usually you get that code when it fails to read the temperature rise within a certain amount of time.

It can also be a malfunctioning thermostat not allowing the coolant to flow all the way thru.
 

meerschm

Member
Aug 26, 2012
1,079
you are thinking of a different code.

the P0483 says the fan clutch is not turning as commanded, and is likely bad. you will be ok, as long as you keep moving or if it is not very hot outside. if you end up stopped in the heat, and the fan clutch is not engaging, you will not be able to get the heat removed from the radiator, and the temp will go up.

could just be a loose connector or wire, or could be the fan clutch.

the code for not coming up to temp fast enough is another one. too tired to go look it up just now.

I would get it checked out before you get stuck in summer traffic and overheat. keep an eye on that temp gauge in the meantime.
 

bobdec

Original poster
Member
Apr 19, 2013
233
Just an update, running about a week without setting the DTC. I checked and it's been almost 8 weeks since between two DTC0483 codes. Temp gauge on dash is running between a couple ticks before 210 and straight up at 210. My android Torque App is reading 183-200 coolant temp and transmission is running 175-185. Reading are from in local, stop/start 80-90* F here in Atlanta w/AC always running cold even at idle. I'm keeping a close eye on things, anything else I can do besides changing the fan clutch at this time. Car has 73K mikes, w/dexcool, coolant is clean and level stays rock solid in reservoir. Clutch would be a DIY ( I do all my own work) and usually I don't like to spend money or time on something that is not broken .. My envoy is the newest in my stable at 6 years old, Mercury GM is 10, Chevy G20 Van is 18 and my Z28 is 19. Repair is almost a way of life..

QUESTION.. what scan tool(s) are you using that will provide actual and commanded fan speed data. I do my own OBD1 tuning, and logging. But do not have any OBD2 software yet. Seriously looking at the HP Tuners products for tuning and logging as a learn more about the I6 Vortec . Is there a good data logging/scanning package available in the interim ??? . Not a lot published on what some of the products can do. descriptions seem generic, w/o actual details. Any good tuning forums for the I6 ..been reading the HP one, but not a lot of our stuff in there..
 

bobdec

Original poster
Member
Apr 19, 2013
233
Update 03/05/2014... The once or twice a month P0483's went away when the weather cooled. No DTC's since last October. I'm thinking it was related to having the A/C always on when when starting the truck. Could be the PCM is getting confused by the low coolant temp not commanding any fan, but the A/C pressure commanding an increasing 6 to 25% fan engagement as pressure builds from 105 to 250 lbs pressure. Thinking back the DTC always popped about 15-30 seconds after starting on a warm day with A/C on. Since GM messed with cooling fan software algorithms and hardware changes near the end of the 360 product life, it's hard to pin the '07 stuff down. This is all a guess, will update when the A/C season kicks back in.
 

bobdec

Original poster
Member
Apr 19, 2013
233
Update.. 05/08/2014 . DTC P0483 (Fan Rationality) is back. Will come on randomly within 30-60 seconds after start when the coolant is warm, but below 210 and the the A/C is on. At that time the fan is not commanded on due to engine temp below 210* F, but the A/C is commanding the fan on (6% or more depending on pressure). The DTC says fan is running faster or slower than commanded. Sounds like software getting confused over Coolant and A/C fan requirements. But I can't find any one else (2007) with this problem.
 

IllogicTC

Member
Dec 30, 2013
3,452
bobdec said:
Update.. 05/08/2014 . DTC P0483 (Fan Rationality) is back. Will come on randomly within 30-60 seconds after start when the coolant is warm, but below 210 and the the A/C is on. At that time the fan is not commanded on due to engine temp below 210* F, but the A/C is commanding the fan on (6% or more depending on pressure). The DTC says fan is running faster or slower than commanded. Sounds like software getting confused over Coolant and A/C fan requirements. But I can't find any one else (2007) with this problem.
Or maybe it's expecting, say, 50% engagement and it's getting like 47% or 55% or something. It's engaging but it's not EXACT.
 

AtlWrk

Member
Dec 6, 2011
674
Have you ruled a few of the basics?
I would strongly suspect a physical problem (failing clutch, chafed wiring, loose/corroded connector, etc.) before a software bug.
Besides the clutches themselves, the harnesses are known to be problematic. Have you tried jumping the clutch to make sure it is capable of fully engaging? Remove the clutch connector and make sure the fan releases (it will continue to spin due to residual friction but you should be able to stop it with a rag at idle).

Later model years were programmed to engage the clutch more at startup when the A/C is on to boost cabin cooling. Once you thoroughly rule out a wiring issue I would start looking at a misbehaving clutch :-/ I get that the specific circumstances that trigger the DTC seem unique but it very well may just be that your clutch is borderline--the command to engage at startup due to A/C is just enough to push it to set the DTC. :twocents:
 

KNBlazer

Member
Feb 8, 2012
811
Somebody have the website to check the latest CAL ids.... there might be a patch for this, especially since it looks like it's only an SES light....
 

triz

Member
Apr 22, 2013
746
Fan clutch most likely. Could be failing.
 

bobdec

Original poster
Member
Apr 19, 2013
233
OK, did a tis search on my vin. There's 1 CVN for DTC P0483 listed under the OS and 2 listed under the engine diagnostics, so GM has been playing with it.

As an update. DTC came on yesterday after sitting all night and 20 seconds after starting with the A/C on. Playing with it today w/SES indicator on (DTC not cleared) I found I can NOT stop the fan (with a leather glove on) at cool idle. Cleared the DTC and could then stop the fan at cool idle as normal. That verifies the PCM is commanding clutch on after the DTC occurs as stated in the mode 6 diagnostics.. As a reminder this thing ran 5 months w/o a DTC nor any cooling issues during the 5 months when AC was not used.

I think my options are 1:smile: bring it in and pay a dealer to see if I have the code updates or not, if not apply the updates (?? $$) . 2:smile: Shotgun and change the clutch ($130.00) even though I can't see anything abnormal. 3:smile: Send PCM to PCM of NC and get DTC tuned out and get a performance tune as a benefit for $160.00. 4:smile: Buy HP Tuners, block the DTC and do the tuning myself (I have tuning back ground) for $500.00. Got to think about it..
 

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