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Old 02-12-2017, 03:52 PM   #1
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Cooling Fans Constantly On

Hi guy's, well I thought my coolant temp sensor on the wp was bad giving me an ses light and continually running my cooling fans so I changed it, that wasn't the case if somebody can read a data log I did it would be greatly appreciated. It feels like the car is in some kind of limp mode, at the end of the scan it say's DTC fail. This is really frustrating.
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File Type: csv DLOG-2017Feb12-163258-2G2FV22P1R2248212.csv (659.2 KB, 29 views)

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Old 02-16-2017, 04:11 PM   #2
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Re: Cooling Fans Constantly On

Well you can always install an override switch.
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Old 02-16-2017, 08:54 PM   #3
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Re: Cooling Fans Constantly On

Your MAF sensor is reading extremely high and way out of range. The only trouble code for the MAF sensor on a 94 isn't much help here and apparently isn't failing now. Unplug it. If the engine runs better, it is defective. Unplugging it will almost certainly set DTC 48 and that may keep the fans still running.

What exactly do you mean by "...at the end of the scan it say's DTC fail"? What "says" that? Do you see any error messages when you start the program? Have you extracted all files from the zip file that scan9495 came in?

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Old 02-17-2017, 04:48 AM   #4
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Re: Cooling Fans Constantly On

Thanks Gary for your reply, what I meant about DTC fail was scroll to the end of my attached Excel file in my opening thread and see that it say's DTC fail, your program is fine. As for the MAF, I just replaced it in March of '16 with a Standard brand unit, I don't think it would turn the fans on to run constantly, I may be wrong though. I do get a bunch of electrical faults by your program. I will attach what your program found.
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Old 02-17-2017, 07:37 AM   #5
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Re: Cooling Fans Constantly On

The "DTC Fail" column is always in the log file. In your file it is empty of any codes.

If that screen you attached is during a scan, there are no current electrical faults, otherwise they would be highlighted in green.

Typical readings of the MAF at idle should be under 20. Yours is stuck at 470.
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Old 02-17-2017, 10:32 AM   #6
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Re: Cooling Fans Constantly On

470 grams/sec typically indicates the MAF sensor is disconnected, does not have 12 volt power, or has totally failed. Should set a code DTC 48. I don't have an MAF connected to my stock PCM, and my Scanmaster indicates '470.xx', and DTC 48 is set.

Somewhere previously you expressed concern the Fan #1 was 'lo relay' and Fan #2 is 'hi relay', questioning if that means something is wrong with fan #1. Those indicate that one relay is for the low temp (1994) fan (or both on low speed in 1995), and the other relay is for the high temp or high speed fan. The '1' in the column simply confirms that the PCM has commanded both the fans on.
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Old 02-18-2017, 11:05 AM   #7
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Re: Cooling Fans Constantly On

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Originally Posted by Injuneer View Post
470 grams/sec typically indicates the MAF sensor is disconnected, does not have 12 volt power, or has totally failed. Should set a code DTC 48. I don't have an MAF connected to my stock PCM, and my Scanmaster indicates '470.xx', and DTC 48 is set.

Somewhere previously you expressed concern the Fan #1 was 'lo relay' and Fan #2 is 'hi relay', questioning if that means something is wrong with fan #1. Those indicate that one relay is for the low temp (1994) fan (or both on low speed in 1995), and the other relay is for the high temp or high speed fan. The '1' in the column simply confirms that the PCM has commanded both the fans on.
Well the MAF is connected and I did a scan and got a code 48, now I just replaced the MAF a year ago yesterday so I have until 3-17-16 to replace it, it's a Standard unit which didn't last too long it's intermittent so I believe it's starting to go south. I'm going to get a credit for the Standard unit and I'm going to go with a Delco unit for a little more, thanks for your replies to this issue.
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Old 02-18-2017, 12:08 PM   #8
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Re: Cooling Fans Constantly On

Check the pink wire in the MAF sensor harness to insure you have 12 volts (key on/engine off/connector off the MAF). Check first by measuring between the pink wire and the black/white wire. That will insure the black/white ground and the pink 12 volt wire are good. If no 12 volts doing it that way, measure between the pink wire in the connector and a good chassis ground. That will tell you whether the problem is the pink wire or the black/white wire.

While you have the connector off, check for damaged or corroded pins in the connector and the MAF.

The 96 cars are notorious for the pink wire breaking somewhere in the harness bundle. Maybe 97's are developing the same problem.

If you have a multi-meter with a frequency (hertz) scale, put the connector on the sensor, measure the frequency between the yellow wire and the black/white wire. Should be around 2,500 Hz at idle.
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Old 02-20-2017, 04:50 AM   #9
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Re: Cooling Fans Constantly On

Well I did what Fred said to do, key to the on position and with a volt meter on the pink and black/white wire I got a volt reading of 12.36 volts so I know the connector is good, no brakes in the connector or the harness and the pins in the connector and MAF look good. Coupled with the 48 code and the 470 gps on the scan, I'm thinking the MAF is starting to go south. Thanks guy's for your input towards this issue, I would be lost if this forum wasn't available.

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Old 02-20-2017, 04:41 PM   #10
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Re: Cooling Fans Constantly On

Well what a big difference a new Delco MAF sensor made, check out my MAF gps now, I definitely need a good dyno tune to get her running up to par, my LT trims are way off. Please feel free to add if anything else needs to be addressed. Thanks, Scott
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Old 03-30-2017, 03:38 PM   #11
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Re: Cooling Fans Constantly On

Did the MAF fix the cooling fans?? If so, can you school me on how that would help? My dads '95 cooling fans are on at all times, except when the brakes are applied or in reverse.
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Old 06-14-2017, 06:58 AM   #12
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Re: Cooling Fans Constantly On

yeah im having the same problem....fan turns on at key turn....also my car wont start, but the fan thing is really bugging me.....your response would be great...thx
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Old 06-14-2017, 10:07 AM   #13
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Re: Cooling Fans Constantly On

Scan the PCM for codes. When some codes are set, the PCM responds by turning on the fans full-time. You need to provide basic info, like the year and engine in your car. Yes we see "Z28” in your screen name, but that needs to be confirmed. You really need to add a "signature".

https://www.camaroz28.com/forums/lt1...nature-879835/

Describe what you mean by "won't start". Does the starter engage when you turn the key to "start"? Is the "SECURITY" light on? If the starter engages, does the engine attempt to fire? Does it make any difference if the engine is cold or hot?
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Old 06-19-2017, 02:32 PM   #14
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Re: Cooling Fans Constantly On

I received this as a PM, but suggested that it needs to be handled in a public thread. I am just too tight on time right now to handle these issues one-on-one.

Quote:
Originally Posted by rmanz28
hello its rob
finally figured out how to do a signature....anyway, if you review my posts you will see my issue....I tried getting the scan software to work with no luck, then was refferd to a code reader actron CP9185...it seemed to connect but returned no DLC codes...hmmm. I did have to replace the battery since it was not holding charge....that prob reset them, and now since I cant drive it they wont come up....anyway

heres what I know:

turn key, fans come on (cant here if fuel pump is priming)
engine turns fine, sometimes get a rumble like it wants to start.
I see spark using inline spark tester
I have 40psi at shrader valve
I tested FP using prime conn...I hear it
I hear FPR clicking when I turn key

also, when I did the prim test...the fans didn't come on?....strange

that's about all I can tell you, my mechanic has it now, prob gonna cost me a fortune.

im just trying to learn as much as I can so I can work on it myself next time.....seems like all the threads that are close to my issue never tell what was wrong and how they fixed it......GRRRRRR

well thanks for reading

rob
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