Hi everyone, well I just got my car back from the autobody repainted etc. Ok so I reinstalled my fans and the whole nine. I had originally removed all that stuff to make the painting of the car easier for the painters.

well now my primary fan does not come on when the car gets hot. My Heavy duty cooling fan does kick on at 240 like is suppose to but the primary does not kick on at all. Here is the kick though so today I was like let me plug in my scan tool into the car just to see if anything comes up (no service engine light was on) so i plug it in and turn the key to run and what do I hear the primary fan starts up. I was like well that rules out the fan not working.

I am assuming (ooo the danger in that) the scan tool tool grounds something as would the ecm when the engine is hot and it recieves the signal from the cooling temp sensor located in the front of the block.

Now I know what you are thinking its the sensor at the front of the block. well I changed that sensor about 8 months ago before I had a minor collision with the front end. So I don't think the sensor is going to go bad on me that quick. Any suggestions out there?

 

You know I have read over and over that people have this problem with the fans but yet no one ever follows up with what the solution was...I keep reading to wire in a manual switch but thats just a bandage u know what I mean? so here I am bumping the topic hoping someone can spark something

 

You emailed me, but I now see your thread. Not being a 3rd gen person, I passed it by.

My email response was this:

I am at a disadvantage, not knowing exactly how the fan circuitry is arranged on the 1992. If it is similar to the 4th gen, it might seem that the computer is may not be sending the command to turn the primary fan on (as you have proved that the fan actually works when the DLC pins are shorted).

I would suggest watching with a scanner as the temp reaches the ON temp for the primary fan and seeing if it commands it on. If the scanner says the fan should be on, you would then have to electrically check the wiring for the proper potentials (if the fan did not come on). Again, I don't know how the system is put together, so I really can't tell you more specifics.

 

Hi shoebox, thanks for the reply im actually trying to get my scanner to work here so i can scan in the schema.

 

Ok everyone here are all the new scans this should really help out some people out there

If anyone knows where I can host these on a camaro site let me know.

General Overview of Fans


Chart C-12 - Fan Schematics Overview 1of2


Chart C-12 - Fan Trouble Shooting Chart 1of2


Chart C-12 - Fan Schematics Overview 2of2


Chart C-12 - Fan Trouble Shooting Chart 2of2


Fan Relay 1 Overview


Fan Relay 2 Overview (Heavy Duty Fan Relay)


Ok so there it is dam that took some time btu def hope it helps others out there!

 

Ok people did some more testing today.

First off I decided to test a few theories out. I have a 1991 z28 so I decided to test on her to see if certain things were the same.

Ok so the 1991 z28 the original owner hardwired the secondary fan to constantly be turned on. My next test was to see if putting my ALDL (Assembly Line Diagnostic Link) tool into the port would cause the primary fan to come on when checking for engine codes. Guess what it did. So placing the scan tool in the port and turning the key to run (Not engine on) will energize the primary fan motor. Same situation that happened in my 1992 z28.

Now what I did was disconnect both fan relays (the ones located by drivers side of the firewall) Then I placed my scan tool again into the port and put the key into run position. Both fans again turned on. So and correct me if I am wrong - I assume that the fan relays are being by-passed when the car is being checked for codes via the ALDL and that the fan relay is also by-passed when it is hard wired (thats the obivious one

Ok so any thoughts on how I can test to see if the relay is malfunctioning? I also swapped the relay but of course if chking the car for codes by-passes the relay then I still have not proved that the relay is working.

Also what are the chances that the relay has gone bad? I was thinking perhaps I should grab the old temp sensor that goes in the front of the car plug it in (Not into the engine just free floating and hit it with a propane torch heat it up and see if that turns on the fan lol...Of course this is just a theory not sure if it will work