Manual Fan Switch Installation
04-18-2008, 07:38 PM
#21
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Location: Orlando Florida
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I did it this way also about 4 years ago or so on my 94. I obviously connected to the secondary fans relay and used the dark blue wire #473 to close the relay. I never thought of getting a fan kit. I just used the parts that I usually have at home.
FYI – When the switch closed and the relay is energized, the PCM sees this as a fault since its not expecting to see a short at that point at that time since it did not tell it to close the relay. So it will throw a code (can’t remember I think 78?) that will always be stored in the PCM. Will not affect anything and no indication (SES) that it is stored.
Respectfully disagree with much of this. My cooling system works exactly right as it was designed with no abnormal problems. Here in Orlando where its hot most of the time, and hotter in the summer, the primary cooling fan just does not pull enough air in to keep things cool when standing in traffic. My A/C runs 99% of the time, even in the winter to keep the moisture off the inside of the windshield.
The duty cycle of the secondary fan is much less than the primary which runs all the time when the A/C is on. I only turn on the secondary fan when I get over about 210* or if it looks like I will be stuck for a while in traffic. The usage of the secondary fan is quite low and is probably no more than if it came on itself, but I am just doing it at a lower temperature. Secondary fans are not burning up.
Once I get rolling I can shut all fans off and come down to 195*. With only one fan running its doing the best it can in Orlando, which is not good enough when hot in traffic. With the second fan running the cooling is extraordinary better. There is no problem, things are working as designed.
As designed – opinion. The radiators are under designed for the car. I changed mine from a stock 7/8’“ GM to a new stock 1 ¼” GM. Made a nice difference. Larger radiators will help even more
Charge on
FYI – When the switch closed and the relay is energized, the PCM sees this as a fault since its not expecting to see a short at that point at that time since it did not tell it to close the relay. So it will throw a code (can’t remember I think 78?) that will always be stored in the PCM. Will not affect anything and no indication (SES) that it is stored.
Respectfully disagree with much of this. My cooling system works exactly right as it was designed with no abnormal problems. Here in Orlando where its hot most of the time, and hotter in the summer, the primary cooling fan just does not pull enough air in to keep things cool when standing in traffic. My A/C runs 99% of the time, even in the winter to keep the moisture off the inside of the windshield.
The duty cycle of the secondary fan is much less than the primary which runs all the time when the A/C is on. I only turn on the secondary fan when I get over about 210* or if it looks like I will be stuck for a while in traffic. The usage of the secondary fan is quite low and is probably no more than if it came on itself, but I am just doing it at a lower temperature. Secondary fans are not burning up.
Once I get rolling I can shut all fans off and come down to 195*. With only one fan running its doing the best it can in Orlando, which is not good enough when hot in traffic. With the second fan running the cooling is extraordinary better. There is no problem, things are working as designed.
As designed – opinion. The radiators are under designed for the car. I changed mine from a stock 7/8’“ GM to a new stock 1 ¼” GM. Made a nice difference. Larger radiators will help even more
Charge on
Were did you put the second wire off the switch to get a good ground?
After you get the code (78) does the code turn off when the switch is open to stop the fan?
In the Mid-America's kit instructions it has 94-95 will get this code. I have a 93 will I not get this code?
Thanks!
Last edited by MY93TOY; 04-18-2008 at 07:52 PM.
04-18-2008, 08:06 PM
#22
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Were did you put the second wire off the switch to get a good ground?
Now all I have to do is get the 80 L-82 finished so I can sell it! Sweet car, just don't need it any more.
Thansk to all who offered their help!
04-18-2008, 08:47 PM
#23
Le Mans Master
Were did you put the second wire off the switch to get a good ground?
After you get the code (78) does the code turn off when the switch is open to stop the fan?
In the Mid-America's kit instructions it has 94-95 will get this code. I have a 93 will I not get this code?
Thanks!
After you get the code (78) does the code turn off when the switch is open to stop the fan?
In the Mid-America's kit instructions it has 94-95 will get this code. I have a 93 will I not get this code?
Thanks!
http://www.corvettedoctor.com/1992_93_DTC_Codes.html
FYI - The 78 error code that is set in the 94 does not light the service engine light. You would never know the code was set unless you checked for it. Once the code is set it will stay in there. I think you need a 100 ignition cycles for it to clear itself, but who cares. Does not affect anything.
The place I used for a ground was just forward of the relays there is a ground lug near the horn. I used that bolt. I used a double wire in a single jacket and ran it inside to car. I did not want to cut anything up, so I mounted the switch below my seat on the track pipe.
04-18-2008, 09:33 PM
#24
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I do not believe that you will get that code because I don’t believe that code exists in the ECM firmware. The PCM is a much different kind of unit (different DTCs) doing the same basics but a bit more elaborate. Check this link, I don’t see the error code for the 93.
http://www.corvettedoctor.com/1992_93_DTC_Codes.html
FYI - The 78 error code that is set in the 94 does not light the service engine light. You would never know the code was set unless you checked for it. Once the code is set it will stay in there. I think you need a 100 ignition cycles for it to clear itself, but who cares. Does not affect anything.
The place I used for a ground was just forward of the relays there is a ground lug near the horn. I used that bolt. I used a double wire in a single jacket and ran it inside to car. I did not want to cut anything up, so I mounted the switch below my seat on the track pipe.
http://www.corvettedoctor.com/1992_93_DTC_Codes.html
FYI - The 78 error code that is set in the 94 does not light the service engine light. You would never know the code was set unless you checked for it. Once the code is set it will stay in there. I think you need a 100 ignition cycles for it to clear itself, but who cares. Does not affect anything.
The place I used for a ground was just forward of the relays there is a ground lug near the horn. I used that bolt. I used a double wire in a single jacket and ran it inside to car. I did not want to cut anything up, so I mounted the switch below my seat on the track pipe.
Thanks for you quick reply!
I'm like you I don’t want to cut anything up. I like where you put the
switch.
07-11-2019, 05:50 PM
#25
fan switch mod
Hi IceDazzlr,
I too have a 94 and same situation as you had. I am very interested in doing the switch, however i am not good at electric stuff and it scares me but im willing to try. Can you do me a solid please? A write up on how to do this for dummies (me) with pics, how too, simple instructions please. Im in cali and its hot here. Please help. Please send to my email pumasixtynine@gmail.com thank you.
I too have a 94 and same situation as you had. I am very interested in doing the switch, however i am not good at electric stuff and it scares me but im willing to try. Can you do me a solid please? A write up on how to do this for dummies (me) with pics, how too, simple instructions please. Im in cali and its hot here. Please help. Please send to my email pumasixtynine@gmail.com thank you.
06-01-2021, 11:07 PM
#26
Instead of running wires, I unplugged my A/C and pushed the A/C button on the dash with the motor running. The primary kicks on, but my A/C does not. Great hack if you don’t need A/C.
06-02-2021, 04:01 PM
#27
Melting Slicks
You can run the radiator fans by turning on the air conditioning. No wires, no mods, no work required. They come factory this way, and it cools down the engine quickly.
10-18-2021, 03:47 PM
#28
Advanced
Fan control switch.
I installed my own switch on my 87, it should be the same as a 94. Connect a wire from the fan relay ground wire (green/wh on an 87) and from the engine compartment snake it through the rubber boot in the door and into the passenger compartment. Connect the wire to one switch teminal and ground the other switch terminal. With the ignition on, when you turn on the switch, the fan will run.
