You aren't reading your own exhibit carefully enough. The text for the chart C12B says at the second bullet, "Battery voltage is supplied to the fan relay on terminal E and ignition voltage to terminal C." Terminal E is circuit #902 on the main fan relay and circuit #903 for on the auxiliary fan relay. They are what powers the fan motors. Terminal C ("ignition voltage")is circuit #351 for both relays. If ckt #351 were the ground and the trigger for the fans, as you suggest("#351 runs to the ECM from the AUX fan relay"), both fans would operate in unison, perpetually, because they are the same circuit. Unfortunately from the partial schematics provided, it is not possible to trace ckt #351 beyond one side of the 29 point connector, #12015509. The same is true of ckt #936, the ground that triggers the main fan. Fortunately, ALL of circuit #335 is visible in the upper schematic view. Circuit #335 simply runs from terminal B on the auxiliary fan relay to the auxiliary fan switch (12015373), which grounds circuit #335, when the switch temperature closes the switch. NOTHING else connects to terminal B of the auxiliary fan relay, anywhere along circuit 335, or at the fan switch that could ground circuit #335 and run the auxiliary fan, such as from the A/C system OR the ECM. The auxiliary fan is controlled totally and solely by the fan switch. It is as clear as day, and right in front of your face!

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On my 86 I can simply change the auxiliary fan switch located on the drivers side head to come on at different temps. The main fan is controlled by the ECM. the aux. is not.

I think you can jumper a wire from the aux. fan switch to the main fan relay and make the main fan come on at the same temp. as the aux. fan.

 

Yes. Yes. And yes. However, as factory wired, per the supplied schematics, NO amount of programming will run the auxiliary fan. There is NO tie between the two.

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They would except there is another terminal 935 on the main fan circuit that the aux does not have which would prevent the main from coming on with the aux unless called for.

 

Wow,....it's always interesting to see what happens when great minds get together. First ...yes pete you did, thanks. ....yes it is my first computer corvette, and i am learning. The auz. fan was a option in 86, may have come standard on the Z-51, haven't checked.
I did check my last post from alvin and yes the fans will be taken care of in the reprogram. Thanks everybody for your help i really am impressed with the vast amount of knowledge on this web site, and the willingness of the members to share it. ...
Now if i may, ...has any one used that ecklers bias spring and if so what do you think of it? ...joe ...

 

What you quoted from me was in reaction to your having said that both fans were activated by circuit #351. Since that isn't the case we can move on. The power (positive side) comes into the relays primary (activating or trigger) circuit (circuit #351) of both relays at terminal "C". Circuit #935, at terminal "B", grounds the primary circuit for the main fan, which triggers the relay to close the power circuit #902 (and run the main fan). Circuit #335 is the counter part of circuit #935, but for the auxiliary fan. When the fan switch closes, circuit 335 is grounded, completing the primary circuit for the auxiliary fan, which triggers the relay to close the power circuit #903 (and run the auxiliary fan). Trace circuit #335 in your schematic (not the chart) and tell me where it could possibly ground, other than at the fan switch. Neither the A/C switches nor the ECM, or wires connected to either, come anywhere near the primary (control) circuit for the auxiliary fan. Believe your eyes, not the ramblings of so called "experts"

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Joe, the bias spring is worth $50 in my eyes. It is one of the few, cheap mods that gives seat of the pants results. Car stops much better. Most would agree with my opinion. It is easy to change and can alway be put back to stock, if you ever choose to.

 

Thanks Pete, I have to agree that for the money it's got to be one of the best deals around, and since i'll be changing pads and checking rotors this spring it only makes sence to give it a try, it's a easy enough thing to do, so i might as well add it to the spring tune up list.
I really do appreciate everybodys help, and while i have read a lot of the posts on this site,.... i didn't say i retained them! And as much as i hate to admit it, i just realized that over the last few years i haven't worked on the family cars, like some racers/ex racers, i developed blinders,....if it didn't have to do with the race car,...well i didn't have time to mess with it, take it to the guy on the corner, i mean thats what he's got that a.s.e. patch on his shirt for. ...Hmmmm, since i no longer have racing as a excuse, i guess i better sart paying attention. ...

 

Sorry I couldn't help you with your bias spring question. I have no experience with that. A couple of us got off on a bit of a tangent, but at least you now know that if you or someone before you hasn't messed with your fan wiring, a chip change cannot affect the operation of your auxiliary fan.

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Yes, but if you already have the switch, why do you need a chip to program the fans? Do some mods, then have Alvin burn you a chip.

 

In his initial post he was planning to return the switch, which I was trying to discourage, knowing that the reprogramming won't affect the auxiliary fan. I rethought that position, since he posted how cold that switch is set up for. The lower temps of the main fan will probably sufficient.

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Thanks again guys, as for future mods, i'm trying very hard not to go there, i have been down that road so many times that i have a path so deep that i have to look up to see day light! Yes i know that having a chip burned is a mod, but that is all it's going to get. This car is just for me to play with in the mountains, it will never go to the strip...ever.
I sure didn't mean to start that debate, however it is very refreshing to watch and learn about this car from people who have this much knowledge and passion about it, hopefully in the future i'll be able to do the same for someone else. Thanks... joe .. ...

 

Whether is is for modifications, repairs or checking on how things work, the factory service manual is one of the more valuable tools you can put into your toolbox. It simply cannot be beat for it's trouble shooting charts. If you plan to work on your own car, it can save you a TON of money.

RACE ON!!!

 

I have to agree cfi, it has to be the best thing a person could do to learn about this car. And i also have to admit that i bought this z-51 just to help me transtion from racing my altered, to just driving on the street again,.....boy was i wrong!.....Flying through the mountains in this car is more fun than i've had in years!!.....I only wish i had done it sooner!.....Thanks...joe...