Well here's another new corvette owner with one of many questions I'm sure..I just got a manual fan switch for my 91 coupe. Directions for hook-up to fan relays says to attach one wire to each green and white striped on the relay. Well the secondary relay(the one on the right) has the g/w striped wire,but the primary(the one on the left) does not. So does anyboby have any ideas for this :confused:

 

I am only speaking from an 87-don't know if there the same.The primary relay is located in front of the battery on the wheel well-the auxillary relay is located next to radiator on drivers side. Someone on the forum tried hooking them up to the mass burn off relays behind the battery-where there are 2 relays side by side.HOPEFULLY someone with a 91 will chime in :thumbs:

 

According to my Hyanes the cooling fan relay control line colors are as follows:
Dk Grn/Wht - Primary fan
Dk Blu/Wht - Secondary fan

 

Hey, thanks for reply. For my 91 I know the relays are on the radiator shroud on the drivers side it's just getting the wire colors right. Thanks again.. :hurray:

 

When I look at the relays(their side by side) the one on the right has the dg/w and also has the dark blue and white. I saw the same thing in my Haynes manual for each relay,but this relay has them both..... :chevy

 

A guy on here called AGENT 86 helped me with this a few days ago..Both grn/wht and blu/wht go to terminal "f" on relays..grounding terminal f on either relay activates that relays fan..both relays are exactly the same..so if in doubt pull relay and look..terminals are lettered. I think the only reason for color dif is so you know where it goes from the other ends (at ecm ).
Good luck.

 

Why not let me burn you a chip to make the fans come on sooner with also the use of a lower temp thermostat? That way it works the way the engineers meant for it to work :)

 

Explain this burn a chip thing to me. How much and is it really that easy? I just purchased a kit to install but can't get the plug out of the side of the engine so I can install it. A simple chip sounds too good to be true. thanks for the info, Al :flag

 

I have a 1990. If you ground the blue/black wire on the 1st relay it will cause the fan to run. If you ground the DK Blue wire on the second relay it will cause the secondary fan to run. The Pink/Blk wire is a hot wire hooked to a 10 amp fuse going to your gauges. Definitely don't want to ground that! Al
:flag

 

The ECM commands the fans to come on by completing the ground circuit of the relay to ground. It does this by the ECT (engine coolant temperature) sensor input and as temperature rises it compares it to its fan turn on constant that is stored in the chip. When the coolant temperature rises above this setpoint it turns the fans on, once the coolant temperature falls below another setpoint the fans are turned off. Simple really it is. I just go in, change the constant to a lower temperature to work with a lower temperature rated thermostat.

Typical fan turn on temps for fan number one is 103*C and for fan number 2 is 113*C. That is the turn on temps for a stock 89 chip using a 195*F thermostat. 103*C = 217*F and 113*C = 235*F

For performance usage I recommend a 160 or 180*F rated stat. I change the turn on temps to between 85 and 89*C or 185*F or 192*F depending on which thermostat the person prefers.

 

Wow, didn't know you could burn a chip for a 91. Would also be interested in what the cost would be,etc. Sure beats trying to get this manual switch thing to work...Thanks

 

My jet chip turns fans on earlier than stock and if he can burn you one at a decent price it would be worth it. I however, would still consider the manual switch to give yourself total control in the event you have temp switch or ecm failure. There's really nothing to figure out..you simply buy some 10 guage wire and a switch and some little wire taps/splicers (small clips that neatly tie your wire into existing wire). Then you ground one end of wire to suitable ground and hook to switch then run wire from switch through firewall to engine compartment then tuck it into factory flex loom (wire harness to fan relays) and tap into terminals "F" on relays (discussed earlier) with wire tap splicers.It's best to tap in about 1/2 inch under relay so you dont get in the way of headlight movement.. You can do one fan or both by creating a "Y" with wire splicers then tapping into both "F" terminals. I went ahead and bought an inline fuse and put it on mine to be safe but I dont really think it's necessary on a gound..I just wanted to do it in case of any possible backfeed.

NOW, you are the ECM..you flip the switch and it grounds terminal "F" and fools relay into thinking they are recieving a command from ECM and VIOLA fans come on..It's really not rocket science..took me about an hour and a half and a six pack :cheers: And that included removing under dash panel on driverside and switch mount and wire running and ALL. I'm well pleased with the result. It's worth it. :thumbs:

 

skateparkdave-would prefer to use manual fan switch,but getting more confused by the minute....got this manual switch from Corvette Central,has a ground wire(with a screw) and 2 other wires for the fan relays. Now on top of each relay is a "switch diagram". Should I be splicing into whatever wire is coming from "f" on top of each relay? Because if I pull the wire harness out of the relay what I think I'm seeing is an empty space for F. This can't be as hard as I'm making it. :smash: :confused:

 

On my wiring diagrams the coolant fan "F" terminal is the one connectred to the ECM. When the ECM pulls this line to ground the fan turns on. Also the "D" terminal is connected to the C.FAN fuse.

Pick up a nice DMM at Radio Shack (this will be a useful tool later too), open the connector to the coolant fan relay and check the voltage on the wires to these two relay pins. With the ignition On you should see +12Vdc on the wire to pin "D" and probably zero volts on the wire to pin "F".

You need to connect the two wires from your switch to the wires going to the "F" pins. If the kit doesn't come with insulation displacement connectors (they just clamp around the wire), pick them up at Radio Shack along with mathing spade crimp connectors (these criimp onto the ends of your new wires and plug into the inuslation displacement connectors above).

Then the hook up is very simple as no soldering is needed. If you want a realy "stealth" job, bury the connectors and new wires inside a large wire harness alreay on the car.

Don't give up, it just seems difficult since it's a new area to get into.

 

Will give that a try. A DMM is a good idea,don't have one and looks like something that will pay for itself in no time. Thanks, Doug

 

TJ, sent you an IM on chip burn... thanks vinnie

 

ok, myblue91, heres the deal..you ground the ground and hook the other 2 leads to wires leaving terminal "F"...Pull your relay up to release it from mounting bracket then unplug relay and inside it the terminals are marked...dont use the diagram on top because it's misleading..
Here's what does what ..Terminal "E" is 12v hot always..is red wire that comes from a fuseable link down low behind battery. ..Terminal "F" wires are blu/blk or grn/blk its what gets grounded by ECM to activate relay and ground "F".. grounding "F" makes Terminal "A" Hot..Terminal "A" blk wire/red stripe goes to fan which is already indepently grounded so making this hot activates fan..Terminal "D" is pink/black wire that comes from ignition..so it's only hot when key is on..it's kind of like a "turn on wire" it makes the relay active only when key is on.so switch will not turn fans on when key is off..Terminal "C" is not used..I hope this clarifies it all for you..good luck :thumbs: Oh yeah..be careful when looking into relay for terminal letters that you dont get confused because when looking at it it's upside down and it's easy to get mixed up..look at it then hold it right side up and and make a note of where that terminal goes and what wire goes to it..or write it down..


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Will give this a try-skateparkdave-thanks

 

Could you please email me some info on how much you would charge me to burn a chip for a 1990 6 speed L98 coupe? I'm in the Navy and out to sea right now so if you could email me to wardf@monterey.navy.mil I am really interested in this and appreciate the help, Thanks, Al :flag

 

Ooops, I was at work yesterday and running on memory and wanted to clarify that on 90 ..on primary fan..wire to termial "F" is Blu/wht stripe and on secondary fan wire to termial "F" is light grn/blk stripe. Everything else I wrote still applies so as long as you just worried about terminals letters and not wire colors you should have come out ok..wire colors on 91 may be dif anyway but I know relays/functions are same.


[Modified by skateparkdave, 11:35 PM 5/25/2004]