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Too cold! Need to undo dual fans constantly running
Well, it seems the previous owner wired the dual fans so they are always on. He probably did this because it was his summer car, but in this weather it is way too cold. I have printed out and looked over the dual fan wiring diagrams for my 88, but I am having trouble identifying how the wires in the connection to the engine harness are? Am I missing this in the diagrams or is there another diagram I can use? I see the black wires have been cut on either side, and I would like to replace those. And it looks like there is a ground wire spliced into a black wire for the fans, it is grounded above one of the fan relays. I don't see any modifications to the green wire so I am not sure how this is wired. :/ My goal is to change my wiring so the fans are not always on, but I don't think I want a toggle. I think I would like to wire it as stock but put in a lower temp fan switch. Any links, tips would be greatly appreciated. Thanks for reading. Black wire cut Both sides cut Ground splice to fans Grounded above fan relay Assuming this is stock?
Re: Too cold! Need to undo dual fans constantly running
You can get a new harness off ebay for about 70 bucks if so inclined. It goes from the fans to the relays and the main connector. Once you get the wires sorted you can use a fan switch (lower passenger side of head) for a mid 80's Buick regal/Gran National that come on about 200 and off at about 190. Works fine for me. Take a look at your diagram and see the AC circuit also runs the fans. I hooked my Buick switch into the AC circuit and both fans come off and on at same time. Cools quickly this way and doesn't stay on as long. Wired this way if my fan switch dies, the computer will still turns them on as they should from the factory at about 223 degrees. The green/white and the tan are the trigger wires if I remember right. If I had the diagram in front of me I could be more precise. The black being cut may be because the pin in the main connector fried. Pull it apart and look at it. Mine was fried I believe because it was wired to always be on when I got the car. I repined some of mine as needed. It's a pretty simple system once you wrap your head around it.
Re: Too cold! Need to undo dual fans constantly running
Originally Posted by Chopski
The black being cut may be because the pin in the main connector fried. Pull it apart and look at it. Mine was fried I believe because it was wired to always be on when I got the car. I repined some of mine as needed. It's a pretty simple system once you wrap your head around it.
Ok, cool, thanks! I'm going to do some more digging thru the wiring right now. I'll open that up and take a look. I guess my only question would be what the black wire was for. I looked at the ebay pic and figured on the side side with the ORN, TAN, BLK/PNK, GRN/WHT, BLK the black is for the fan ground; but on the side with ORN, TAN/WHT, BLK/PNK, GRY, BLK the black should connect where originally?
Re: Too cold! Need to undo dual fans constantly running
Sure enough, I opened up that connector and the black wire was fried.
Gave the wiring a thorough look over and I cannot find any other changes to the wiring.
So I think what I'll do next is figure out how to test all the temperature switches and ecu connections. Maybe I was wrong to think he wired the fans to be on, something may be faulty.
I unplugged the relays one at a time and each turned off their respective fan. Unplugged the ac switch and fans stayed on. For tomorrow I'm leaving one relay unplugged and taped over to keep one fan off, at least.
Re: Too cold! Need to undo dual fans constantly running
If both fans come on the green/white is probably grounded as that one is from the pressure switch which will make them both run at same time. It's possible also that the secondary coolant fan relay wire is grounded which would make your car think it is very hot and go into panic mode and run both fans. I'm not sure how the logic of the ecu works but it would make sense. Like I said with mine I spliced into the green/white which tricks the ecu to think the AC switch is engaged which probably forces both to be on for max cooling. Dig through the loom and you will find one of the wires grounded but not likely the tan as it only controls the one fan. Somewhere he is using one pin (black wire) to fire both fans (meltdown coming) and if that is the case any of the signal wires grounded could make them both come on. Rip that crap apart and search. Remember the orange wires are the power supply to the relays and the black is power after the relays to each fan.
I really hate that people need to think they have to be on all the time. Its wasted power for absolutely no reason. Drags on the alternator and wears out the fans unnecessarily. It comes from the fact that the primary fan comes on too late with the stock set up and is unsettling. Put the Buick switch in and take it back to stock and it will work well. I like that both of my fans come on at once but it isn't really necessary most of the time. At some point I will correct it by reprogramming the prom when I start tuning.
Re: Too cold! Need to undo dual fans constantly running
Actually, the green wire with white stripe gets a ground signal from the fan switch and controls only the secondary fan. The ECM sends another ground signal on a separate green/
white wire to the primary fan relay that actuates the primary(driver side) fan. AC on also turns on the secondary fan. People often ground the green/white wire when the fan switch fails so that may have been done?? Who knows they may have also grounded that wire to the other fan relay. You're going to have to check the wiring and see what is different from the stock setup. People think up really strange
ways to wire things. Good luck with it, you can figure this out
Henry
Each relay should have four wires going to them. Big orange for power in, Big black with red stripe for power back to the fan, small tan or gray wire or some color like that for
12 volts with key on, and the grounding wire that actuates the relay
Re: Too cold! Need to undo dual fans constantly running
Hi, these guys are really sharp with fan issues, they will get you going. I am a rank amateur but I just had to get my 88 fans going and the only two small things I have to add is I would concentrate on the passenger side , or #2 fan first. This is because the drivers side or #1 fan should always run when the #2 fan is called to run by the A/C switch or the high temp switch or by an added ground wire. If you look at the diagram a signal is sent through terminal BD12 to the ECM which grounds the relay for the #1 fan. Soooo, if somebody has added a ground to the #2 fan and you remove it, that my fix the #1 fan running all the time,, if nothing else has been barfed with. If this has already been stated apologies. My 2nd tip is to take a look at Ebay for the electrical supplement to the service manual. I bought a shop worn copy for $10 delivered to the house,, indispensable! great trouble shooting charts. You just have to make sure you are looking at the correct information for your combination of components.
10-06-2018, 11:59 PM
