I am having a heck of a time getting the Electric Cooling Fan to come on. I am not at all getting any power to the plug that goes into the motor that mounts to the radiator even when the temp is high. Currently I have it hot wired but would like it the way it is supposed to be.

I have already replace the below

Fan Relay (Under hood)
Temp Switch (on intake manifold next to radiator hose)
Temp Sensor on Exhaust manafold (not the O2 sensor)
All fuses in fuse box are good.

Is there a Fuse for the Electric Fan that is not on the General Fuse Block?

I have a Chiltons for 82-92 Camaro but I dont see hardley anything on the Electric Fan.

Please help any Ideas?

Many Thanks,

Chris

 

The fan switch is none of the above. It is in the passenger side cylinder head, between the 6 & 8 cylinders.

 

Sorry I forgot to list that. I did in fact replace that a while back.

However About the same time (after I think) I installed it. When checking and testing the temp it overheated (I forgot I had it running) and temp got up to about 250 or so before manualy kicking on the fan.

Could that have toasted my new switch?

Is there a way I can Test the Fan Switch?

And I get a Check Engine Flash Code of 15. Wich I read indicates:
Coolant temperature sensor signal indicates a temperature colder than -27? F for 30 seconds after the engine has been running for at least 30 seconds.

Many thanks,

Chris

 

I had the exact same problem and thats when i said screw it and decided to do a big block swap. but when i bought my car it was jacked up from the start so.. wish ya luck

 

Does the relay operate with voltage supplied directly? Take off plug and supply grd to one side of winding and touch 12 v to other. If this works, then ckt problem goes back to sensor to tell relay to kick in. Is this a model with one or two fans? Air on ought to turn always on.


If you feel like just giving up; then test sender by seeing what it supplies. When it detects temperature too high, what does it send? Or does it simply pass a ground or battery THROUGH a CONTACT (two wire sensors) If it sends battery, or, ground direct to relay like almost all aftermarkets do, then relay ought to operate. Whatever the sending unit sends, the relay would have to have the other polarity already sitting on other side of winding. (check your sending unit, and your book-electrical diagram) BUT IF IT DOES NOT, then there is a path open that is not operating. The same diagram will give you all this info. The wire or connector may be open to one side or the other. The fuse you are checking may not be for the correct application. Lots of temp senders in there. At least two, one for gauge and one for switch. Computer may have third of its own. These car years have changed so much in the 80's to 90's that i cant memorize the ckts. I need a book. When I type I try to cover all bases.

I just decided to edit this and add this. Did you somehow get two sending units wrong from the store? I wont mention their name, but I have a parts store here where I sent my son twice, my wife twice and finally ended up there myself to get the last RIGHT one for the temp gauge. NUTS????

 

You might be right. I came home with what I thoght was a coolant fan switch and he sold me a coolant temp switch.

His description above is like me right now. All fusible links good. Relay good. underdash fuses good. Getting power from the red wire(relay plug) getting power from the brown wire(relay plug juice comes from fuse box) but nothing from the green wire w/ white stripe. I can run a jumper wire from the red wire to the red/black wire and turn on the fan.

Tomorrow I am goin back for the coolant fan switch. Part # SW500 from autozone. I'll ask for the specific # so the goober don't give me the wrong one this time.

At first I though the guage must be wrong because it still ran fine w/ no missing or knocking. But once I turned it off, it puked about a gallon or so back into the resevoir. Thr great plus is I found a new little leak in my intake right above cyl #1. I'll try retorquing the intake to fix that.

 

Not the same outfit, but same problem. I get on the matching website and get their own number and then drive to the store on MANY items these days. Just to be sure. Sorry to hear about the intake leak. Ive had those silly things happen. If it were me I would remove intake and start over. Have an opinion on the torque numbers we are supposed to use, but wont mention my opinion cause I could cause you more problems. I do mine my own way these days and since I started, I dont have any more problems.

At least glue your gaskets to the intake and dont worry about them moving. Not the engine.

This is going to sound strange too, but I NEVER do anything to any part of a cooling system, not even changing a simple hose, without also cleaning radiator, flushing, and adding all fresh antifreeze with a fresh bottle of good old fashioned Barrs stop leak. I change my antifreeze twice a year so I dont get caught with the stop leak messing anything up. If you change only the radiator, you never get all of it out, so what I do is a simple safeguard to get it all.

Somehow, no matter how tight I get the one silly clamp, it seems to want to leak no matter what. ANY engine I have done ANY work like a manifold to, will always get an oil and filter change also before I will crank it. I want to know that the oil is clean before I crank it and will then know if the level is correct. Should I note funny color or raising of oil or lowering of oil level or coolant beyond any normal amount, I will know something MAY be amiss. I always add the last amount of coolant while engine is running and observe closely for any strange behavior such as bubbling or gurgling I wasnt expecting. This kind of observation is real helpfull if you know what to look for and the only way to get good at this is to DO IT.

 

I do pretty much the same maint except for the stop leak. This coolant system is all almost brand new from the previous owner because he couldn't keep it cool. He paid to have all new installed and the fan still wouldn't kick on to cool it down so he got mad and got rid of it.

Well I got a new coolant temp switch and changed that. It still didn't kick on the fan. So to test it one more time, I pulled the prong out of the plug and grounded it(since that is what the switch is supposed to do when it reaches the proper temp). It kicked the fan on perfectly. So I figured it was a bad switch. So I drained it and took it back to them. Went to Checkers to get theirs. I put that one in and warmed it up and still nothing. I'm aggrevated by now and am not going to let it kick my ***. So since power to the fan is switched at the ignition, I just grounded it permantly to the body. Yes the fan will stay on all the time even when it's cold, it's better that fooling with a toggle switch every time it hits 200. You have to remember, I have a wife and it only takes one time to forget to flip the switch.

So with it wired permantly on all the time, it stays between 200 and 220 all the time. I live in Vegas so the fan on all the time during the summer months will not hurt it. (better safe than sorry)

 

Am going to mention this just because? There are three types of sending units available. One would be the temp gauge, the second would be the warning lite, a much higher temp than the third, fan on switch. Now it may well be that the warning lite simply does not exist but I see it in my wiring diagrams and it ought to be available at the parts store for somebody to sell. The third is the ENGINE COOLANT TEMP SENSOR.

I have opened my Hanes manual to chapter ten. One being sold by mistake to turn on the fan is probably the coolant temp switch. Makes real good sense too, cause the name implies the job??????????????? You do not want one of these cause in the Hanes book it is wired to an INDICATOR, lite bulb, not gauge. A warning indicator that comes ON at a HIGH reading, like 260 or so. Not wired to Fan ckt. Could be HANES is wrong??

I find these two in the instrument wiring section-page. The right one is called ENGINE COOLANT TEMP SENSOR. (Not shouting) It feeds into the ECM, where the brain decides what to do with it. I suspect that a wrong sender will give a trouble code. I also suspect the the ECM can go bad in this ckt alone and actually might have to be replaced for this trouble sometimes.

Bypassing will make the fan run, should cause more trouble codes. As a better fix I would check output of sender and if that ground came on like it should, then the ECM has a problem or the path from the ECM to the Fan has a problem. Yes the best fix may be an ecm, but another and even better one even with a good working system, is to run an extra wire from this sending unit to operate a new relay that you install. Easy enough to do. Wires just like factory relay? But is straight to sender rather than through ecm. Might be worthwhile to test relay straight to sender when that ground shows up and you'll save buying a relay if it works. Path to and from ecm can easily be checked with digital voltmeter and a good sized needle, safety pin, to punch into wire. I would not use test light. A test lite passes its electrical source like battery or ground back to the ckt you are testing and therefore may damage an ECM.

 

I have edited this post to mention that I was looking at MY car, an 86. Your 88 would wire differently and i would look at the Haynes for yours. They changed in 87. BUT all this does mean that a part store clerk may have even more parts choises than just three. If they have different names in 87 up then things get even more interesting.


Should have included the wire colors.

Yellow and Black, black is grd. For the one going to the ecm. Coolant temp switch going to tep indicator in dash (light bulb) is grounded on engine and has dark green going from it, to dash, direct. Coolant temp switch has ground also onone side directly from engine and one wire going out which also shows as dark green I am under the impression that the two, both the lite and the gauge do not exist at the same time on the car. Its one or the other (I believe). But the problem is that the parts store will hand you the wrong part.

So what I just indicated according to my Haynes book, is that a two wire switch is the right one for the ecm and a single wire is used for either gauge or lite. This makes me wonder about a lot of things, but I didnt have a proble after I got the gauge working cause I installed my own fan relay and sender directly to it. Not through ecm, dont use the ecm for anything anymore.I have edited this post to mention that I was looking at MY car, an 86. Your 88 would wire differently and i would look at the Haynes for yours. They changed in 87. BUT all this does mean that a part store clerk may have even more parts choises than just three. If they have different names in 87 up then things get even more interesting.

 

I see what you are saying, but mine is a 91 RS.

You are probly correct in saying to baypass the ECM. Since mine doesn't go through the ECM the next logical step would be to bypass the wiring harness and loom and wire directly to the relay and see if it would kick itself on like that. I didn'nt think of it that way, but if the switch is working, then the rest of the system would work. But I went for the easy shortcut and just grounded it directly to ensure it's operation. It's a cheap shortcut that I will probly reconfigure, but I just wanted insurance of it's operation now and I'll try the direct wire to the relay next to see if it works then. Thank you for your advise and guidance.

 

Yeah, even at Chevy they realized that making the ecm do important functions like temp control might force us to change a computer just to trace a problem down, not good.

I dont get the "Coolant fan switch" terminology after the other terms used before. In both cases the dark green white wire is the one that counts. In the early model it comes from the power train control module and in yours directly from the switch. Which I presume is the thing screwed into the block or manifold, with ground as its basic supply.

I just gave MINE as an example of how messed up the man working and the counter person at the store can get. In my case I added a bonus, I asked someone else to pick up the part TWICE over. Only one I wanted was one for gauge. Ended up with right one eventually, but had installed the ecm sender already so I bit the bullit on the price. My ecm isnt used for anything though I havent removed it, most of the wires have been traced back and cut off. Mine is not a "switch"; its a sensor cause it goes to the puter

As I mentioned. A simple painless wiring product in the form of a sender/switch for about 185 degrees or so and even with the factory relay, everything works all by itself. ( a complete kit is available) Even for folks that wish for their ecm to know the temperature and own models like mine, this could work out with BOTH units installed, giving us FOUR (4) different temperature information sending devices. Are there that many holes to stick them in?

Not only that, with many of these senders only having one terminal and being wired to green and white green wires, the whole thing gets so strange. A warning lite will go on at 260 or more, if same one is used to operate relay, this can be fun. If a gauge version sender is used the relay wont work at all.

Another plus for confusion is the places these senders go into. I have read a lot of these posts for camaros as well as other chevies and there are about as many opinions as to where they actually are supposed to be in the engine, as there are posters. I have never seen a diagram made by anyone in the aftermarket business that showed the correct location for these senders for various years.

Might be located on the label in the engine compartment, but I have never been able to read one of those yet. All the cars I have seen recently are too old and beat up to read the label.

Just seems that Chevy used to standardize REAL well and doesnt anymore.

 

i have that haynes book, i can scan the pages for you and send them to ur email.....let me know, i got this vacuum line diagram and i might need help deciphering it if someone has the time.