Cooling fans puzzle
 

Guys,
I noticed my radiator cooling fans (i.e. the two fans: upstream/downstream from radiator) are not working, not even above 230F. If I leave the engine on, it will fry eventually.

What I did was the following: I removed the cooling fan relay (next to the brake cylinder). With the key on, I jumped the red/black and red wires, and nothing happened. I also looked at the CFan fuse, and it seems to be OK. From this, one may think i) I don't have power in those wires (how can that be if the fuse is ok?), and ii) the fan motors are gone (how is it possible that both of them went bad at the same time?).

What do you think?

thanks

BTW this is a 86' Corvette.

The fuse is for the primary side(coil), power for fan comes direct from battery via 2 fusible links. Follow the red back to the orange fusible links.

From my 86 FSM

http://members.shaw.ca/corvette86/Co...%20Control.pdf

Fuse is only for control side of relay;
Inline fusible links supply the power actually going to the fan motor
check fusible links and connections

Hey thanks.
Wait. Could you please elaborate a bit more? I think you are trying to say that the fuse is only along the coil of the relay but it is not along the main power supply line?. Would you please tell me where are the fuses of the main power line located then?

I did :D

Each fan is protected by an inline fusible link.

OK, I'll try to find them. Just a last question: are both fans controlled by the same relay? (i.e. should they turn on at the same time by the same signal?)

thanks!

Operate independently at different engine temps
Main fan from computer (228F );
Aux fan from it's on own standalone mech switch (238F ) in the head

Thanks!
I went down to the garage but I haven't been able to locate the fusible links. I see things down there along the wire to the positive battery terminal but I'm not sure which ones are the ones I'm looking for (Link E and D).

However, if you see the pics in this other thread:
http://forums.corvetteforum.com/c4-g...questions.html
I've seen something surprising and is that I have the orange wire that links the fusible link with the metri-pack but I don't have the orange-black part linking both, it just has disappeared. Is this related to my problem?

Unsure what setup '86 had but in '85 the main power cables ( with fusible links ) came from the starter Pos terminal

In '87, all power wires ( with fusible links) came from a termination block mounted on firewall behind the battery with a heavy wire linking the block to the battery Pos
Black cyl shown in pics is the fusible link

Which fusible link is it? Because there should be more than one. How do I identify the one of the cooling fans?

OK, now that I am not typing on my phone, I'll go into better detail.
The 2 orange links for fans are between main fan relay and positive battery cable. Two red wires come from battery cable(at terminal), they travel a couple of inches and connect to fusible links. There is a connector after links, which plugs into 2 red wires, one for each fan. That connector is just below and aft of main fan relay, just below the brake booster.

Is there any reason why the two fusible links (for main fan and for aux fan) should go bad at the same time??? Thanks for the info, I'm going down now to try to find them.

Sharing some more data.
Let me reedit this:
-Took voltmeter between terminal B of the relay harness and negative battery terminal, gives 0.16V. I guess that's OK because it means the ECM is controlling terminal B and terminal B is energized.
-Took voltmeter between terminal E of the relay harness and positive battery terminal, gives -0.03V. I guess there must be a resistance associated with the links and that is why you have a voltage drop from the positive terminal and the relay harness terminal E.
-Took voltmeter between terminal E of the relay harness and negative battery terminal, gives 0.25V.
-Took voltmeter between battery terminals and it gives me 12.5V.

The conclusion is that my car does not satisfy the Maxwell equations, WTF????. How is it possible I only have 0.25V between E and the negative battery terminal???

Also, I tried to ground E by connecting it to A, but even with the engine running the fan does not come on.

Help!!!

Could anyone please tell me if these are the fuses for the fans:

http://i63.photobucket.com/albums/h1...isc/wiring.jpg

and how the hell those four cross wires work? It happens I don't have the wire on the right upper part of the X (the dark blue one), it seems it has been cut by some a...ss

Thanks a lot.

did you pull the wire off the pass side temp sensor and jumper the wire to ground with ignition on?

Do you mean grounding terminal B of the relay harness?

The circuit diagram shows two seperate fuses

He is talking about putting the connector to the temp gauge sender on pass side head to ground
or he is confused and means the Aux fan switch which is in the drv side head on your year

unplug the wire at the temp sensor and ground the wire. you didn't say earlier if you had started there or not. That way you know the temp sensor is good. sensors are probably ok, but if you trace down a problem farther down the line but the sensor is bad you you still won't have the fans come on. Might as well take the 30 seconds to check it while you are already on the hunt in that system :thumbs:

The temperature switch on the driver's side head between spark plugs #1 and #3 controls the auxiliary fan in front of the radiator. You can test the fan by unplugging the connector from the temperature switch and shorting it to ground (I used a bolt on the alternator). The auxiliary fan should come on when you do this.

The main fan behind the radiator is controlled by the ECM. You can make it come on by shorting terminals A & B together on the ALDL connector.

Fusible links look like wires because they ARE wires. They have a smaller gauge than the wires they are protecting. The idea is that the fusible link melts instead of burning up the main wiring. The black cylinder in the linked picture is a SPLICE that has plastic molded over it to insulate it. I think the connector on the left is the ECM reset connector. I don't know what the connector on the right goes to. On my car the wire with circular lug goes directly into the battery terminal. Maybe it's an aftermarket replacement.

In my case I bought two positive battery cables because the first one I ordered didn't look correct. The second one was exactly the same. Problems I had with this cable: Everything on this cable was black (the original one was red). The plastic on the part that bolts to the battery is black, the wire that goes to the starter is black, the wire that goes to the junction block behind the battery is black, the hole in the terminal that goes on the starter stud was too small and I had to open it up with a file. I had to cut off the original ECM reset connector and splice it onto the new cable.

The cables I saw on the Eckler's web site don't look like the stock cable. Here's the basic cable:

http://www.ecklerscorvette.com/corve...1986-1991.html

Apparently you're supposed to buy this part:

http://www.ecklerscorvette.com/corve...1986-1987.html

and splice it onto the main cable. It appears to be the ECM reset connector.

I'm usually afraid of grounding wires connected directly to the ECM, I just don't want to fry the ECM. That is why I shorted A&E for the main fan, but nothing came out. Shorting A&B wouldn't add anything new, would it? Look also at my voltage measurements, there is something going on between A,E and the +/- terminals of my battery that I can't explain.

Grounding the temperature sensor is different, because it is not connected to the ECM, I'll do it as soon as I can and I'll let you know, good idea!.

OK, so the black thing is NOT a fusible link. My believe is that both the orange and the dark wires in the picture are fusible links. In the X that I have in my car, I don't have the upper right wire of the X, it can't just have been burnt and fallen, because it seems the PO cut it before, so probably one branch of the X is not active. The orange part seems to be in good shape (at least viewed from outside).