Okay, ever since I got my car, the fans have not worked. I doubt the relays are bad because I have switched them all around and the fans still don't come on. But if I pull the relay I can short it out and make them come on. I have the late model 94 system, which has the three relays for the fans. I am at a loss, the head temp sensor works, and I checked the resistance on the water pump temp sensor and it seems to be reading correctly. Could the PCM have been messed with? How would I reset i.

Shoebox, maybe you can help. I have read everything on your website and done every test you mentioned. And is I used a manual fan switch, how would that work when the car is off and I walk away? The car overheats about two seconds after I shut it off. Is there any way this could be happening by not bleeding the cooling system properly, or not mixing coolant 50/50?

 

Unplug connector C100 (this is the 10 way connector on the RH shock tower that has a drk grn wire in cavity J and a drk blu wire in cavity H. Something like
this .

Turn key ON. On the connector side going toward the front of the car (toward relay panel), use a jumper and ground the green wire in cavity J. You should get low speed fan operation from doing this. If you ground both J and H, you should get high speed operation. If you do, then the fans and relays are ok. You would then need to concentrate troubleshooting in the direction of the pcm.

The fans are wired like the schematic in the bottom of this.

On a 1994-1995 the fans will not stay on without the key ON.

You might even have a poor connection at C100.

 

Thanks shoebox, I am gonna check that tomorrow. As of now, I know the fans work, because we have jumped them or whatever, and I am pretty sure the relays work, because we have switched them, and I don;t see how four of them could be broke.

I have one more simple question though, should jumping the coolant #3 relay do anything, shoebox? I know the other two are the low and high speed or whatever, but the third one does nothing.

And how would I go about fixing the PCM if that is the problem? Is there a way to just reset it back to stock, because I am thinking maybe the moron that had the car before me set the fan temps at like 1000 degrees with a power programmer or something.

 

I think you should try your original plan first and reset the PCM. Just pop the PCM related fuses in the the fuse panel. Then go and start disconnecting stuff. Or atleast do this before you start doing all this other stuff so you can take it out of the equation.

 

Take it one step at a time. What did you do to "jump" the #3 relay? Both #2 and #3 provide high speed fans.

 

I wouldn't worry about someone raising the temps. It usually works in the other direction.

 

Yeah, but the guy was a moron, maybe he thought it would make the car faster. Shoe, to jump them, all I did was put a wire between 30 and 87. They are right across from each other on all of those relays I think. I know #1 was quiter than #2, or visa-versa, so I figured one was low and one was high. I will check what you said tomorrow, but how do I know which is J and which is H, or should I just go by the color?

I am just gonna do this stuff first, like shoebox said, becuase he is usually right. Actually, I don't think shoebox has ever been wrong

 

Oh, my bad shoebox, I thought you said #1 and #2 in your last post, not #3. I tried the same thing on #3, but nothing happened. Could this be the problem?

 

J is green and H is blue, as shown in the schematic and in the pic of the connector. The letter designations are embossed on the connector, too.

Jumping #3 by itself won't turn on anything. I guess you had the relay out and were jumpering between 1 and 4 on the fuse block (they go to 30 and 87 on the relay).

...and I can be wrong, just like the next guy.

 

With age comes wisdom...... or insanity and senility. Which is it for you Shoe?

 

Yeah, I should have cleared that up. I had the relay out and then jumped the two. This wiring stuff confuses the hell out of me, but I'm starting to understand it.

 

It must be stupidity. I hang out here all the time don't I?

 

lately I do too! I like helping people out when I can.

 

Hey shoebox, I did the test you mentioned above and it worked. So now I am at a loss, the WP sensor seems to work because I checked the ohms based on what your site says, and it was fine. Does this mean I should try resetting the computer.

Another thing I don't get is what the point of the fans running after the car is turned off. At idle, the coolant is still circulating, and therfore the fans will work. But with the engine off, after being run, the fans will only cool the coolant sitting in the radiator, leaving the coolant in the engine to be heated by the block, and then overheat. I'm sure I am missing something simple, so could someone explain it the right way? I just don't see how a car doesn't overheat when it is shut off, after warming up. Thanks

 

Good question, I've never really understood this either, my guess is that the thermo is at the hot coolant coming out of the block and "should" stay open even if very little is flowing past it because it's still hot from the block. The fact that the fans are cooling the rad shouldn't affect the thermo then.. just a guess tho? =o