RockInTheHill

Vehicle: 98 Civic Ex Vtec (D16Y8)

The cooling fan stopped working a few days ago. I replaced the fan switch sensor on thermostat housing, ECT sensor(sending), checked all fuses, relays are working properly, coolant is full and has been bled for air. The weird thing is, I jumped the fan directly to the battery from the plug that goes to the fan switch but the fan will only turn on when the key is in the off position. If I turn the key in the 'on' position or start the car, the fan will not run even though it is still jumped directly to battery!.
If I jump the fan directly atthe fan instead of the plug at the fan switch it runs regardless if car is on or off.
Just for a note, the car is not overheating when in operation. I don't know what else to do please HELP!

motegicivic

How long have you owned the car? Has this just started to happen.

What baffles me is jumping the fan and will only come on with the key off? and when you turn the key to the number 2 position the fan turns off?

Another thought.......I am wondering if the fan is not working (short in the fan itself) do you have access to another fan, I would plug it in and try to jump with the key on.

RockInTheHill

I just can't figure it out. Purchased the car about 2 weeks ago. Fan was working until a few days ago. Right now I have it jumped directly from the fan and it stays on while I'm driving but if I jump it from the switch connector it will only come on if the key is in the 'OFF' pos. I don't have another fan. I guess I will try it but I don't see how its the fan because its working. I also testing the voltage going to the fan switch sensor and its recieving 12v.

Anyone else have any ideas?

motegicivic

So basically it works when you are driving when it is jumped then, so at least you have a working fan, because you have it jumped at the fan itself, which leads me to believe there is a wiring problem between the fan switch and the fan itself, trace that wiring.

RockInTheHill

what is the best way to trace the wiring? Should I check for continuity between the connector at the fan switch and the connector at the fan itself?

motegicivic

I am thinking plug the fan back in and check for voltage at the fan switch plug (I assume key to number 2). You will prob need a shop manual and see the wiring diagrams, you might have a break in the wiring.

lazlong

Yes. Measure continuity on the same wire from connector to connector.

If no continuity you can
A) try tracing it down by moving ONE test lead down the wire closer to the other lead. You'll have to crack the wire harness open for this.
B) Just run a new wire and zip-tie it to the harness.

***NEVER check for continuity on a live circuit. (make sure both connectors are dis-connected)

RockInTheHill

Ok, I didn't trace any wires because I don't have time for it. I tested the voltage going to the fan switch with the ignition in "II" position and its receiving 12v. So there must be a break in the line going to the fan. I've decided I will just run a new wire from the fan switch connection to the fan. What is the best way to do this? Will I have to splice the positive wire going into fan switch connector and run a wire from there to the fan?

Thank you guys for all your help!

axis11

http://s3.amazonaws.com/2cp-images/q...jpg?1325818830

try this diagram. Running jumping wires is not a very good idea. Later on, the engine bay will be full of tangled wires. Fix the real problem.

motegicivic

I don't recommend it but if need be slice the 12 volt wire at the switch get some wire 16 ga at least, look at the loom and see if you can follow a path closest to the fan itself zip tie to that loom, or get some new loom to make it look neat.

dem0nk1d

you know what, i took out my a/c unit and the a/c loom that connects into the driver side wiring loom. i don't think my radiator fan turns on at the operating temp, i've also replaced the temp switch as well. strange, also my water temps are riding in the middle of the gauge due to over heating. oh well. i need to investigate my fan too. i've jumped the radiator thermo switch at the plug, to test if the radiator fan is good, which it is. i'm out of ideas.

motegicivic

Does your temp only go up when sitting? And you jumped the connector after the other wiring was taken out, so it def works?

dem0nk1d

yeah when jumping the 2P connector where the Radiator Thermo Sensor plugs into the fan starts, fine. I also know the a/c circuit doesn't have anything to do with the Cooling Fan Circuit.

i just got a rebuild kit for my d15, as i think i have a warped head. this is due to overheating in traffic.

motegicivic

That will cause overheating.

When you get a chance, run the car with cap off and look for excessive bubbling, also see if the overflow is filling up abnormally.