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Alright, let's try this again.
I have a 94 civic d15b7.
When I got this car the previous owner had cut the connector for the radiator fan and ran a wire from the fan straight to the body for a ground, and a wire straight to the fuse box under the dash.
I never noticed it before because it was all tucked away. I let someone else drive it, and they somehow managed to pull it out of the fuse box, and I have no idea where it went.
I don't want to just plug it into a random slot and hope that something works and take the risk of messing something up even worse.
Any help is appreciated. Thanks.
Re: Radiator fan wire going to fuse box under dash
I've tried 4 times to upload pictures and it won't do it, so I'm going to try and describe it as best I can. There are 2 red wires (not stock wires) coming from the radiator plug on the radiator itself, one is thicker than the other. The thicker one is plugged into the positive terminal on the plug, and run through the firewall to the fuse box under the dash. The thin wire is ran through the headlight holes and grounded to the chassis.
The thick red wire coming through the firewall has come unplugged from the fuse box.
I don't personally have the knowledge to rewire the circuit, and I don't have time to take it to someone else to fix it before tomorrow when I leave for IA.
What I'm trying to figure out, is where can I plug the thick red wire into the fuse box under the dash to make the fan work again?
Re: Radiator fan wire going to fuse box under dash
Ok, so I put the wire where you said, and still nothing. So I ended up finding the wires to the original fan plug at the main harness and just traced it to the end, and I bought a new plug for the wires, wired it together, plugged it into the fan, and the fan still won't come on. I checked the fuse, and it was good. I shorted the ect sensor to test the relay and the fan still didn't turn on, so I bought a new relay, plugged it in, still didn't work. So I shorted the sensor again to test the new relay and once again, the fan still didn't come on.
Both upper and lower radiator hoses are getting hot, so the thermostat is working.
Do you think that replacing the ect sensor itself would correct the issue since I've already tested everything else?
Re: Radiator fan wire going to fuse box under dash
Fan relay is controlled by a thermo switch on the thermostat housing, where the lower hose connects to the engine. Jumping this switch should cause the relay to close and the fan to run as soon as the key is turned on.
The ECT sensor on the head and the ECU do not start the fan. AFAIK, the connection from the fan circuit to the ECU is only for monitoring purposes to estimate electrical load. If the thermo switch at the thermostat does not close, the fan will never start and the engine will overheat.
Look for burnt contacts in the underhood fuse box where the relay and fan fuse plug in. You may need to replace the box.
Re: Radiator fan wire going to fuse box under dash
Originally Posted by mk378
Fan relay is controlled by a thermo switch on the thermostat housing, where the lower hose connects to the engine. Jumping this switch should cause the relay to close and the fan to run as soon as the key is turned on.
The ECT sensor on the head and the ECU do not start the fan. AFAIK, the connection from the fan circuit to the ECU is only for monitoring purposes to estimate electrical load. If the thermo switch at the thermostat does not close, the fan will never start and the engine will overheat.
Look for burnt contacts in the underhood fuse box where the relay and fan fuse plug in. You may need to replace the box.
That's what I meant, I unplugged the ect switch from the thermostat housing, shorted it, trying to cause the fan to kick on, and it still didn't come on, so I bought a brand new relay from Honda, put the relay in, and it still didn't come on, but I know they the relay is good because it's brand new. So I bought a new ect switch. Gonna put it in later and hope it works.
Re: Radiator fan wire going to fuse box under dash
Originally Posted by mk378
Fan relay is controlled by a thermo switch on the thermostat housing, where the lower hose connects to the engine. Jumping this switch should cause the relay to close and the fan to run as soon as the key is turned on.
The ECT sensor on the head and the ECU do not start the fan. AFAIK, the connection from the fan circuit to the ECU is only for monitoring purposes to estimate electrical load. If the thermo switch at the thermostat does not close, the fan will never start and the engine will overheat.
Look for burnt contacts in the underhood fuse box where the relay and fan fuse plug in. You may need to replace the box.
Also, no burnt contacts in either fuse box. The switch itself is the only other thing I can think of.
Re: Radiator fan wire going to fuse box under dash
Unplug the relay and jump between the two sockets for the contacts of the relay. This should run the fan even with the key off because it runs battery voltage direct from fuse 33 to the fan. If fan does not run, trace the voltage through the circuit to see where it is being lost.
The relay coil terminals in the box, one should be live with the key on and the other should have continuity to the thermo switch. Also check continuity of the thermo switch black wire to ground.
03-17-2016, 03:38 PM
Radiator fan wire going to fuse box under dash
