I recently installed a engine tucked harness in my 92 si Eg . My car was overheating. I replaced the fan relay with 3 different ones , didnt make any difference . i jumped the fan switch , that didnt work either. Like theres a shortage in the underhood fuse box. Before this overheating problem, the fan relay was opening and closing alot (can hear scratching noises) I tested with circuit tester the fan relay terminals . It lid up on Top and bottom Left terminals. Also it had 12.15v running on Top and bottom Left terminals. Right Top and Bottom terminals had no power at all (i think it normal) . Than that noise went away , as if there was no power going to the fan relay at all now, and the overheating occurred. I was overheating yesterday for hours, than i went to a restaurant and came back after 2 hours started the car and drove it for 100 miles with no overheating issues, fan was turning on. I also checked all my fuses they are good, and i even replaced the hood fuse box. How can i find the bad wire. Thanks

 

I had this problem with a 93 del sol. If you drop the blower motor and look at the wire connection you may see a lot of corrosion causing a big current draw and the relay will get real hot. I replaced the blower motor and made a fresh hard wire connection. That area location seems to collect moisture right on that connector. It draws a lot of current also.

 

are you talking specifically for the blower motor connector ? i Think its 2 or 3 pin, how can i check if it making that current draw back?

 

I assume you're talking about the radiator fan relay in the hood fuse box.

If you run power and ground wires from the battery directly to the radiator fan connector, does the fan run?

 

yes

 

Yeah I misunderstood I was talking blower motor fan.

 

Unplug the fan switch on the thermostat housing.

Turn key to ON(II).

Measure voltage to body ground on the Yel/Grn wire pin in the free connector.

Post voltage reading.

 

12.16v

I just drove the car 250 miles and it didnt overheat at all. and my relay wasnt opening and closing non stop atleast i didnt hear the scratching noise. this happens once in a while but i want to figure it out ,

 

Can't troubleshoot until problem recurs.

 

You don't need the fan if the car keeps moving, because that forces air through the radiator. It should only need to run while stopped or moving slowly in traffic.

Look for melted or burned contacts in the fuse box where the fan fuse and relay plug in, and where the harness plugs plug into the box.

The circuit is real simple. A key switched circuit (from an under dash fuse) supplies one end of the coil. The other end of the coil is grounded by the switch closing. The contacts are fed from constant battery power through the fuse in the underhood box. The other contact goes to the + side of the fan motor. The motor is grounded to the fender ground.

 

It didn't overheat on your 250 mile trip because you were giving the radiator alot of cooling air.....

 

.. My car overheated few times on a 100 mile road trip before . That cooling air you talking about is not enough for the gauge mark to constantly stay under half mark. Without the fan turning on and helping with cooling.
I'll check the yellow wire running under the dash fuse box

 

Are you saying that there is no power on any of the relay pins now?

If so. check fuses, should be 2 of them, one is for the rad fan, the other in under dash fuse box is for the relays coil, one pin should be hot at all times, the other may need the ign. on.

If fuses are good, check "tucked harness", you may have to do a continuity check on the 2 power lead to the pins on the relay plug. 94

 

No im only saying that theres probably a short circuit or voltage drop only at the radiator fan relay , the other 2 relays dont have problems. and this problem doesnt occur every day idk

 

Jump the thermo switch plug, turn key on (no need to start engine), fan should run all the time. Wiggle wires, connectors, relay, fuse, etc see if you can get it to stop, that would be where the problem is.

 

When the problem occurs once in a while , my fan wasnt turning on at all, i did the jumping technique and the fan didnt turn on . i parked the car for few hours came back and the fan was working.

 

As mentioned, you can not troubleshoot a problem until it occurs, next time it is not working check for the 2 powers at the rad fan relay plug, if both there, jump the thermos switch if still not working, jump the relay, if still nothing, the problem is between the relay and the rad fan, check the wiring. 94