my car is overheating whenever i am in traffic. the problem is the fans, the radiator fan doesn't come on when it should or at all, and i can't keep the engine cool by turning on the ac and getting the condenser fan to run.

so neither fan will turn on when it's supposed to. i have FAL fans and you can tell when they are on. they DO turn on when connected straight to the battery.

i have:

-checked the two fusible links for each fan
-checked the relay for each fan
-checked the coolant temp sensor, it's within the specified resistance range
-checked the ground g04, and it looks fine (there is continuity from the fan harness to the ground)


anyone have similar problems? based on what i've done, im thinking it's either the ecu or connection somewhere. doubt it's the ecu though.

where are likely trouble spots for a bad connection?

 

Try shorting out the relay contacts to see if the fans kick on. If it does, then you've eliminated half the circuit, and it's likely the ECU.

(on the relay base, short the two large blades)

 

Hoping this will help with testing/diagnosis, but whenever you turn the AC on, the radiator fan should turn on (yes, both the radiator and AC fans turn on with AC, at least on my car..)

I would use an OBD2 reader to see what coolant temperature the ECU sees though (with AC off, rad fan turns on at around 204F)

 

some info on fal fans,

FAL fans are hooked up to the regular radiator fan plug. They are not separated for the 2 fan plugs in the car. If you turn on the AC it automatically kicks both fans on but if your wired to the regular plug, it will turn them on as well.

 

so i shorted out the relay pins (great idea by the way) and the fans kicked right on. so it is something to do with the wiring from the sensor to ecu, ecu to fans, or the ecu itself.

i tend to doubt the ecu is bad. so im guessing it's a problem with the sensor to ecu wiring. im getting a usb to serial adapter so i can read from the obd port.

thanks for the suggestions guys, i'll report back.

 

If you feel like digging and removing the ECU connector, you can check to see if you're wiring is good from the sensor to the ECU by testing between pins 71 (ground) and 78 for the sensor resistance.

If you decide to do that, check continuity from the rad fan relay contacts to pin 45.

 

yeah, i was thinking of that. i really don't want to do it though, that ecu is a PITA for me.

 

so, this problem is still happening, and becoming a huge pain in the ass for me with the hot weather around here lately. I got a serial to usb converter cable, and was able to check and see that the ecu is in fact getting an accurate reading from the temperature sensor.

so it is one of two things:

1. bad ecu
2. bad wiring from the ecu to fan relays


anybody experience this before and have a likely culprit?

 

Since it's becoming such a pain in the ass, you can consider buying a separate fan relay kit with temperature sensor (ebay has a lot of them). Some sensors you can just stick to the radiator. The additional benefit would be that you will be able to set the temperature when fans kick in to whatever you want

 

i have thought about that, but i would like to fix it for free if possible. i also don't want to waste time taking the dash all off in this heat to look at the connector if it's fine too, but i guess i will have to do that to eliminate that possibility.