Everytime I put the ignition to the "on" position, my radiator fan automatically kicks in at full speed and drain my battery if I don't start the car.

Once the car is started they go off and go on when engine is hot enough as they normally should.

My A/C and airpump where removed and the fan relays are switch were not modified or anything. What could be the cause ?

Everytime I want to work on the car or just listen to the radio without having the car running drains my battery and it's driving me nuts.

Thanks!

 

check your fan relays

 

Is it the 4 relays on passenger side near the shock ? How can I test them ? with a Voltmeter ?

Thanks

 

The procedure to test the relays is in the FSM. Its a bit confusing but doable.

Also, check your electrical system to make sure your battery is holding enough of a charge.

This happened to me once but I forgot whether it was a crappy battery or a problem with the relays or wiring from the relays to the fans.

 

Stupid quiestion but is the AC button pushed in for on? That will cause your fans to come on, i know you said your AC was removed but what part of it?

 

i am having the same problem here!!!! need some help..

 

This happens to me except ONLY when the car is really hot.

I always thought this was normal.

Say for instance if the car is at 190F+ and engine OFF but key in "on", the fans will run til temp goes a bit lower.

If i pull key out, fans go off.

However if the car is heatsoaked at like a lower temp of 140-160F etc, with key in "on" position, the fans are OFF.

So i always thought it was a temperature related procedure.

 

3 Most likely causes (in no particular order).

1) Relay stuck closed.
2) Thermoswitch broken.
3) Wire to Thermoswitch shorted to ground.

The Thermoswitch is a real pain to get to, so I'd start testing at the relay. It's pretty trivial to test relay function and the lead to the thermoswitch. (If your thermoswitch is bad, replace it with the FC version, it comes on at a lower temp.)

If you don't have the manuals and you don't know how to test a relay, take it to someone who can.

 

are u running the oem ecu or a pfc?

 

Mine does the exact same thing. I always thougth this was normal too. I'm running a PowerFC.

 

if the coolant is over 90 degrees shouldn't the rad fans come on?

 

I had the same exact problem with a faulty pfc unit

 

Yeah...this is the way it is SUPPOSED to work. My fans run if the engine is sufficiently hot...plain and simple, even with the engine off and key removed.

ALL my cars are this way....that is the reason they have that BIG warning emblems that says, "CAUTION! Fans may come on at ANY time. Keep hands clear."

 

The fans run with the key out??

That doesnt seem right though.

Because key in "on" position open the relays.

 

Yup. Whenever I pull into the garage on a hot day usually the fans are running and continue to do so for a few minutes....then they turn off. Never have had a problem except for when I did the 'fan mod', then the damned things would NEVER turn off.

 

Yeah my fans do that too if i leave the key to the ON position.

I would be a bit worried if ANYTHING like that works with the key out of the ignition. Thats like an electrical problem evolving lol

 

My fans were hard wired like that from Japan. I didnt have any problems and prefered it to how the stock system works. Its very handy for cooling the car down when the car was stationary. I never saw higher then 83'c temps even in traffic

I know your expressing a problem, but thought I would throw that in

 

Check your PFC settings (I'm assuming that's what you're using for an ECU with a single turbo).

If the thermoswitch was broken or shorted, the fans would stay on even after the car was started, because the ECU would think that the coolant temps were over 214 degrees F. Same with the relays; there is power to the relays even with the ignition turned off (the reason that the 5-minute shutdown sequence update works after removing the key).

 

The cooling fans are supposed to come on even after you take the key out because the thermostat is set to open when the coolant reaches a certain level. it's normal and is supposed to cool the car after you park. I always thought it was weird too, but it's also incorperated into some honda's too.

 

^^can someone verify that?

I dont know how that make sense though as when you turn the key to the "on" position, you open up the relays. How can the fans work with closed relays??

 

This was part of the fan tsb. Mazda added the small black relay box you find behind the ecu. There was also a jumper harness, but this harness is built into the new engine harnesses. What it is supposed to do is run the fans for 10 min after shutdown under certain conditions, but I have only seen it work maybe a handful of times.

 

That or maybe when the car is SEVERLY heatsoaked like over 225F or something.

I never let my car get up to 220F.

If im driving and temps go up, i hit the fans. When i shut down, i pop the hood and let it cool off right away. Or i run the fans for like 3-5 minutes if i dont wanna pop the hood (crowded areas, windy conditions, nosey people etc).

 

If you shut the car off when the coolant temp is over 214 degrees F (not uncommon in the past for average everyday owners who didn't know about the heatsoak problems, didn't have a manual fan mod, ran in hot climates, no accessory coolant temp gauge, etc.), the fan update will run the fans with the car shut off, often times a minute or so after the ignition has been shut off.

Try inserting a voltmeter into the relays and you'll see that they're powered at all times. The relay operation doesn't really depend on power; they operate (close) by a lead being grounded.

 

^ Ah! That makes sense.
My Volvo runs the fans after I shut it off, and so does my Mariner....as well as the FD.

 

Damn i didnt know that. I would have to do a test to see if mine will do that.

Although i dont remember my fans going on at all without the key, and i KNOW i have heatsoaked past 214F before. Hmmm