I have this problem with my Evo 8 that lately I have to jump start it everyday. I have a new odyssey pc680 battery (replaced because it was faulty). As soon as I turn on the switch on the ignition the Radiator Fan turns on all of a sudden (has never happened before). I can drive the vehicle and turn it off and it will not restart. I checked all the fuses and lights but I can't seem to find why it's draining that fast. The charging system is working fine, I can unplug the battery and accelerate and car stays on, voltage when car is off shows 12.96v, as soon as I open the ignition fan turns on and drops to 12.32 volts and car won't turn on. Like I said I can be driving it and turn it off for 5 seconds and it won't turn on. What's happening?

 

You sure it's the battery?

So when you start it, and it's dead cold the fan turns on?

When you say it won't start, do you mean it cranks and cranks and cranks but won't fire?

What mods?? IE sound system, turbo timer, any gauges? Basically any mods that draw power?

We need more descriptive info please. Best thing to do, take a video with your phone upload it to YouTube. Link it to this.

 

Yes dead cold and the fan starts, it does not crank it just Clicks. No sound system but I have gauges and an alarm but makes nonsense why it won't start up right after I turn it off. With old battery which was the same pc680 I had no problems with it until one day I destroyed it by completely draining it and could not resurrect it.

 

I would check the coolant temp sensor, do you have evoscan or know someone who does?

By chance did you tap the battery terminals togther while tightening? I would check for wire chaffing around the ground cable coming off the neg battery post. Same with positive side.

Also try hitting the starter with a hammer. Cause you said charging system is good. And even the cold battery reads in the 12v area.

Leads me to believe your grounding out somewhere, or you starter is about done.

When you jump start your car is the other car running?

 

If he was grounded out and someone tryed to jump start him wont that bog the car down that was trying to jump him?

 

Get a DMM and pull fuses until you notice the parasitic drain goes away.

 

dont unplug the battery and rev the car. test it with a different battery and see if its does the same thing

 

could the fan coming on could be the control module located on the fan housing?

do you have an alarm on the car?

 

did you try another good battery?

 

Take the starter off the vehicle and test it. If its good, you can eliminate that..

 

As per odyssey the battery needs to be no less than 12.64v if I recall in order for it to crank, the battery seems to be draining real quick as soon as you turn it off. Again I also have no clue why the fan now decides to turn on as soon as the ignition is open.