2004 Nissan 350Z Unknown Overheating Problem
 

I'm brand new to the forum, but i'm not sure where else to look.... Let me give a little background to the car first, its a 2004 Enthusiast Model, I purchased it back in August of 2018 with just under 52,000 miles on it, after about a month or two of driving, the car overheated while sitting in traffic, steam billowing out of the hood, it caught me off guard, it wasn't something I had expected from a car with such low miles... Nevertheless, I began trying to diagnose it myself, I figured I'd start by replacing the thermostat. I ended up buying an AEM one and putting it in, but it wasn't the issue, still overheating.... my next thought was to bring it to a Nissan dealership and have the issue properly diagnosed, which is what I did! The dealership had told me that I was going to need to replace the entire cooling fan assembly, and that the car was overheating due to the fans not turning on at all, which made sense, because as far as I know, that was a common problem with early model years of the 350z. I put off the installation of the cooling fan assembly until yesterday (about 4-5 months) The car now has 60,000 miles, and I installed the new fan assembly yesterday and the fans STILL wont turn on, I immediately brought it back to the dealership to have it rediagnosed, where I noticed that the fan fuse was blown. I replaced it with a new fuse, and still nothing. I've considered bleeding the system, but it still doesn't make sense to me that the fans wont turn on with brand new motors, etc. I'm at a loss, I want this issue resolved ASAP! I was hoping some of you may have some insight on what else to check, or anything of that nature. PLEASE help! I'm sick of the overheating!

Have you seen this thread:
https://my350z.com/forum/maintenance...-bad-ipdm.html

May give you an idea of some things to check. You definitely need to get the fans working to see if that's the root of the overheating issues.

The fans should come on when the AC is on. Also you can usually tell if there's air in the system if your heater blows cold with the car at operating temp.

I would be concerned that you ran for so long with the fans not working. You may have overheated several times which leads to bigger issues.

But for now, see if any of that info helps you get the fans working.

Thanks for the reply! Turning the A/C was the first thing I did when I installed the new cooling fan assembly. Unfortunately, they still wouldn't turn on. Also, I leave my heater on full blast to counteract the excessive overheating (Nissan suggested it) until I can get it fixed, it blows hot. Yes, I did drive about 4000 miles without working fans, but I am very careful about watching the temp gauge, if it gets to high, I park and let the car cool off for about 10-15 minutes each time, it doesn't get extremely high in temperature too often, but it's still annoying!

Sounds electrical. Check voltage and continuity along the harness and IPDM. FSM says you can test out the fan if you hook up the battery directly to the fan motors after disconnecting harness. If they work, I would probably ghetto rig it with a manual on/off switch or wire into ENGINE ON until I get it proper fixed. Better than a blown up motor.

Found this on a UK forum:

If the cooling fan does not operate during a auto active test there are 3 suspect items:

1) Cooling fan motor malfunction
2) Harness malfunction between IPDM and Fan motor
3) IPDM Relay malfunction

The IPDM relays simply switch power via a 40 Amp fuse to the Fan Motors, controlled by the CAN bus.

My next move would be to put the relays back in place and complete another auto test with a volt meter connected to the fan plug, if you get 12v this discounts items 2&3 above.

If you do get 12v then the fans are at fault, these can be replaced separately looking at the manual.

If you don't get 12v then it looks like it could be the relays/ipdm/ecm or can bus (which would involve Nissan to test further)


In your situation, I would suspect a bad relay since they get cycled a lot during normal driving conditions and your Z has matured even though the actual mileage isn't very high. Still just one more thing to check if you've been able to determine continuity across the wiring harness.
Good Luck!
-Icer