My cooling fans aren't working. I replace the fan with a brand new fan yesterday still nothing. I checked the fuse that's in front of the battery both of them. Both fan fuses seem to be intact.

What else is in the circuit that I need to check? Like other switches and fuses? I am currently investigating replacing the relays that are in the ipdm Box, but I thought Windows go out your fan keeps running not does it run at all. I replaced one of those previously I'm trying to replace the other two now to see if that's the problem. Just wondering if anybody has any other suggestions. Thanks

 

Those types of fuses have to be tested in order to check out, not just by looks. The fans turn on when the ecu tells it to turn on when engine reaches a certain temp or the ac is on. Couple things first, you're sure the connectors aren't in the reverse order on the fans? Do the fans come on if you turn the ac on? If you must drive this way turn your heat to max to steal heat from engine bay and watch your temp gauge carefully

 

When I was new to my car I tried to start a relationship with my infiniti dealer and keep a history of my car. I went in because car was overheating. First the bill started at $400 for one new fan motor. Later they called me saying I need both new motors. Finally they said I need a whole new fan shroud assembly for a total of $1200. Bitched my way down to 900 I think. I felt uneasy about the whole thing like they didn't have part #'s for me and such. Told them to save old parts and I got back my fan and a fuse. I had my bumper off a week later and decided to put my old fan back in and sure enough it worked perfectly. Ran my old fan for 2 years after that and had the $800 fan sitting in my garage that whole time. Needless to say I believe they switched out a fuse and replaced my fan for the money(service advisers make commission). Went back to talk with the service manager and guess what he said? "Well did your car overheat when you drove off our lot?" I said no. "Well to me it looks like we fixed your problem." So I filed a report with infiniti and it wasn't even looked into. I wouldn't go back there unless I had to take a **** honestly. Sorry to vent but hopefully we can help you avoid going to the dealer. Not saying all dealers are bad, but they definitely have some bad apples at my dealer. I now go to nissan

 

Thanks. I will check them for continuity.

Possibly. I had to splice new harness plugs on, so my harness lengths aren't original. I'm pretty sure I did it right, but I could have them switched. Can you tell me which set of colored wires go to which fan? And which fan is which? I'm assuming that the A/C on is on the driver's side

No. Neither fan comes on, even with the A/C and at temperature.


I tried that briefly, but I have to much stop and go traffic without the airflow that you'd get at normal speeds

 

Did you provide direct power to the fans before replacing them?

There are three relays in the box and I don't remember the order, but depending on which ones are off/on it controls off, low, and high settings.

To test a relay properly you'll need a multimeter and two jumper cables. The two thicker plugs usually are the ones you provide 12V to and it will then click. Then you use your multimeter to check for continuity on the other terminals.

Don't just say the relay is okay if you hear it click. Read the FSM it will tell you what terminals you can check for continuity from the ipdm to the fan. If your wiring is good then it could be a bad ipdm or ECU would be my next guess.

 

If you had to splice the connectors in then, I would double check your work. The connector on the bottom of the fan plugs into the left fan. The other connector is for the right fan, I just took some test leads from my battery and put them to my motor connectors. My fails spun real slow, so I knew my fan motors were shot.

 

no I did not test the fans. I have a lifetime warranty at O'Reilly so I just went and swap them out from a brand new one after testing my wire splicing on the old and having it not work. I kind of checked and double-checked it the only thing that concerns me is if I have the grounds correct. Each plug has a different set of colors for the wiring but each one has a common color black wire of the 4.

I switch the grounds back and forth to see if that was the problem and it wasn't. I think on my splice seems okay again but I will double check. I did not try simply switching the plugs to see if they would come on. But I assume that at least one of them would have came on if they were plugged in backwards and they were actually working in the scenarios that I tested. I had the AC on, and allow the car to get up to temperature even run slightly hot hot enough that the fan should have come on.

 

What would happen if the connectors were reversed? I have a similar problem. When ac is on, fans kick in and all okay. Does not work when ac is off. Any advice?

 

Will the vehicle actually overheat though? The fans don't even turn on until 208 degrees F.

 

EDIT: Lagged and double posted.

 

I realize this is an old thread but hope this helps others to resolve this issue with a minimal amount of emotion and energy expended and/or money spent.

To properly diagnose electrical issues you should start with a circuit schematic diagram of the system. Studying the diagram will allow you to understand where the power starts, the wire colors it travels in, the connectors the power goes through, the relays that control the power, and wiring/connectors all the way to the fans (or electrical item/load). A clear understanding of what is working/or not working and a good understanding of the circuit diagram will allow you to consider what is most likely causing the issue. Next, where is the easiest approach to testing and confirming your suspicions? If no idea where to start, divide (break the system down in half) and conquer (test each half) to see if results are as expected.

I'm currently working on a 2005 G35, both cooling fans not working. Unable to turn on fans (either hi or low speed) with scan tool. Looking at schematic, relays 1 and 3 control fan power (12V) to each fan motor depending on speed desired from ECM and relay 2 is the ground side (power return) for both fan motors. All 3 relay enable coils are supplied by 12V that is used on other circuits/systems that work. Each relay is enabled/activated by a separate low signal from ECM. So... I suspect there is a problem with relay #2 or #2 control. I removed battery and IPDM cover and ran out of time. Pulling #2 relay and jumping the contactor terminals with jumper wire with complete the gnd circuit and fans should work if my suspicions are correct. I'll let you know what I find.

 

Technically the signal comes from the ECM via CANBUS but the IPDM does all the relay switching independently via the CPU in the IPDM. Low speed only relay 1 will close and relay 2/3 will be open. High speed all relays will be closed.

Typically it's easiest to pull all 3 relays and bench test them to make sure both poles are closing on each relay. Should be this style of 2M relay. Apply power to 1,2 to close the relay then make sure there's continuity across 3,5 and 6,7.

 

Well... a fresh look at the system revealed I should have simply back probed the right (pass side) fan connector to confirm power and ground. Power good on both high and low wires. Ground good too. Hmmm... give the fan a little push and it slowly starts to spin. Spin the driver side fan, it starts too. Both fan motors failed. Both motor bushings feel good, no slop/wear. Ordered replacement motors. Will update when installed.

Cleric, you are correct. Fan relay control signals come from IPDM CPU via CANBUS. Side note - never hurts to load test relays to insure they can handle the current (old style glass halogen hi/lo beam headlamp) vs continuity test only.

 

Fan motor failure is fairly common on this platform, when you get the new ones in don't be surprised if it "appears" that one fan is spinning faster than the other. They have a different number of blades on the two fans.

 

Is there a link/post to what's 'normal' operation for radiator fans for comparison sake? I'm 3 fan assembly's in now, so lost my baseline.

------- Skip this part for the actual question, just my history------ I got a 'free' AC check at a shop and was told one of my fans wasn't working, so I replaced the assembly (probably overkill after reading other posts recently). 1 month after the replacement warranty ended for that I was having overheat problems, took it into another place and the driverside fan had dismounted, but was still spinning and cutting into the radiator. So now 3rd assembly just runs super loud, when complained to shop they asked if the car was holding temp, and when I said yes, they said "then it's fine" So now I have to troubleshoot it myself in order to find out if they need to do some more work.
-------

DS- Driver-side fan
PS- Passenger-side fan

What's happening currently, tested on a 60F day:
--Cold start- neither fan running
--cycle A/C- PS turns on w/ AC, goes off when A/C turned off (car was up to half norm op temp during this test)
--Idle w/ A/C on til engine at norm op temp- no change, just PS on.
--turned car & A/C off, let sit for 5min and started engine- no fans running
--cycled A/C again, PS fan still on w/ A/C on, off w/ A/C off
--Freeway speeds for 2 miles, came to a stop at IDLE, and PS fan came on for a min, then went off, then just cycled on/off a couple times while IDLE'ing there
Of note:
DS fan hasn't been witnessed coming on.
For a week, after highway driving duration's of 50min the PS fan has been on & loud when slowing enough to hear, to engine shutdown.
Temp hasn't gone above norm op temp.

So questions:
What makes *EACH* fan (driver side/passenger side) come on, turn off...change rpm?
Is each fan supposed to have 2 speeds (low/hi), or is one of the fans the low, and the other a high?

Trying to figure out if I have a thermostat problem, they mis-connected the plugs from the fans (backwards?), or if they installed a bum fan assembly....or something else?