07 M35 Electrical Fans always on [SOLVED - fan control module]

[2.7t]

I noted recently that the electrical fans are staying on on my car. It stays on even when the engine is off but the car is in accessories mode. The fans get on at full speed WITH engine off and on. I have been told there could be a bubble in the coolant system but can seem to justify why that would cause the fans to come on in accessories mode (engine off but all lights on dash illuminate and radio work)

Even at cold starts the fans are at full blast sometimes they will trickle down to low speeds but still on.

And AC is OFF

[Ilya]

The reason why it turns on in ACC mode is because the ECU is detecting that the temperature of the car is *insert here* and is thus racing the fans. Does it do this when the car is cold (hasn't been on in a hours)?

[2.7t]

The reason why it turns on in ACC mode is because the ECU is detecting that the temperature of the car is *insert here* and is thus racing the fans. Does it do this when the car is cold (hasn't been on in a hours)?

Yes the fans start on cold ignition.,Infact the fans starts on a cold overnight engine with engine off and the car in accessory mode. When I say the fans are ALWAYS on, I mean ALWAYS. 40F outside, cold engine, hot engine....although on a hot engine the fans slow down but not turn off. If i do a Battery Disconnect it should reset the ecu...would this help? the Coolant temp needle stays where it is desired, does not sway.

[Ilya]

You can try a reset but it might be something with the fan controller itself...

[The00Dustin]

in accessories mode (engine off but all lights on dash illuminate and radio work)

Even at cold starts the fans are at full blast sometimes they will trickle down to low speeds but still on.

And AC is OFF

In a 06, the dash lights don't all illuminate in accessories mode. In fact, I can't even see the odometer numbers in accessories mode and hove to switch to on mode in order to see them. This may have changed in 07, and even if it didn't determining that the fans aren't actually on in accessories mode might not be helpful in diagnosing / resolving the issue. However, in order to be sure, in case it could help, to get into accessories mode in my 06, I either press the start button once from Off WITHOUT pressing the brake OR press the start button once from engine running while at a complete stop with the transmission OUT of Park (in Neutral, for instance). When I do this, the light above the Start button says ACC instead of ON. I think it is dumb that the odometer doesn't come on in accessories mode, and it's certainly something they could have changed for 07, which seems likely since you bolded "AC is OFF," but if you're hitting the start button twice in order to get all the dash lights on, then maybe the fans aren't actually running in accessories mode?

The reason why it turns on in ACC mode is because the ECU is detecting that the temperature of the car is *insert here* and is thus racing the fans. Does it do this when the car is cold (hasn't been on in a hours)?

I really don't know, but are you sure about this? It seems pointless to run the fans when the water pump isn't running, so I wouldn't expect them to come on in accessories mode regardless, even if they do come on without the engine running in on mode simply because it's safer to assume the engine is running in on mode than it would be to actually only run them when an RPM reading is picked up.

You can try a reset but it might be something with the fan controller itself...

Wasn't there a post recently about a fan relay going bad on a model year around this age? Seems like maybe the dealership wanted to replace something big and it was actually possible to just replace the relay. Assuming resetting the ECU doesn't help, could it be a relay vs a controller?

[Ilya]

Sorry, I meant ACC as actually 'ON' mode. I agree with you, in ACC only basically the radio should come on. If in 'ON' mode the fans turn on with the car cold...something is telling the ECU that the temperature is high and hence it's running the fans.

And yes, the fan relay was discussed in this thread. Good call.

post6681415.html?hilit=fan%20relay#p6681415

[MasterDent]

Had the same issue 07 m35, went to the dealer he said the radiator valve is stuck open and needs replacement, 220$ cost!

[2.7t]

Had the same issue 07 m35, went to the dealer he said the radiator valve is stuck open and needs replacement, 220$ cost!

UPDATE: The issue was the fan control module. Replaced one with new from Infiniti $55.00. Easy DIY hardest part is removing the Pins without breaking them off the old module.