Radiator Fan not functioning

9krpmrx8 · 12-04-2017, 01:12 PM

Okay guys, so I had the coolant hose from the Tstat to the head bust, the plastic fitting was completely rotted.

As preventive maintenance a few months ago I replaced the water pump, tstat, radiator, and most of the coolant hoses and the car has been running fine until this hose fitting failed.

So, I was pulling into my driveway and the light came on saying the engine temp was too high. So I used Carly to see that coolant temps were at 230F.

I let it cool down for a few hours and then started it up and let it warm up, watching the temps and noticed when it got to 220F the fan was still not on. So I turned on the AC and the fan still did not come on.

I shut it down and checked the fan fuse in the fuse box and it was fine.

So, then I searched for codes and found this:

Electric fan, actuation: Line disconnection

The diagnostic function monitors the wire
between the electric fan and the DME

The fault is recognized when
the electric fan has no power
supply.

I checked the wiring harness and the sheathing and wiring is all in good condition with solid grounding, etc.

So I am thinking my fan just died but from what I can find from searching there does not seem to be an easy way to verify this without taking apart the harness to try and power up the fan.

I also read certain scan tools can activate the fan so I may have to have a shop check it since I do not have one.

Also am I correct that there is no fan relay?

rich_mane · 12-04-2017, 02:50 PM

BMW ISTA can activate the fan but if it's showing a line disconnection, that likely won't do much of anything.

Looks like there's a relay according to realoem but I've never had to replace one.
http://www.realoem.com/bmw/enUS/show...diagId=61_3964

Did you disconnect the fan connection and check the contact points in there? Maybe there's some corrosion in there causing the disconnect. If not then I'd throw that relay in it and if it's still not working go straight to replacing the fan.

9krpmrx8 · 12-04-2017, 03:39 PM

Ah thanks man, I never thought to search for a part there. I did test the pins on the connector and was only getting 4.5V but I had no specs to go by and the info i was finding is apparently incorrect if there is a relay.

9krpmrx8 · 12-05-2017, 09:41 AM

Okay so I tested the relay and it is functioning properly. I applied 12V to the fan directly and nothing happened so I am pretty sure the fan is dead.

12-04-2017, 01:12 PM	#1
9krpmrx8 Clean is the new cool, keep it that way. 808 Rep 1,685 Posts Drives: 11' Alpine White 335i Sedan Join Date: Jan 2016 Location: San Antonio, Texas iTrader: (0)	Radiator Fan not functioning Okay guys, so I had the coolant hose from the Tstat to the head bust, the plastic fitting was completely rotted. As preventive maintenance a few months ago I replaced the water pump, tstat, radiator, and most of the coolant hoses and the car has been running fine until this hose fitting failed. So, I was pulling into my driveway and the light came on saying the engine temp was too high. So I used Carly to see that coolant temps were at 230F. I let it cool down for a few hours and then started it up and let it warm up, watching the temps and noticed when it got to 220F the fan was still not on. So I turned on the AC and the fan still did not come on. I shut it down and checked the fan fuse in the fuse box and it was fine. So, then I searched for codes and found this: Electric fan, actuation: Line disconnection The diagnostic function monitors the wire between the electric fan and the DME The fault is recognized when the electric fan has no power supply. I checked the wiring harness and the sheathing and wiring is all in good condition with solid grounding, etc. So I am thinking my fan just died but from what I can find from searching there does not seem to be an easy way to verify this without taking apart the harness to try and power up the fan. I also read certain scan tools can activate the fan so I may have to have a shop check it since I do not have one. Also am I correct that there is no fan relay?
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12-04-2017, 02:50 PM	#2
rich_mane First Lieutenant 139 Rep 227 Posts Drives: 2011 E92 335i Join Date: Jan 2016 Location: S.FL iTrader: (1)	BMW ISTA can activate the fan but if it's showing a line disconnection, that likely won't do much of anything. Looks like there's a relay according to realoem but I've never had to replace one. http://www.realoem.com/bmw/enUS/show...diagId=61_3964 Did you disconnect the fan connection and check the contact points in there? Maybe there's some corrosion in there causing the disconnect. If not then I'd throw that relay in it and if it's still not working go straight to replacing the fan.
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12-04-2017, 03:39 PM	#3
9krpmrx8 Clean is the new cool, keep it that way. 808 Rep 1,685 Posts Drives: 11' Alpine White 335i Sedan Join Date: Jan 2016 Location: San Antonio, Texas iTrader: (0)	Ah thanks man, I never thought to search for a part there. I did test the pins on the connector and was only getting 4.5V but I had no specs to go by and the info i was finding is apparently incorrect if there is a relay.
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12-05-2017, 09:41 AM	#4
9krpmrx8 Clean is the new cool, keep it that way. 808 Rep 1,685 Posts Drives: 11' Alpine White 335i Sedan Join Date: Jan 2016 Location: San Antonio, Texas iTrader: (0)	Okay so I tested the relay and it is functioning properly. I applied 12V to the fan directly and nothing happened so I am pretty sure the fan is dead.
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