2002 V70XC radiator cooling fan will NOT turn on

[gmbooth]

Hi everyone, Newbie here! My 2002 V70XC radiator cooling fan will NOT turn on. I've seen posts of the fan not tuning off which was my original problem. Now with the new replacement fan it will not turn on. Just my luck! LOL Is there anything to check between the "purple wire" back to the EMC that might cause it NOT to turn on? Any help would be really appreciated!

[Xfingers]

I've taken my fan out of the engine compartment and put it back in several times when working on the car but haven't had the problem of the fan always running and not shutting off (yet). I would think there might be a fuse somewhere you could maybe pull to see if it's burned out? Of course, double-check your electrical connections to the fan. Is the replacement fan new or used? FWIW, if I was in your situation and had run out of ideas, I'd probably reinstall the old fan and see if it runs non-stop like before. If it does, then maybe the new fan or its electrical connectors are faulty. If it doesn't, I'd guess you've got an electrical issue somewhere else.

How much driving have you done with the new fan? Enough to generate sufficient heat to trigger the fan? Is there a heat sensor/thermostat somewhere which measures the coolant temp and decides when the fan should start/stop? Could this be the issue? Sorry, I can't be better help. Maybe some other members with more experience with the problem will reply!

[ericjp]

If you still have the old fan plug it back in and see if it comes on. If it does then you know the main power is good, and the only other issue is if it's not getting a signal to turn on. Always a possibility that the new fan is bad.

[gmbooth]

[QUOTE=gmbooth;202140]Main power is good. Old fan kept running and drained the battery! This is the second new fan I'm trying. Neither worked. Power is there and continuity is good on all connectors. It's not a OEM Volvo fan but it is from a reliable manufacturer. That's what I'm trying to figure out if there is anything between the ECM and the fan module that I can check. Ran the vehicle long enough for message "Coolant Temp Too High" or something like that. Fan never came on. Thanks for the help though! Will keep searching in the mean time! {:>)

"Is there a heat sensor/thermostat somewhere which measures the coolant temp and decides when the fan should start/stop?"

"And the only other issue is if it's not getting a signal to turn on."

This is what I'm checking for, is the signal directly to/from ECM to Cooling Fan Module or ECM (Fuse/Relay/Sensor) then Cooling Fan Module?

[gmbooth]

[QUOTE=gmbooth;202140]Main power is good. Old fan kept running and drained the battery! This is the second new fan I'm trying. Neither worked. Power is there and continuity is good on all connectors. It's not a OEM Volvo fan but it is from a reliable manufacturer. That's what I'm trying to figure out if there is anything between the ECM and the fan module that I can check. Ran the vehicle long enough for message "Coolant Temp Too High" or something like that. Fan never came on. Thanks for the help though! Will keep searching in the mean time! {:>)[the only other issue is if it's not getting a signal to turn on/QUOTE] That's what I'm trying to find out how or where is the signal generated ECM directly to Cooling Fan Module or ECM (Fuse/Relay/Sensor) to cooling fan.

[ericjp]

Does it come on if the AC is on? I'm not sure if there's a fuse for the ECM that controls the fan.

[Willy]

The wiring diagram is for MY2004, but I believe MY2002 is the same:
8825

[gmbooth]

No it doesn't. I'm afraid that I'm looking at replacing the ECM. Thank you ericjp for the reply.

[gmbooth]

Thanks Willy! Looks like a new ECM is in my future.

[Willy]

In case you are interested in the wiring diagrams, I dropped them here
a while ago for a member to download them.
https://www.sendspace.com/file/h5hxjt
Since I haven't deleted them, they can still be downloaded :)

[sjonnie]

This is what I'm checking for, is the signal directly to/from ECM to Cooling Fan Module or ECM (Fuse/Relay/Sensor) then Cooling Fan Module?
The ECM produces a PWM signal which requires an oscilloscope to read it correctly but you can at least check that there is a voltage on the signal wire to eliminate the possibility of a break or short. If I remember correctly it's a purple wire. Insert a single copper strand from a multi-strand wire into the fan connector on the purple wire and check the voltage between the wire and ground. The voltmeter will give you an average of the PWM signal voltage which should be somewhere between 1.2V and 10V. If there's no voltage then check the output at the ECM to make sure it's not a wiring fault.