Hi all new here even though i have been to this site many times looking for how to's.
Some time ago i took my 2005 s60 2.5T AWD 96k to a shop because my radiator fan
was always running on high. It will shut off when i shut the car off but as soon as i turn
the car on it zooms to high speed and stays on high.
My worry is that i will prematurely kill my fan.
The tech at the shop said that he pulled a connector/plug "didnt say what plug or where it was"
and he cleaned it and plugged it back in and it worked.
He said that this fan uses 2 hot wires, one for each speed and the relay or module controls
wich speed to turn on and since one wire was not making good contact the other turned on
in its place.
So i have pulled the only connector i can see right on top of the fan. Once i pull that connector
the fan shuts off. I saw it has something like 8awg black and an 8awg red wire and also a 16awg
purple wire in the same connector. I pulled the connector out and cleaned the terminals with
contact cleaner but that didnt help it.
My next thing to check is the other side of the connector wich i believe runs to the module or relay
in the fuse box under the hood. does any one know how to take that fuse box out? i pulled off a
bunch of torx screws but it still was resisting me like it still had another screw or something.
any help would be greatly appreciated.
Radiator fan only runs on high
Hello DNA316,
Cooling fan has permanent 12 volts across the two heavy-duty wires when ignition is on. The thin wire carries the control signal from the ECM to the fan control module mounted on the fan. The signals to operate the fan are "pulse-width-modulated" on to this small wire, which has 12 volts or thereabouts on it all the time ignition is on. If you disconnect this wire the fan should not run at all. That would possibly show whether fan-control module is totally dead/short-circuit.
When I thought I had a problem with my cooling-fan not running, I could not work out how the fan worked. I found out how it worked on the interweb somewhere.... It was time to get my oscilloscope out of the garage....
Normally there is a constant 100 Hz square-wave "dip" on this wire, with respect to the constant voltage on it.
When the fan is meant to be off there is a narrow pulse ( not sure if it was 10 milliseconds wide ?, but thereabouts ) repeated at 100 Hz. When the fan is on at normal speed there is a double-width ( 20 milliseconds wide ? ) pulse repeated at 100 Hz. My fan starts at approximately 104 Centigrade, at which point the pulse doubles in width. Very clear to spot on an oscilloscope.
What you appear to need to do is prove whether the fan-control module on the fan is faulty, or is the ECM telling the fan-control module to run the fan all the time. If the ECM is telling the fan to run all the time, you will then need to look at other sensors etc.
I happened to have an oscilloscope due to my work, but I suppose that instead of an oscilloscope you could use an analogue multi-meter on AC volt range connected between this small wire and 12 volts. However, the small increase in the integrated voltage on that wire with the wider pulse when the fan is meant to be running, may be masked by the actual voltage fluctuations caused by the fan running. Scope will show the story, definitely.
Good luck, hope that may be useful in some way.
Ian.
Cooling fan has permanent 12 volts across the two heavy-duty wires when ignition is on. The thin wire carries the control signal from the ECM to the fan control module mounted on the fan. The signals to operate the fan are "pulse-width-modulated" on to this small wire, which has 12 volts or thereabouts on it all the time ignition is on. If you disconnect this wire the fan should not run at all. That would possibly show whether fan-control module is totally dead/short-circuit.
When I thought I had a problem with my cooling-fan not running, I could not work out how the fan worked. I found out how it worked on the interweb somewhere.... It was time to get my oscilloscope out of the garage....
Normally there is a constant 100 Hz square-wave "dip" on this wire, with respect to the constant voltage on it.
When the fan is meant to be off there is a narrow pulse ( not sure if it was 10 milliseconds wide ?, but thereabouts ) repeated at 100 Hz. When the fan is on at normal speed there is a double-width ( 20 milliseconds wide ? ) pulse repeated at 100 Hz. My fan starts at approximately 104 Centigrade, at which point the pulse doubles in width. Very clear to spot on an oscilloscope.
What you appear to need to do is prove whether the fan-control module on the fan is faulty, or is the ECM telling the fan-control module to run the fan all the time. If the ECM is telling the fan to run all the time, you will then need to look at other sensors etc.
I happened to have an oscilloscope due to my work, but I suppose that instead of an oscilloscope you could use an analogue multi-meter on AC volt range connected between this small wire and 12 volts. However, the small increase in the integrated voltage on that wire with the wider pulse when the fan is meant to be running, may be masked by the actual voltage fluctuations caused by the fan running. Scope will show the story, definitely.
Good luck, hope that may be useful in some way.
Ian.
Hi DNA16=
I hope you got your problem sorted out. The only way to get my 2003 S60's fan to stop running on high, even with the ignition off, is to unplug the connector on the fan shroud, so I'm guessing the fan relay has failed closed. The fan relay is on the underside of the fuse/relay board under the hood, but like you, I can't puzzle out how to get the board out. I take the TORX screws out, and there are two clips in front that are easy to undo, but It feels like it is still being held in and I don't want to force it and break the board. Did you ever figure out how to remove the fuse/relay board?
I hope you got your problem sorted out. The only way to get my 2003 S60's fan to stop running on high, even with the ignition off, is to unplug the connector on the fan shroud, so I'm guessing the fan relay has failed closed. The fan relay is on the underside of the fuse/relay board under the hood, but like you, I can't puzzle out how to get the board out. I take the TORX screws out, and there are two clips in front that are easy to undo, but It feels like it is still being held in and I don't want to force it and break the board. Did you ever figure out how to remove the fuse/relay board?
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DGM
- Posts: 459
- Joined: 23 December 2010
- Year and Model: V70 2.4i 2005
- Location: Quebec, Canada
- Been thanked: 3 times
These models have no fan relay. The cooling fan operation is controlled by the ECM through the control module located on the side of the fan shroud. When the fan is continuously on, the control module is defective. The fan assembly must be replaced.SnowOwl wrote:Hi DNA16=
I hope you got your problem sorted out. The only way to get my 2003 S60's fan to stop running on high, even with the ignition off, is to unplug the connector on the fan shroud, so I'm guessing the fan relay has failed closed.
The following thread will answer your questions.
https://www.matthewsvolvosite.com/forums ... =9&t=50104
V70 2005 2.4i 195,000km, sold
S70 1998 T5 355,000km, sold
960 1994 80,000km, sold
760 1990 Turbo 265,000km, sold
S70 1998 T5 355,000km, sold
960 1994 80,000km, sold
760 1990 Turbo 265,000km, sold
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