Cooling fan killing my battery

spitv8 · Post by **spitv8** » 12 May 2010, 17:28

Hello
I'm new to this site although I have used it in the past for help with my 2000 V70T5.
The latest in the never ending queue of problems afflicting this car is that the radiator cooling fan is coming on seemingly for no reason.
The temperature gauge shows rock steady at 12 o'clock and the thermostat and coolant temperature sensor have been replaced with new.
After any and all journeys, or even just starting the engine and switching off again, the fan comes on after about 5-10 seconds and runs on low speed for several minutes.
This has caught me out a couple of times now with a dead battery -fortunately not away from home.
The fan control unit seems to take a signal from a violet wire to switch the fan on and off - but from looking at the wiring diagrams on this site the violet wire comes straight from the CEM (ECU).
I have seen the same problem questioned in a few places but never with a solution. The only clue was from a reply which gave the MAF unit as the culprit. I changed the MAF last year but noticed an error code relating to it when I read them the other day. Could this be the problem?
Any help or suggestions that don't involve a gallon and box of matches gratefully recieved!!

Tim

jda2000 · Post by **jda2000** » 12 May 2010, 18:26

do you have any trouble codes stored in the ECM?

Post by **jblackburn** » 12 May 2010, 18:39

I hope you mean 3 o clock not 12

Try fastening down the wire to the MAF sensor with a zip tie and see if this makes a difference.

Mine killed the battery a few times before I figured it out, but on my car the MAF sensor has nothing to do with it, but as I understand the 99-2000's use it differently.

The ECU has to feed the cooling fan relay a signal to get it to turn on...so something's gotta be telling it do that.

FCPEURO · Post by **FCPEURO** » 12 May 2010, 19:20

Have you check the fan control relay? It could be what is causing the fan to turn on and off on it's own.

spitv8 · Post by **spitv8** » 13 May 2010, 17:03

Hello again

Still a bit of a mystery. Checked the MAF today, it's clean and the connections are all good. Disconnecting made no difference, nor did removal and refitting. Checked the relay and this is working fine.
Like I said the fan is off but comes on after turning the ignition off - runs for a few minutes then turns off again.
So something is telling it to switch on, but what?
There are 5 codes which keep recurring. One is P1520 Manufacturer control, then three relating to pedal position sensor which have been there a while (another ongoing fault which I am blaming the ETM for but which precedes the fan problem) And one saying Mass Air Flow reading low.

Any clues?
Tim

icelandic · Post by **icelandic** » 13 May 2010, 17:44

Check the connector on the Coolant temperature sensor. Sometimes , during replacement, when the male side is pushed against the female side, the contacts on the female side are pushed back and make poor or no contact. You get a normal temperature reading, but the fan comes on unecessarily. Before you go and disconnect the plug, take a good look at it and try to push the two wires on the female side towards the male. You can use pliers to do it, but be careful.

Post by **1997volvo850** » 13 May 2010, 17:58

Tim,

I have an 850 GLT that is related to the v70.

Here is what my manual state:

"WARNING The coolant fan may start or continue to operate (for up to 6 minutes)
after the engine has been switched off."

There is also a "Self-Starting Fan" warning on top of where the fan is. Mine also runs after
the engine is turned off, but it is designed to do so.

The question I would ask is why would running a fan kill a healthy battery? Is your battery
in good shape? How old is it?

I guess the other question is whether your battery is getting charged by the alternator.

spitv8 · Post by **spitv8** » 14 May 2010, 16:26

Hello
Thanks for the tips folks.
I know the fan can come on after the engine has been switched off due to heat soak after a run etc, that is perfectly normal and expected. But I'm talking EVERY time, even just moving it from one side of my yard to the other with a cold engine.

To deepen the mystery this afternoon I went to start the car - battery dead. So I boosted it and set off - to my amazement for the first time in over a year I didn't have an orange warning triangle and check engine light on. A clear dash panel!! I was chuffed to bits.
Got to my destination, stopped, restarted and back to normal with triangle and check engine light - gutted.

Alternator is charging fine, battery is probably past its best but this problem is really killing it off and I'd rather solve the problem than just throw a new battery at it.

Ho hum
Tim

007 · Post by **007** » 13 Mar 2013, 09:23

FCPGroton wrote:Have you check the fan control relay? It could be what is causing the fan to turn on and off on it's own.

Hi, could someone let me know where is the engine cooling fan relay located?

Thanks.

Post by **erikv11** » 13 Mar 2013, 09:37

For the car in question, it attaches to the underside of that black plastic shroud over the radiator.

If you mean for your XC90, maybe the same place I don't know - ask over in the other forum.