Still dealing with this intermittent problem but not done anything yet.


It almost has to be the ignition switch correct? That's the only way the fans can get power to them right?

 

I'm not exactly sure if the ignition switch is a sealed unit or not. If it wasn't, then any water/debris could effect the contact points inside the switch. The switch would be located at the end/bottom of the ignition key tumbler and should be attached in some way via screws. You would have to look up in a service manual on what it would take to replace it.

A quick visit to RockAuto.com shows that the switch is sealed.
https://www.rockauto.com/en/catalog...000,rav4,2.0l+l4,1364699,electrical-switch+&+relay,ignition+starter+switch,4700

I found this reference that might help you make yer repair.
https://itstillruns.com/rav4-ignition-switch-removal-7714829.html

I believe this is the OEM part number.
84450
SWITCH ASSY, IGNITION OR STARTER
84450-12200
STEERING CORUMN
1
$103.47

Youtube video on a 4Runner ignition switch replacement. Yer RAV4 should be very similar. You should be able to use the video to inspect the switch before you buy a replacement switch.

 

-- See attached electrical diagram of the cooling fan circuit. First and foremost, I suggest checking the "e/g main relay" in the engine bay fuse box, on the driver's side in the engine bay (see the component locations attachment as needed). From the attached electrical diagram, the ignition switch only powers the e/g main relay's coil. When the relay's coil is energized, the relay's switch closes and provides power (from the "hot at all times" 100 amp alt fuse) to the radiator fan et cetera. Next time the fan is stuck on, tap on this relay, or even pry it out completely. If the fan goes off, consider replacing this relay. From the electrical diagrams, I think turning on the wiper (or turn signals?) or cycling the ignition switch could change the current going to the e/g main relay's coil just enough to perhaps jar the relay into the correct position.

-- I do not think either the A/C water temperature switch or the A/C single pressure switch could fail so as to cause the fans to stay on. But if you want to check them, see the attachment for their locations. (Note for newbies: On hot days, the radiator fan and/or HVAC condenser fan may stay on after shutting off the engine for a certain period of time, to cool the engine down et cetera. Whether a failed a/c water temperature switch would cause the other symptoms the OP lists is not clear to me.)

-- I also do not think the three fan relays in the second engine bay relay box are the problem, unless you have a multiple failure of relays (which is possible but not likely). But if you want to check these relays, they are located on the driver's side of the engine bay, just aft of the driver's side headlight. For exact location of the relays, see "engine room R/B" in Fig. 1 in the attachment.

-- If you have a salvage yard nearby, maybe pick up a second-hand e/g main relay and see if it fixes this.

 

Thanks to both of you for such a detailed response, especially on Xmas eve!


The next time it happens (and I'm aware of it - it just decides to randomly come on and this is my daughter's vehicle) I'll try the EG relay, I may have a salvage yard spare (or swap from one of my other Toyos). This makes sense as fiddling with the wipers etc has stopped it before. Plus this is simpler than replacing the ignition switch, which was the only way I could figure out that the "turned off" vehicle would arbitrarily get power to the fans. And I need to see if it is both fans or just one - and which one. Seems like it was both. Frustrating part is it happens only every couple months but lately has done it twice.


Merry Christmas and thanks again.

 

For what it is worth: The diagram I attached shows the various relays with their respective switch positions when the ignition is off (or key out). With the ignition off, and the e/g main relay stuck in the wrong position (meaning the position opposite to what is shown in the diagram), the diagram seems to indicate that both the radiator fan and A/C condenser fan come on in parallel (high speed). Other configurations (and with no failures of any part) put the fans in series (low speed).

For the archives, the following thread seems to have some good chatter on this circuit for a second generation Rav: https://www.rav4world.com/forums/85...forums/85-4-1-faults-fixes/73067-electric-cooling-radiator-fans-all-time-2.html . The circuit sounds very similar to the first generation's.

The Toyota OEM part number for the e/g main relay is 90987-04002. It currently sells for about $16 + shipping costs at online dealers, and under $10 for an aftermarket version on eBay. Autozone, Napa and the like might have it as well. It is called the 'main blower a/c cooler HVAC relay' and similar at some sites. Of course, if you try a local shop, you can bring the old relay with you and match it up.

Hopefully this relay failed and is the only problem. Merry Christmas to all.

 

I must say I definitely do appreciate your in-depth answers, time and attention to this. Very uncommon of forums (except for a few specific ones I frequent).


I found a similar EG relay and swapped. I'll see what happens now although it may take a while for this intermittent problem to rear it's ugly head again.


Many thanks,