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This is my daughter's 2000 4x4 with 225K on it, second owner.

I'm dealing with an elusive electrical issue that is wearing me out. Mainly because it comes and goes. Fix what I think might be the issue and then a couple months later it pops up again.

Started more than a year ago. Dead battery. Charged and did fine. Did this several times until one day walked by it and the coolant fan was running... So I swapped out the sending unit not knowing what else to do. Couple months later same thing. Pulling fuses/relays will turn it off - but then the inside heater fan comes on. Sometimes the odo is lit and the oil light glows faintly. I'll fiddle with things and it goes away only to rear it's ugly head again months later.

I've cleaned the grounds. Pulled (then swapped, then replaced) all the fuses and relays I can find (2 boxes), wiggled wires but can't track it down.

Electricity is my weak spot. I can rebuild motors and add accessory etc but electrons confound me in general.

This has got to be a short right? Could it be in the ignition/key switch? Happens even with the key out, hot/cold, day/night, wet/dry... Today I'm adding a battery cutoff just so my daughter doesn't get stranded somewhere but this is definately not the cure.

Any ideas?

Thanks,
 

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IDK, abut I'd suspect (too) something in steering column.

I'm not great with electrical either, but one thing I learned on these RAV4.1s is to add a big, second ground wire from the negative battery terminal directly to the engine. The OE ground strap is tiny, and corrodes, thus making charging, starting, etc. worse, and stresses other electrical parts.
 

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Discussion Starter #3
You know, when I was cleaning the grounds I was thinking the exact same thing. I added additional ground straps to my 1st Gen Cummins, which was minimal to begin with too. Worth a try.
Thanks,
 

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Did this several times until one day walked by it and the coolant fan was running...
Was the ignition key fully removed when you saw the cooling fans (next to the radiator) running? Were both cooling fans (next to the radiator) running? I am trying to process all the gremlins but think the cooling fan circuit might be a starting point for where to start checking for grounds or possibly open circuits. An open circuit (in the wiring to the cooling fans' ECT switch) would cause both cooling fans to come on, but the relays have to be in the right position, or some other failure in the wiring has to be present, for the fans to be getting electrical power without the key in the ignition.

Does this Rav4 have a remote starter?

By "sending unit," do you mean the cooling fans' ECT switch?
 

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Discussion Starter #5
Correct, the key doesn't have to be in the ignition for things to go haywire. No remote starter. I replaced the temp sending unit in the rad,

I can't remember if removing the cooling fan relay makes the phantom dash lights go out or not, seems like not.

Yesterday, after installing the battery terminal shut off and another ground the fan (drivers side) came on when I hooked it all back up. Pulling the mini 10amp fuse under the dash shut it off. It was labeled AM1 but not sure what all it does. Banging the relay box also made the fan go off until I turned the battery cut off back off and then on again so I guess there must be a short in or under it huh? Or did banging it shake a relay?

Thanks for your time and thoughts on this.
 

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In the wiring diagrams, the driver's side fan is known as the "radiator fan." Here is the wiring diagram for the 1999 Rav4 (which I believe is the same as the 2000):

With a multimeter, there are a lot of tests you can do. Hopefully the wiring diagram will help. One test is that, next time the driver's side fan comes on, unplug it carefully, and check the voltage across the plug's two terminals. If it is less than 12 volts, this would say something.

Other thoughts:
For the radiator fan to turn on, the E/G main relay switch must be shut and either:
(1) the Fan relay #1 switch must be shut.
or
(2) the Fan relay #2 switch and the Fan relay #3 switch must be shut.
or
(3) somehow the blk/red wire going to one side of the radiator fan motor is getting 12 volts (maybe less?), possible through a fray in the wire.

If (2) above is happening, then the passenger side fan would also be running. But it is not.

Since banging the relay box yielded some results, I would suspect that one or more relays may be bad. (I do not like assuming a double failure has occurred. Double failures are uncommon. But just to keep diagnosing, I would consider replacing the E/G main relay and Fan relay #1. The salvage yard may be your friend here. Also new relays are not too expensive. Take the two relays out of the engine bay driver's side relay box and see how much Radio Shack charges for them.)

Alternatively, the banging may simply have caused a frayed wire to stop touching a wire with 12 volts on it.

I cannot rule out a failure of either the cooling fan ECT (water temperature) switch or the ignition switch right now, either. But again, this supposes a double failure. A frayed wire somewhere somehow getting 12 volts seems more likely.

I am contemplating the cabin blower et cetera coming on as well. In extreme cases, I know mice can chew on wires and wreak havoc. But concluding this is just a cop-out at this point. These Rav4s are old. Let's see what voltage you get at the driver's side fan's plug and how the relays check out.
 

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Discussion Starter #7
This is the kind of of info I'm needing. I was looking at the FSM schematic night before last while taking a break from wrenching on my KJ and I had no idea where to start...

Compounding the problem is it being my daughter's, I seldom drive it and her being 18, it is seldom home...

BUT, next time the fan is running I'll check the voltage. I'll also check and see if pulling that relay has any affect on the phantom lights in the cabin and heater blower. Seems like not but been dealing with this off & on for so long it's hard to remember. For some reason I'm thinking at one time both or either fan would come on but not sure now. That's the odd part, it can be fine for months.

I already swapped out all the relays and they "feel" tight in their sockets so your thoughts on a loose or frayed wire may be more plausible. Being second owner (bought from a friend) it is in really good shape but living on a farm we've had mice in vehicles but no evidence in this particular one - yet.

This past weekend my daughter and I swapped cars so I had a chance to mess with it - but no help. With the key off and if I turned the heater fan on I could hear a relay (maybe two?) "boink" but couldn't track it down by myself. Seemed to be coming from the drivers side firewall but all I could find there was the cruise etc. Could have been on the inside. Maybe this weekend will yield more time to troubleshoot.

Many thanks, Elle RAV4, you have been a big help.
 

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If the cabin blower comes on spontaneously, with its switch in the off position, you could also unplug it and check the voltage across its plug's two terminals.

When it comes to possible frayed wires for the above Rav4, one area that leaps out at me is the area around the a/c pushbutton toggle switch (built into the dashboard HVAC control module). The A/C pushbutton toggle switch turns on the two fans in the engine bay under certain conditions. But the A/C pushbutton toggle switch is also right next to the cabin blower variable speed switch. Since the fan (or both fans) in the engine bay has (have) turned off after a little adjustment, followed by the cabin blower mysteriously coming on, I think I might pull out the HVAC control unit and check the back of it for frayed wires. Then I would think about some checks I could do with my digital multimeter. Some clues on the electrical connectors for the HVAC control unit appear below:



Is there an aftermarket radio installed, like someone has been back there and got sloppy with, I dunno, a soldering iron? Or loosened a wire so that the wire is rubbing against something, and maybe some of its insulation got stripped?

As I am sure you can imagine, lots of possibilities. I would try to stay systematic.
 

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Discussion Starter #9
Interesting.

Radio is stock. The only non-standard thing it has is the optional anti-theft system which is either factory or dealer installed, But we've never used it, nor had the previous owner.

The heater comes on only if it was left switched on, with the key off/out. If that makes sense?

Checking the AC button & heater controls is worth a look. Never had the dash apart. I guess the fascia has to come of before the panel comes out? I'll check the FSM. Need to peek at the clock anyway as it fades in & out sometimes.

Thanks,
 

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Next time the engine bay fans come on with the key out of the ignition, here's another easy voltage check to do: Go to the fuse box near the driver's left knee. Remove the ECU-IG fuse. (The inside cover of the fuse box should identify the location of this fuse.) Check the voltage across the ECU-IG fuse holder's two terminals. If there is any meaningful voltage, then 'upstream' of this fuse, there is something providing voltage to the fuse when there should be no voltage (as long as the key is out of the ignition).

I attach my step-by-step for getting into the HVAC panel and the instrument cluster.
 

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Discussion Starter #11
Cool. Thanks.
I'll pack a voltmeter with me this weekend and see what I can find out. Probably won't act up all weekend...
 
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