Weird Camry Radiator Fan Wiring Dealy

Good Evening To You All,

My $225 1989 Toyota Camry 4-cylinder 5-speed auction find has both fans running all the time.

I checked the following:

Both relays show continuity across the switch side even when pulled out but so does every other Toyota relay I tested (????). The fan temp sender is right on spec (2.2 k-ohm @ 68 degrees F). Fuse box not tampered with. Voltage present at the relay coil side all the time. The grounds for these relays are in different places. Wiring to both fans intact.

I need to get this car smogged soon. I would like to do it with the fan circuitry set up properly. I suppose I can do it by pulling the fuse for the AC fan. Temps run normal then. However, it takes a while for the car to warm up.

I'm pretty good with auto electrics but this one has me scratching my head.

I have the same problem with my wifes 98 camry. Eventually the fan motor got really loud and broke. I just made it so I can run swift/sprint fans in it because I have about a dozen of them and the toyota ones were expensive.

I dug through the fan control circuit on my 88 Rolla once, as part of getting the AC system going after the MegaSquirted 20v swap. I would imagine that your 89 Camry is similar. My conclusion was that it is a colossal cluster berkeley. It is like Germans designed it or something. I am surprised it ever worked at all, and the fact that it still works after 20 years just amazes me. Anyway, if it works the same way, there should be a water temp switch, not a temp sender. A sender would imply a control computer somewhere, which there might be, or it might be controlled by the EFI computer (as is done with many other manufacturers today), but that would be different than what the Rolla 4AG did. If the switch isn't stuck, then the system will also turn the fan(s) on if the AC is enganged or if it thinks the AC is engaged. If there is a fan control module, then that might be suspect.

If you find me the actual schematic for your car, I'll diagnose it better.

You're right about the cluster berkeley. Turns out there are no less than three devices measuring water temp. One goes to the ECU (the one I checked), the thermo-time switch for the cold-start injector, and the fan switch located at the thermostat housing. I confused the ECU sensor with the fan switch so I'm going to test for cold continuity. I'm trying to finish a Nissan GA 16i (1989 Sentra) rebuild for a customer so I may not have time to check it today. When I do, I'll post it.

Yes, your Corolla is similar. The relays pertaining to the cooling system are the same.

As for the schematic, I went to the central branch of the LA Public Library where they have the shop manuals for almost every car ever built (Including TWO Borgward manuals) and copied the pertinent parts. However, the color codes don't match what I'm looking at for the most part, even though I'm looking specifically at a manual for an '89. If I find a schematic online, I'll post.

Thanks for responding.

more than likely, theres one for the gauge, one switch to tell the ecu when to switch from warmup to normal temp running, and one that tells the fan when to kick on. on my 89 ford probe, it was this way. if the fan temp switch is unplugged or goes wonky, the fan runs all the time, this may be the problem you've got

My Celica did this when the temp sensor in the water neck went bad. I have a rev2 5sfe vs your 3sfe, but i think it should be similar enough to be worth checking out.

93celicaGT2 wrote: My Celica did this when the temp sensor in the water neck went bad. I have a rev2 5sfe vs your 3sfe, but i think it should be similar enough to be worth checking out.

Very similar. My wife's '97 has the 5-SFE.

I forgot the temp gauge sender so thanks for reminding me. So there are at least FOUR devices measuring water temp in my '89. Why can't there be just one? You might as well run it all through the ECU anyway. The ECU can interpret the data and switch stuff on and off when necessary. If the sensor/switch fails, the ECU can go into "limp home" mode and throw a code.

To be real honest... i ended up just putting a rocker switch in my car to control the fan. The radiator on my car is HUGE, and unless it's in the 90s and i'm idling for a long period of time, there's no reason for the fan to be on.

If the sensor in the neck is bad, shoot me an email, i have 2-3 extras for the 5sfe, and i suspect it's the same part.

If you need a wiring diagram let me know, I have a few FSM's for the camry (have 88-89, maybe 87).

I also have an 87 camry with no spark closely approaching the point of diminishing returns on the time/$ to get the pos running again.

I HATE electrical problems on these cars. Had a light control computer go out, about went mad testing things.

Hope you get it fixed, I always liked the low grip and neutral handling.

Are you all implying that Toyota has design problems? Shocking...

So they are all E36 M3?

E-

Hey daytonaer, you forgot to mention the squishy suspension too. I bought the thing for nothing and only invested a couple hundred for brakes and a bunch of boneyard stuff so I don't feel bad.

Meanwhile, nothing is ever simple. I started the car dead cold and yanked the wire off the fan switch. The fans still run. In theory, that should kill the fans but no. Still looking for a wiring diagram online. Otherwise I need to go back to the library and drop more quarters into the copy machine.

alfadriver wrote: Are you all implying that Toyota has design problems? Shocking... So they are all E36 M3? E-

LOLZ

Jerry From LA wrote: Hey daytonaer, you forgot to mention the squishy suspension too. I bought the thing for nothing and only invested a couple hundred for brakes and a bunch of boneyard stuff so I don't feel bad. Meanwhile, nothing is ever simple. I started the car dead cold and yanked the wire off the fan switch. The fans still run. In theory, that should kill the fans but no. Still looking for a wiring diagram online. Otherwise I need to go back to the library and drop more quarters into the copy machine.

the system is supposed to fail safe, so if the switch goes bad, the fan runs rather than not, and keeps things from overheating. see what happens if you ground the switch wire

Strizzo wrote: the system is supposed to fail safe, so if the switch goes bad, the fan runs rather than not, and keeps things from overheating. see what happens if you ground the switch wire

I'll try anything at this point. The only way to shut off the fans (other than disconnecting them or pulling the fuse) is to yank the relays.

the fan switch opens at approximately 195. it then cuts the ground to the fan relay, which closes and turns on the fan. the second (main) relay keeps the system from operating with the key off.

in summary: fan main relay closed with key on. fan relay coil + charged with main relay closed fan relay open with fan switch closed >195f

Yep that's a failed coolant temp sensor (for the fan).

My AE92 has 2 temp sensors, one for the fan and one for the gauge.

My AE92 has 4 temp sensors: Fan, guage, cylinder head for EFI, intake air temp.

If you can post your email address I can send you the wiring diagram and an explanation on how it is supposed to work.

The tough part with most of these fans is that they are two speed. For low speed they are wired in series with current going from one fan to the other and then to ground. High speed the fans are parallel where each is fed +B and then straight to ground.

I need to look at this one to see if it is exactly like the above but most of them are.

Scott

Scott_H wrote: If you can post your email address I can send you the wiring diagram and an explanation on how it is supposed to work. The tough part with most of these fans is that they are two speed. For low speed they are wired in series with current going from one fan to the other and then to ground. High speed the fans are parallel where each is fed +B and then straight to ground. I need to look at this one to see if it is exactly like the above but most of them are. Scott

Thanks for the offer, Scott. I'll PM you with my email address so you can send me your stuff. I haven't been able to look at the car or sign into the board the last few days so I'll try Strizzo's idea of grounding the fan switch wire to see if the fan goes off. If it does, we may have a winner.

Checked the continuity of the fan switch at dead cold. The circuit was made which, according to the above posts, means everything is as it should be. If I read correctly, the fan switch turns OFF at 195 degrees which kills power to the relay and allows current to reach the fan motor. So a defective fan switch would leave an open circuit when it's dead cold.

Than also means grounding the fan switch wire had no effect whatsoever. The fans still run all the time.

I checked for some crude bypass somewhere in the circuit and found none. Judging by the level of stupidity found elsewhere in the car, any attempt to bypass the fan switches should be obvious.

This one is a real head scratcher.

I wish i could actually look at it....

I would honestly make a trip the junkyard at this point and just pick up a couple copies of all the sensors and go to town replacing them til they work. I wouldn't consider what you have a common problem. Most of these sensors that i get from junkyards for the Toyota "S" series motors DO work.

Well, I'm going to the boneyard now to replace a broken TVS switch so I can make my EGR and vapor purge systems kosher for the visual inspection.

AH-nold just changed the law so I cannot renew my temporary registration without failing a smog test first. So my hope is to get the car to pass and get my real plates which are already paid for.

I would get some boneyard replacement stuff if I thought it would work. I bring my VOM to the boneyard and all the relays and sensors test like the ones in my car.