fj40 carb cooling fan...do you run yours?

[Coolerman]

That's for the later sensor that is normally connected to ground. The earlier sensor sits between 12v and the timer/relay circuit. I suppose the sensors could still have the same specs. We'll see. I found another sensor, the later style, in my stash.

Yes, FastEddy, I had only looked at the later sensors and just now looked at the schematics for the late 76 early 77 and sure enough the temp sensor is just a thermo snap switch, not a NTC resistance sensor. That explains why my fan controller did not work! I had assumed it required the variable sensor to ground, not a themo snap switch inline with the +12V. When I get a chance I will test my controller again using that new knowledge.

The test in oil though is still a valid test. Instead of a changing resistance you will have infinite resistance cold, then zero resistance when it reaches its rated temp.

 

[x463]

Recent FJ40 owner - bought the truck from the owner since 1983. The PO went through a lot of trouble to find a working fan controller - or at least we thought it was a working fan controller. The problem is that there seems to be a parasitic drain on the battery. When unplugged the drain stops. It's cold in Chicago so not that big of a deal currently - but I'd like to get it working. Does anybody have a guess what on the board could be causing the drain? I looked over both sides of the board and I don't see anything obviously wrong. I have 4 spares that came with the truck - this one definitively looks like the best of the bunch. Some of the others have the fried pair of diodes on the corner of the board mentioned in other posts. I can at least cannibalize those for components if I knew what was wrong.

I'd like to get this working but also found what @GA Architect did in this POST. I did something similar for a boat to turn off accessories that were often left on - only addition would be the thermosensor and a switch off vs. on relay. I got those relays from www.amperite.com - very easy to deal with.

The modern replacement by @unixman is also very interesting in this POST but probably beyond my capabilities.

Thanks!

 

[algeeba]

Last spring I decided to re-install my original '78 controller and found that it also caused a parasitic draw. My alternator could not keep up with the draw, the fan coming on and driving about 20 miles total back & forth to work 4 days out of the week. Never noticed a parasitic draw about 20 yrs. ago when I removed my fan and controller but, then again, I was less experienced back then in my early 20s.

Those two corner resistors were toast and I replaced them with no change in parasitic draw. I also found four bad transistors, replaced them and no change in draw. Maybe the large capacitor was bad, I don't know. The fan would come one when hot and turn off within 30 minutes so the timer was working correctly.

With no solution, I installed an adjustable temperature unit for fans that I had lying around. Wired this sensor along with a relay so that the fan would not come on when the ignition was off but would allow the fan to come on with the ignition off at my "pre-determined" temperature.

http://www.amazon.com/Hayden-Automo..._UL160_SR160,160_&refRID=1588366512EAS74Z2X40

 

[x463]

Glad to know I'm not the only one with a "working" fan controller....yet a parasitic drain. I'd like to get this one working if anybody knows what the problem is with the board. The fan controller is another option as well. Thanks.

 

[Richline]

Recently bought a 78 Fj55 from Canada and had it shipped to Texas. Poor old Pig probably never saw over 80 F where it came from. It has no carb fan currently and I'm having vapor lock issues. Glad I found this thread. I'm going to start with an aftermarket solution and then look for the correct original parts.

 

[overton]

Is there a thread somewhere that covers troubleshooting and repair for a non working FJ40 carb cooling fan?

 

[N919HJ]

Yes, it involves pulling the circuit board near the left corner of the firewall and re-soldering the connections. The tend to crack over time. Just like the second gen. tacoma outside air temp circuit board. If I remember correctly, it was real easy. Let me look around to see if I can find the thread.

 

[N919HJ]

Post #87 in this thread is what worked for me.

 

[billmc]

Your sensor is probably hanging somewhere not touching the header. When I installed my header I had to bend and modify the mount bracket to get it to contact the header flange. My carb fan kicks on every time I turn off the 40, even in Winter. On 100 degree days my truck has zero issues with restarts.

Nevermind. I didn't check to see how old or long this thread is.
[By design it shouldn't be touching the header. It just reads under-hood temps after shut off.]

 

[tomcrusr]

I was doing some other work on my 1982 FJ40 and noticed the fan (1st pic), and said to myself: "Self? What is that thing for? Never heard it run...or maybe I did when I first bought the truck, but not for a very long time." Next thing I know most of yesterday disappeared into the rat hole of my repair manuals and online research, not the least of which is reading this thread. But I must say I am a bit confused, or not...most of the info is about older vehicles. My fan is attached to the fender on the drivers side. When I disconnect it and hook up to 12V directly it runs fine. It appears to be sucking air in from outside and blowing on/towards carburetor and intake manifold.

The sensor appears to be mounted to a bracket that is then mounted under the intake manifold (2nd pic). I disconnected it's connector, one wire, and tried putting an ohm meter between the sensor and the engine ground. It is reading OL (open circuit, infinite resistance). I tried blowing a heat gun on it but my heat gun isn't capable of getting it very hot. I assume that I should see some resistance as the temp gets up towards 195-200 degrees, yes? I don't really want to dismount the sensor from the manifold as it looks nice and comfortable there in it's years of corrosion. I will do that if necessary but wondering if someone has an idea how to test it in place. Or perhaps I should just move on and check other components?

Which brings me to the next thing. The control box and the yellow-taped fuse holder some have talked about in the thread, I think are behind my gauge cluster. I am not as spry as I used to be so actually getting up in there is difficult so I removed the gauge cluster (2 screws, easy), and I see what I think is that controller inside a case, and the yellow tape (3rd pic). This is looking through gauge cluster hole.

Should I unwrap the fuse and check it next? If that is good, what is the next step?
Thanks,
-Tom

 

[tomcrusr]

PS: My 1980 service manual has this diagram showing relay locations (pic 1). In my 1982 truck though they definitely are not according to this diagram. Some are there, but there is nearly nothing on the passenger side and I don't see all these on the drivers side either.

The schematic below shows the circuit (in red) presumably...

 

[imyahucklbrry]

@tomcrusr
I have an ‘82 also..... my setup has worked fine until ——— it didn’t
I can’t stand not being able to figure out why but have thrown in the towel for now and just wired up a simple rocker switch to the blower for when I don’t want it to run a full 30 minutes...
FWIW... you can still get that relay from Toyota, which I did. I also sourced the temp sensor under the carb and another control box.... still not functioning as it was designed. You may get lucky with the fuse being the issue... It’s a PITA to get to but that’s where I’d start!
Good luck

 

[imyahucklbrry]

I have an ‘82 also..... my setup has worked fine until ——— it didn’t
I can’t stand not being able to figure out why but have thrown in the towel for now and just wired up a simple rocker switch to the blower for when I don’t want it to run a full 30 minutes...
FWIW... you can still get that relay from Toyota, which I did. I also sourced the temp sensor under the carb and another control box.... still not functioning as it was designed. You may get lucky with the fuse being the issue... It’s a PITA to get to but that’s where I’d start!
Good luck

Relay part#. Toyota Part No.:90987-02004-83

 

[tomcrusr]

@tomcrusr
I have an ‘82 also..... my setup has worked fine until ——— it didn’t
I can’t stand not being able to figure out why but have thrown in the towel for now and just wired up a simple rocker switch to the blower for when I don’t want it to run a full 30 minutes...
FWIW... you can still get that relay from Toyota, which I did. I also sourced the temp sensor under the carb and another control box.... still not functioning as it was designed. You may get lucky with the fuse being the issue... It’s a PITA to get to but that’s where I’d start!
Good luck

Thanks, Where did you get the temp sensor and control box? Also, I am assuming you checked/replaced the fuse (under the yellow tape) as well?
-Tom

 

[TheHardWay]

Unwrap that yellow tape and replace the fuse. 5 amp I believe. That's what I did and mine works like new. EASY FIX

 

[imyahucklbrry]

Thanks, Where did you get the temp sensor and control box? Also, I am assuming you checked/replaced the fuse (under the yellow tape) as well?
-Tom

Yes, I checked the fuse first..... the temp sensor (OEM) is difficult to source - I found a mudd member that was parting out a 2F engine for one - the control box I found on eBay
*If you ground your fan after you shut off the ignition, it should blow for approximately 20-30 minutes.... possibly meaning your control box is Ok
Since my fan blows after engine shut off, I just wired a cut-off switch...... On hot days, the fan does help!

 

[imyahucklbrry]

Unwrap that yellow tape and replace the fuse. 5 amp I believe. That's what I did and mine works like new. EASY FIX

Some guys are just LUCKY!

 

[TheHardWay]

Some guys are just LUCKY!

Best part is how well it works. Before the fuse replacement, I'd have to floor the gas pedal and crank until it finally started. Now I just turn the key and VAVOOM

 

[iptman]

I have a 77 California spec which has the big carb cooling fan in the front corner of the engine bay. My fan used to work when I had the thermal reactor manifold but since swapping to the fed spec manifold the fan never kicks on. When troubleshooting it the other day I just used a heat gun and a cheap HF IR/laser thermometer and heated up the sensor over 200 degrees and shut off the truck and sure enough the fan turned on. Took all of 5 minutes and I didnt have to unplug anything.

 

[tomcrusr]

Some guys are just LUCKY!

See blown fuse pic below. Replaced fuse, drove home, shut off engine, fan runs! Set timer on my phone. At 10 seconds before 20 minutes fan shut off. I won the lottery

Does make me wonder why it blew in the first place, but I’ll take what I can get for now...
-Tom