OEM Carb Fan Controller Replacement

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I'm guessing that all of your controllers are Federal as opposed to California, which is what you want unless you actually have an FJ40 with the thermoreactor manifold still installed. A CA controller won't necessarily function as intended with other manifolds.

I'll measure the current on my OEM fan wire to see if I have a slow but negligible drain as well. It should be very low (~35uA) with <1V through the thermistor at 25C or zero if I remember correctly.
 
unixman said:
I'm guessing that all of your controllers are Federal as opposed to California, which is what you want unless you actually have an FJ40 with the thermoreactor manifold still installed. A CA controller won't necessarily function as intended with other manifolds.

I'll measure the current on my OEM fan wire to see if I have a slow but negligible drain as well. It should be very low (~35uA) with <1V through the thermistor at 25C or zero if I remember correctly.
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Federal truck - not Cali. No thermoreactor.

Appreciate the reading - be interested to see the results.

Just got back from the first drive with the seemingly functional "no click" fan controller that was in the spares box. I drove 5 city miles and it's about 33 degrees out. Fan kicked on when I parked and stayed on at least 10 minutes. Very little heat trickling out of the heater and the gauge was just starting to register. Guess I know why this one was in the spare pool. I'll put the original back in and test again. Could be a sensor problem but I kinda doubt it.
 
x, for the one in the last test, did you reflow the solder on the connector? You could just be getting a higher resistance on the sensor pin.

For any one I was going to test, I'd reflow the solder wherever I could get to.
 
I have a 77 CA spec with the TR and no cooling fan. The space where the 78 carb fan goes I have the wiper fluid reservoir. I think the 77 CA had the huge fan in the front left corner of the engine bay but I don't have that either. Where would the controller be for the CA fan?
 
Fast Eddy said:
What makes you think there's a CA-specific version? All this stuff is external to the manifold and the TR would just take more time to cool down. I believe they are the same, which jives to Coolerman's part number list.
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The Toyota Service Specifications for the cooling fan state that the fan should start when the temp is 100ºC Federal or 120ºC Calif. The fan should stop when the temp is below 85ºC Federal or 105ºC Calif. With different start and stop thresholds and both using the same thermistor, the controllers would be different. x463's 85927-60020 is for a '78 2F but my 85927-60030 is also for a '78 2F and '78 doesn't appear to be a transition point for fan controllers. (SOR sells both Federal and CA '78 controllers.) If that is indeed true (and I've been wrong about a lot of things), then anyone with a CA-spec controller won't be getting the designed benefit of the fan unless they're using the original 'reactor exhaust manifold. With a federal manifold or aftermarket header and the original CA controller, their fan won't come on until 120ºC and shut off prematurely at 105ºC, a completely different operating window. Everything "works," but not the way you would want it to.

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Fast Eddy said:
x, for the one in the last test, did you reflow the solder on the connector? You could just be getting a higher resistance on the sensor pin.

For any one I was going to test, I'd reflow the solder wherever I could get to.
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I was going to....but after messing around with the spare with the two fried diodes I decided these things are too fragile. I looked at each soldered terminal very closely and didn't see anything.

Latest update...I tried the controller that was unplugged in my truck at purchase (the one that clicks). Fan is coming on in the same cold temperatures as the "spare" that doesn't click.

Now I'm thinking it's might be the sensor. I was going to replace it...until I saw the price. Expensive gizmos. I'll pull it sometime and double check on the stove.

Going back to the non-clicking controller to at least check for any battery drain.

@unixman's controller says '78 but the part number is for the '79 range @Coolerman posted earlier. Do you know when your truck was built? Mine was Dec of 78...possible the changeover happend after my truck and before yours. I can email you a hi-res photo of my controllers if you want to compare for any differences.
 
I never thought anything about my cooling fan until seeing this thread. Excellent thread by the way... I will say however this is way above my pay grade and I think I will have to go back and read it again... :)

That said, my fan comes as soon as I turn my ignition off even if I only put my key into the ignition and turned the radio on and did not start the vehicle. It does run for about 20 mins and then shuts off. I take it that from the sound of it through this thread that is not normal? Is that right? I have a 1980 40. Is there something I can check / look at to see if I have an issue. The engine is clearly cold and could not be of 120 degrees or anything as it has not run in a couple days etc.

The fan does not come on with the key in in the on position, but as soon as the key is turned off, it runs for the 20 mins and turns off.

Sorry to step into your thread here...
 
DTSkyCop said:
I never thought anything about my cooling fan until seeing this thread. Excellent thread by the way... I will say however this is way above my pay grade and I think I will have to go back and read it again... :)

That said, my fan comes as soon as I turn my ignition off even if I only put my key into the ignition and turned the radio on and did not start the vehicle. It does run for about 20 mins and then shuts off. I take it that from the sound of it through this thread that is not normal? Is that right? I have a 1980 40. Is there something I can check / look at to see if I have an issue. The engine is clearly cold and could not be of 120 degrees or anything as it has not run in a couple days etc.

The fan does not come on with the key in in the on position, but as soon as the key is turned off, it runs for the 20 mins and turns off.

Sorry to step into your thread here...
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This may be a long shot, but you may have a bad carb cooling fan thermo sensor? It is located on the intake mani. Or, the thermo sensor wire is grounding out causing the carb fan system to activate when the key is turned......just something to check.
 
Thank you GA Architect, I never thought about it honestly until reading this. Actually never really knew why it would be necessary for the fan to stay on for about 20 mins as I described earlier when the vehicle never ran. NOW I KNOW there is a possible issue. I am a NEWER 40 owner having only owned mine now for approximately 1 1/2 years now... I am learning more and more here on Mud and love reading the Threads (like this) as I enjoy my "retirement" purchased play vehicle.

Thank you again for the information, now I will look into the Thermo Sensor and see what is up! :)
 
DTSkyCop said:
Thank you GA Architect, I never thought about it honestly until reading this. Actually never really knew why it would be necessary for the fan to stay on for about 20 mins as I described earlier when the vehicle never ran. NOW I KNOW there is a possible issue. I am a NEWER 40 owner having only owned mine now for approximately 1 1/2 years now... I am learning more and more here on Mud and love reading the Threads (like this) as I enjoy my "retirement" purchased play vehicle.

Thank you again for the information, now I will look into the Thermo Sensor and see what is up! :)
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And when you go investigate this, post up some photos.....everyone likes photos. :hillbilly:
 
GA Architect said:
And when you go investigate this, post up some photos.....everyone likes photos. :hillbilly:
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I most definitely will!!! Thanks again for the information... :clap::cheers::beer:
 
SOR does list the CA of FED spec controllers but does not list the OEM part number. I got my list from the online parts catalogs, but they did not list the CA or FED spec. A bit of time researching through the EPC should find a complete list of controllers, part numbers ans whether they are FED or CA spec. I can't get the EPC installed on my Windows 10 box for whatever reason or I would do it...

I have the 60010 controller which is the small simple one...
 
iptman said:
I have a 77 CA spec with the TR and no cooling fan. The space where the 78 carb fan goes I have the wiper fluid reservoir. I think the 77 CA had the huge fan in the front left corner of the engine bay but I don't have that either. Where would the controller be for the CA fan?
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Mine is from an FJ55, with a custom bracket. The FJ40 version is the same fan and lives in the same place but it mounts to the fender. I have a piece of rubber tubing to extend the intake down to the right of the fan so crap doesn't get blown into it by the someday-to-be-working carb fan.

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unixman said:
I believe the controller is in the same location as the '78, passenger footwell behind the heat duct. Do you not have hard start issues with the TR after the engine is hot?
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Yea, same spot. My '76 has all the parts to get it working, but it doesn't work yet.

I do have some minor issues with hot starts, and I'd like to get the fan working.

Not sure about '77, but in '76 the sensor is above the valve cover, towards the back, instead of mounted to the exhaust manifold, as per this diagram. It also clearly shows that the 'sensor' is a binary switch rather than a variable resistor. This is what I determined experimentally as well in a pan of hot water.

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The drop-in replacement has worked fine for several months and I built a second prototype to address some items I wanted, in particular a temp readout without having to connect a serial data wire to a laptop. The second build has an LED display that indicates the thermistor temp when the engine is on and alternates between temp and fan timer when the fan is running. If the display reminds you of an old HP calculator, it’s because they’re from HP and apparently remain unchanged since the 70s. This required a dedicated 7-segment driver or micro-controller (uC) with more pins and I opted for a 28-pin Atmega328.

I added a DIP switch to allow four user-selectable modes (e.g., aftermarket thermistor with different NTC curve, different temp thresholds for different years, for using a 76/77 thermal "klixon" switch rather than a thermistor). There is a trimpot rather than a fixed resistor in the voltage divider so if the thermistor is not where it is designed to be, you can slew the NTC curve to correct for the change. In other words, if you measure the temp near the carb with a thermocouple to be 100C but the thermistor at its location is only at 90C, you could adjust the controller to compensate for the difference.

The relay was replaced with a power MOSFET. This allows the fan to run at speeds less than 100% if desired. It doesn’t generate much heat but I over-engineered it to dissipate the heat through the ground plane of the PCB anyway.

For troubleshooting, the green fan LED is powered by the fan wire so if you have a green LED on and the fan isn’t running, you know it’s a problem with the fan or fan wiring. If you don’t have a red LED when the key is switched on, the connection from the ignition to the controller is bad. If the red LED goes out (board shuts off) when the engine is hot (>100C) and the key is switched off, then the 12V connection from the battery is bad. If the LED display shows four dashes, the thermistor or its wire is the problem. (If the sensor is missing but the wire is grounded as a workaround, the controller reads a very low resistance corresponding to a temp over 999.9C, too large to display. If the wire is not connected, the resistance will be too high corresponding to a temp below 0C, which cannot be displayed.)

There’s still a two-pin data connection where you can read from the EEPROM how long the fan ran and the highest sensor temp the previous time the engine was shut off and there’s a six-pin in-system programmer so the uC can be reprogrammed without removing it from the board.

I think I’m finished with this project for now. Thoughts and constructive criticism are welcome. Although I like the inherent troubleshooting abilities of the second board, I appreciate the simplicity of the first. One thing I have yet to do is put my sensor on the stove and create a detailed lookup-table style NTC graph to compare with the theoretical Steinhart-Hart calculations I’m using. Someday…

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Wow, even with Google translate I felt like a third grader in a calc class. Phenomenal work. Are you marketing these? What does one use for the sensor in the engine compartment? I'd like to get my fan working by summer, what with global warming and stuff.

:clap:
 
myquestoyota said:
Are you marketing these? What does one use for the sensor in the engine compartment? I'd like to get my fan working by summer, what with global warming and stuff.
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I hadn't given much thought to selling any yet, but I have the parts for a couple of each design. Not even sure what it cost me to build. Preferably you use the OEM sensor and bracket depending on the year. Before late '77, Toyota used a thermal switch that doesn't appear to be prohibitively expensive to find used. On the other hand, the later thermal sensor is crazy expensive used. I never conducted a thorough search for a suitable replacement for the sensor. I started looking for a similar sensor with the same thread size and pitch to use with the original bracket, but didn't get far. If there was a good option for a replacement I could program the NTC curve.
 
I'd be interested in one....no frills version is more then sufficient. The idea to be able to utilize a cheaper sensor is a great one. I still need to check mine - going to try with an infrared/laser point&shoot temp gauge before removing. Hopefully this week - truck has been down for several days for DIY electric power steering install.
 
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