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

[Engineer8000]

Those 78 fan controllers are an issue. I have fixed a bunch of those. @mattressking is correct, grounding the temperature sensor wire tricks the controller into seeing a high temperature and the fan will run about 28 - 30 minutes after shutting off the ignition. I placed a video of how to test the controller in my small business storefront, post 166.

Cape Fear Electronics

connectors

forum.ih8mud.com

 

[mattressking]

Those 78 fan controllers are an issue. I have fixed a bunch of those. @mattressking king is correct, grounding the temperature sensor wire tricks the controller into seeing a high temperature and the fan will run about 28 - 30 minutes after shutting off the ignition.

You're seeing 28-30min? That's good to know, I never timed but personal experience was around 20min. Totally semantics but good to know.

 

[Engineer8000]

The manual says 23-37 minutes, I usually see upper 20s to around 30 min. The timing is controlled by an RC time constant. I usually change out that cap with a new one, could be your cap value has decreased due to age if it has not been replaced.

 

[Goldbug]

@mattressking and @Engineer8000 Thank you both. I'll fire up the woodstove when I get home and do some more investigating out in the garage.

 

[greenEFSI]

Thanks for the help guys. A quick little jumper harness got the fan working again!

It’s blowing the paper nice and strong

 

[Ackcruisers]

I’ve read through this entire thread and have not found the specs for an aftermarket thermo switch that will work with the 1976 &1977 California Spec carb cooling fan relay 85927-60010. The CA spec relay and switch is different than later models. The later models are a resistance sensor vs. snap switch. Below is an image of the OEM switch with two wires LB and GR from harness out to the sub harness then out to switch.

As shown in the below diagram, there is a thermo “snap switch” that closes the switch to send 12v to the relay. The relay then sends 12v to the carb fan and the timer runs for approx 20 minutes only when the ignition is off.

@Engineer8000 posted a great video on this relay here.

I am looking for the temperature spec for the switch to close the circuit. I estimate it to be 170+ degrees ON (closed) so it will not run in winter.

If anyone has a good source for an automotive snap switch that will work please post it.

 

[Engineer8000]

These are the specs for the later controllers

 

[iptman]

Are you looking for documented numbers or tested numbers. I used a heat gun and a laser thermometer gun to verify and test mine. If I recall it was around 200f when my fan kicked on. Certainly not precise but I could do the test again with my FLIR camera. Its definitely high though. Since I switched to a Fed spec manifold my fan never kicked on.

 

[Ackcruisers]

Are you looking for documented numbers or tested numbers. I used a heat gun and a laser thermometer gun to verify and test mine. If I recall it was around 200f when my fan kicked on. Certainly not precise but I could do the test again with my FLIR camera. It’s definitely high though. Since I switched to a Fed spec manifold my fan never kicked on.

Thanks..I think documented numbers are good enough and can work from the information just posted by Engineer8000. What I’m really looking for is an aftermarket thermo snap switch that will work with the fan controller relay I have.

 

[Engineer8000]

https://www.amazon.com/Thermostat-Switch-Circuit-100°F-Flange/dp/B0026RYU4W

 

[Ackcruisers]

Thanks. Found some others overseas that I will test with variable temp for the exact OEM specs for temp On/off with either a normally open state or closed. I’ll post once tested to confirm application.

 

[Ackcruisers]

@Engineer8000 when you looked at the fan relay controller, do you know what voltage it needs to see when ignition is off to open the circuit for the cooling fan to shut it off? In my testing environment, with key ON the ignition black wire has 12.6 volts. Does it need to be over 12.6v when running (charging) to open the cooling fan circuit?

When I test the controller hooked up to my CA spec harness, the cooling fan will run even when ignition is ON. It should not run when ignition is ON. It does shut off on its own in approx 18 min when IGN is OFF. So, timer function works.

I have the thermo switch hooked up to a simple On/Off toggle switch.

 

[Engineer8000]

I would have to test an early controller like yours to be sure but I can say on the later boxes, the ignition voltage has to dip below about 1.1 volts to reset the timer. I will check it out.

 

[iptman]

I seem to remember mine not requiring the ignition to be off for the fan to kick on. I'll see if I can verify that today.

 

[Engineer8000]

Just checked the schematic and bench tested to confirm (85927-60010). The fan will cycle with the thermo disc switch any time the ignition is on, and for about 18 minutes after the ignition is turned off. The only function the IGN input has is to charge up the capacitor for the timer circuit that begins to count down after the IGN is turned off. As long as the IGN is hot, the timer cap stays charged and the fan runs with the temp sw. The internal relay drops out when the voltage on the GR wire falls below about 4.5 V and picks back up at about 7.5 V.

 

[Ackcruisers]

This is awesome information and very much appreciated. Thanks for taking the time to connect it up to get the information…Given that the cooling fan will stay on as long as the snap switch closes the circuit at temp, it’s important the switch has the right temp rating. I purchased a 170, 180 and 185 degree ON snap switch and will test all and report back for which one works best.

If anyone has a 1976 CA Spec Emissions Manual and can look-up the switch specs, we will close the chapter on this version (85927-60010) of the carb cooling fan.

 

[Engineer8000]

I have that manual but don't think there is anything in there about the carb fan. I will run out and check.

 

[Engineer8000]

Nothing in the 76 or 77 emissions manuals about the carb fan. The only place I have seen info on these is in the Toyota "new systems" books.

 

[Ackcruisers]

@Brian/99uzj100 I know you have a 1976 CA Spec FJ40, do you have any service manual documentation on the carb cooling fan switch wiring specs? I saw you had the thermo snap switch in this post.

California Spec Emissions sub-harness help

I am refurbishing a 1976 FJ40 California spec main cowl harness. It has a 6 pin emissions connector on the main harness that this sub-harness plugs into. There are two sub-sub-harnesses that plug into this sub-harness. I do not have these two sub-harnesses so have no idea how long they are...

forum.ih8mud.com

 

[Brian/99uzj100]

@Brian/99uzj100 I know you have a 1976 CA Spec FJ40, do you have any service manual documentation on the carb cooling fan switch wiring specs? I saw you had the thermo snap switch in this post.

California Spec Emissions sub-harness help

I am refurbishing a 1976 FJ40 California spec main cowl harness. It has a 6 pin emissions connector on the main harness that this sub-harness plugs into. There are two sub-sub-harnesses that plug into this sub-harness. I do not have these two sub-harnesses so have no idea how long they are...

forum.ih8mud.com

There's not much, but here's what I could find in the owners manual and the Emission Control CA Supplement.
I looked in the Chassis and Body FSM under body-electrical, but didn't find anything.
Hope this helps.