1981 FJ60 - heater fan circuit help needed (2 Viewers)

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I need some schooling on the wiring circuit on my 60. It's an 1981 glasses-fused truck, but looking at the POS Haynes book I have the wiring diagram seem to match a 1982.

The heater fan stopped working and while tracking down the issue I discovered that behind the fuse block, the 10a fuse for the AC has a bumper line drawing power from the 10a turn signal fuse post. This bandaid fix is where my short was and the heater fan is running again, but at best this was a PO half ass fix.

If I'm reading the Haynes wiring schematic correctly, the fan's power comes from the alternator to a circuit breaker to a relay then on to the fan. The negative side of the fan travels to the dash switch and/or a resistor for speed control. The control side of the relay is triggered by a second line from the switch.

For what I can tell, the AC fuse that I had to jump, is in line AFTER the relay and heads off to the AC switch. Seem to suggest that if the fan switch isn't on then the AC fuse wont get power to the AC switch.

FINE!

But that doesn't seem to be what's happening. Jumping power to the dead side of the AC fuse actives the circuit and the fan runs.

Questions,
1) where should the pre-fused side of the AC fuse get power from?
2) How should the fan circuit work?

Any light would be appreciated.

Thanks,
Carl
 

OSS

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Check out the back of the Body FSM. It has all the wiring schematics.

image.jpeg
 

g-man

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Power to your 10amp a/c fuse is coming from the 30amp heater breaker. If this goes no a/c and no blower. You can pull the breaker and using a small pin or finishing nail re-set it. If your system was overloaded or someone crossed hot wires up trying to mess with the fuses they could have burned up the ground wires. They are white with a black stripe and all come together in the harness that comes in from the firewall below the dash and feeds the relays. The grounds all are crimped together and go to a larger single wire that bolts under the dash near the fuse box. For me I ended up running a hot wire with a 30a inline fuse through the pass side firewall and to the dash. I used one of the blank switch locations on the dash and put a toggle switch. Then ran the wire to the hot side of the fan and used a single male blade to go into the plug. I made a short jumper to go to the other side of the plug. This feeds back to the fan selector speed and a/c switch.
 
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g-man

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I just have to remember to turn the switch off because it is not run through the acc on the ignition so its hot if I leave it on.
 
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This is exactly what I suspected.

If I’m understanding this wiring diagram correctly, and based on your post(s) it would seem that I have two shorts. The first on the relay/circuit breaker feed, and the second on the AC fuse feed.

And it would seem the current jerry-rigged system bypasses the relay all together.

This is all based on the diagram posted about - it’ll have to wait until the weekend before I can feild test it.

Do you guys agree with my thoughts?


You are backfeeding power to the fan by energizing the a/c fuse from the turn signal fuse.
 

OSS

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I just have to remember to turn the switch off because it is not run through the acc on the ignition so its hot if I leave it on.

I have my fan wired the same way - BUT I wired a relay from the ACC switch circuit (don't remember which fuse it was). This way, when the key is OFF, the relay will de-energize and the fan won't have power, but if the key is on ACC or ON, the fan will work.

Wiring the fan power via relay to be controlled by ACC switch (and not just ignition as it originally set up) lets you run the fan on low while the engine is off if sleeping in the car when it's raining. Of course you can't run it like that for too long (it draws 3.3A on low) but it can give you some ventilation for a couple hours when the engine is off (key on ACC).
 

g-man

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I have my fan wired the same way - BUT I wired a relay from the ACC switch circuit (don't remember which fuse it was). This way, when the key is OFF, the relay will de-energize and the fan won't have power, but if the key is on ACC or ON, the fan will work.
 

g-man

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I was thinking of doing the same thing today. Running a wire from the ignition to a relay to control the fan power.

Also should be noted the wire I used to run from battery to the toggle switch and to the fan was 12 to 14 gauge. I tested my fan at 15 to 18amps draw at wide open.
 

g-man

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cederholm...start off by making sure your 30amp heater breaker is reset. this is in the upper right hand side of the fuse box ..large metal piece. Stick a finishing nail in the hole until it clicks and it should reset. The problem may be that as soon as you turn on your fan or a/c on high...it trips again. If so, then you have a short, bad ground, burned up wires or whatever. You may get lucky and find it fixes your problems.
 
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g-man, the relay is hanging below the dash - not sure where it's suppose to attach. The top of it is missing and the element inside is exposed. When tested, current is present at the element inside and I believe current is passing through, but I will test it further.


cederholm...start off by making sure your 30amp heater breaker is reset. this is in the upper right hand side of the fuse box ..large metal piece. Stick a finishing nail in the hole until it clicks and it should reset. The problem may be that as soon as you turn on your fan or a/c on high...it trips again. If so, then you have a short, bad ground, burned up wires or whatever. You may get lucky and find it fixes your problems.
 
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The relays are upside down and close the firewall. Can anyone tell me which relay is which? Please remember this is an early 60 with glass fuses.
 
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Been staring at the diagram above and I'm confused about the path of the current and the comments below.

Current comes from the battery through B to the 30amp breaker then to the the relay. when it exits the relay it travels to the fan motor, but it also connects to the 10amp fuse AND line D. Does D draw currents from the ACC post or does it power the ACC circuit? The later would make sense with the second quote.

And in my case it would mean that ALL my ACC connections are being powered buy a jumper wire? Eeek!

Thoughts? Thanks!

B is coming from battery through a fusible link, D is coming off your ACC post on the back of your ignition switch.

Power to your 10amp a/c fuse is coming from the 30amp heater breaker.
 

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