1975 FJ40 Instrument Panel Not Working

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At the WL wire at the fuse panel, it's got 11.98 volts...ignition switch on (engine not running). So, that would mean it has a fusible link, correct?

The BY fuse into the panel is good and displays 0.0 OHMs when I pull it out and test it (they are new fuses). In my fuse panel above picture, I tested the fuse second from the bottom because I feel like that is the correct fuse location based on the wire location, correct? (I also tested all fuses and all are good). Quick question...when I tried to put the voltmeter on the fuse with the ignition switch on (engine not running), there was a drop in the electric fuel pump noise like a load had been added to the system. There was a slight snap at the fuse location. That did not seem right?

I'll shrink tube the WL and BY wires.

I don't have the fuse panel cover, but have been using the one below as a model because it looks identical to mine.

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The voltage at the WL wire confirms you have continuity, not that there is a fusible link present. My guess, and it is just a guess, is that the small red wire is not a fusible link. They generally are marked "Fusible Link."
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"Quick question...when I tried to put the voltmeter on the fuse with the ignition switch on (engine not running), there was a drop in the electric fuel pump noise like a load had been added to the system. There was a slight snap at the fuse location. That did not seem right? "

Did the fuel pump stop or just change sound? If it stopped check the fuse again as you may have shorted the test lead to something and popped the fuse. If the fuse is good the snap may have been the fuse seating into the contacts from the pressure of the probes pushing on it. As the fuel system pressurizes you may hear the pump sound change. It also maybe unrelated to what you are testing and another issue that needs to be addressed down the road.
 
It just changed sound and did not stop. The fuse was good after that event. It may have been unrelated, but coincidentally timed.

I think that wire going to the POS Battery terminal is just a wire the PO added...I'm going to add a fusible link there...

Btw...thank you for helping and spending time trying to figure this out.

I have to be missing something...I took the Voltage Reg out and looked at it and it's good. see picture. The Alternator now with engine running is around 11.8 volts.
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You are welcome...that's the only reason for being here!
You are measuring battery voltage, time to put a charger on.
I don't know why I didn't think of this before now but you can take the alternator into a local parts store and have them test it too.
 
That's a plus!! Do you have another voltage regulator? The only thing in the charging circuit is the voltage regulator, the alternator and the battery. Just need to make sure the connections are correct, clean and tight. Also make sure there is a good, clean ground between all three components. This is where the patience and perseverance comes in.:)
 
You are not kidding about patience. I don't have another Voltage Regulator...the one on the truck before I got it was fried. I supposed I can order another one and return it if doesn't change anything.

Grounds, the battery and alternator both had the grounds going to a bolt on the frame (it was a bold that holds the radiator stabilization arm). I took both wires from the alternator and battery off, cleaned the connections and the frame (with wire brush) and reinstalled. Got a little change in volts...went from 11.84ish to about 12.4ish. Cleaned the connections going to the voltage regulator. Same result.

I did add a fusible link to the POS wire (see picture).

I guess the next step is to get another voltage regulator? Can there be something at the fuse box preventing a proper ground?

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A ground at the fuse box shouldn't affect the system since you have cleaned the grounds at the alternator and battery ground point and seen a positive change, . The only thing left is the voltage regulator. Sorry it took so long to answer, had to fry some cannoli shells for dessert.
 
Ok...will order a VR and see what happens...I'll let you know when it comes in.
Maybe you should come to our house to cook cannoli shells! Sounds awesome!
Thank you again for everything.
 
Groucho263 said:
The R wire into the ground would be a good reason the voltage regulator was fried when I got this thing.

I think I have it wired correctly now...(see picture). Alternator volts are roughly 12 (slightly over at maybe 12.21 on average). I think that alternator is bad. Ammeter still shows discharge and lights now don't work.
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Is this the F terminal?
 
That's a good question...I could have that wrong, but tried to figure it out based on a few other schematics. I haven't seen a good picture with labels, etc. That is the green connector that is attached to the alternator. The wires don't have a connector (I think I have to get one eventually from @Coolerman). So, the wires are going directly into the alternator, not a connector. I'll try to put the WB wire into that connection and see what happens?
 
Here are some answers for your wiring.

Look at post #6 HERE.

Look at post #9 HERE.

Hope this helps. :edit: It looks like you are wired correctly at the alternator based on the two threads I found.
 
Yeah...I think it was wired correctly. I had been through those posts too and concluded the same. I tried to put the WB wire in the top terminal and still the same from the alternator...just under 12 volts. I ordered the VR last night from SOR (can you believe they were the cheapest...)
 
" I ordered the VR last night from SOR (can you believe they were the cheapest...) " Yeah right...at least you still have a sense of humor after all of this.:rofl: Keep us in the loop and I really hope that fixes this portion. Then the real fun begins.
 
Another quick question...doing some reading from @Coolerman and he says the following about grounds. Post #7: FJ40 Turn Signal Trouble shooting
A. The main ground for the system is of course the battery negative cable to chassis. There should be TWO grounds: One from the battery to the frame rail, then from that point a short jumper cable to the starter mounting bolt on the engine block. This provides the frame and engine block with good solid grounds. Note that the engine is mounted to the frame with rubber isolators so the engine may not be grounded well through its mounting bolts, IE the reason for the jumper. Engine ground is really important for the starter AND the alternator to function properly. Also idle solenoid, temp sensor, and the oil sensor.

My alternator has a ground wire similar to the battery ground that connects to the frame (see picture). I don't have a ground wire from the battery ground point to the starter mounting bolt o the engine block? Do I need to fix this?

I also don't have this I don't think:
B. Next are the wiring harness grounds. The primary harness ground on older trucks is located at the external regulator. There is a WB wire that comes from the harness and attaches to the regulator E terminal. The E terminal is directly connected to the regulator case therefore the regulator case MUST be well grounded to the body! This ground is critical! It is the ground wire for the alternator, headlights, VSV, heater blower and wiper motor!

The WB wire from the Voltage regulator goes in the main wire bundle and is attached to another WB wire (I haven't followed it to see where it goes). I don't think this WB wire is grounded to the body. I think I need to fix that too?


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Coolerman is the electron guru of Mud. His writings should be treated as gospel due to his knowledge and experience. Grounds are the foundation for all things with little electrons flowing through them, without good ones the electrons flow to places they don't belong and cause weird things to occur. If there are missing grounds please correct that. Also as you found out with the alternator grounds clean connectors are rewarded with better performance. This is a great catch. Also if there is a sudden change in performance in something electrical ie. parking light starts to blink when the flashers are on, clean the connections and insure the grounds are good.
 
I'm going to have to figure out how to run a ground wire from the battery ground to the starter mounting bolt.

Going thru the wires 1 at a time and noticed the IG Coil fuse (second from the bottom 15A) is blown again. (The BY wire from the voltage regulator (it Y's and 1 line goes to the fuse panel and the other line goes into the main wire bundle...I am still tracing that one). This is a bad sign. I think the VR is supposed to get here tomorrow and hopefully that fixes something. If the IG Coil/Engine fuse is blowing, there is a short someplace? Or is the Voltage Regulator not working correctly? The only BY wire on the passenger side of the vehicle coming out of the wire bundle goes to the Ignition Coil.

Here is another question...I don't think I have an Ignitor unless my Ignition Coil has it internally?
 
Which wiring diagram are you using?

According to the wiring diagram I have for the 1975 FJ40 it shows a single BY wire from the fuse panel to the IG terminal of the voltage regulator. This should have voltage when the ignition switch is in the on position.

There is another circuit that uses a BY wire going from the ignition switch to the electronic ign and coil and to the hot side of the fuse panel powering the fuses with BY, GR and LR wires on the output. I believe this is the power for the switched circuits on the fuse panel. Since you don't have an ignitor (electronic ign) then that BY wire should be missing or insulated (hopefully.)
 
If a fuse blows it is from one of three reasons:
1) it is a defective fuse
2) there is more load or starting inrush current on the circuit than the fuse is designed to handle
3) there is a short
 
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