74 FJ40 wiring question (1 Viewer)

[musthave]

Trying to finish my sons FJ40. Much closer.

Harness is in, many things are connected.

On the PS I have 3 wires, black/yellow, black/white and black.

Black/yellow I have going to the ignition coil.

Black white I only have going to starter, does it go to ignition coil as well? Where?

Black is sitting there, what does it go to? I'd assume ground but I'm probably wrong. My diagram doesn't show it

 

[Living in the Past]

What market is the 40 from? What diagram are you using? I do not see any type of ignitor or emissions. Black is generally not a ground on FJ40 wiring.

 

[musthave]

The three wires come out of the harness together right near the ignition coil.

1974 FJ40, US spec

Using a diagram from classic cars.

These are the three wires. Black/yellow. Black/white. And black.

 

[musthave]

Same as this diagram. in regards to the black/white wire, I don't know what it attaches to on the ignition coil. From the harness, close to the ignition coil, I have three wires. One of them is black/white that I would assume goes to the ignition coil or the starter. Or both.

I have no idea what the black wire connects to.

 

[Malleus]

Well, you need (2) power conductors for the starter; one for the solenoid and one for the starter motor. If your starter is wired as per the EWDs above, and the starter only have one hot lead, the lone black wire you have should go to the motor.

 

[musthave]

Well, you need (2) power conductors for the starter; one for the solenoid and one for the starter motor. If your starter is wired as per the EWDs above, and the starter only have one hot lead, the lone black wire you have should go to the motor.

I have one positive thick cable going to the starter.

The 2nd smaller connector has a contact with a length of wire that I ran. Previously if tapped to positive it cranked. In the diagram it shows a black/white wire to starter which is what I have currently. Should it be to the lone black wire?

 

[Malleus]

No, the power conductor to the starter motor has to be quite large; it carries a lot of current. It should be red as well (mine is).

The solenoid conductor is (from memory) 16/18 ga. That should be the B/W wire in your EWD above.

Where did the harness come from?

 

[musthave]

No, the power conductor to the starter motor has to be quite large; it carries a lot of current. It should be red as well (mine is).

The solenoid conductor is (from memory) 16/18 ga. That should be the B/W wire in your EWD above.

Where did the harness come from?

The main power positive to the starter is probably eight gauge.

So, it sounds like the solenoid conductor should be the black/white wire. Which makes sense on the diagram above. So the black white wire from the harness then goes to what? The starter or the ignition coil?

It is the original harness. In excellent condition.

 

[h82crash]

The main power positive to the starter is probably eight gauge.

So, it sounds like the solenoid conductor should be the black/white wire. Which makes sense on the diagram above. So the black white wire from the harness then goes to what? The starter or the ignition coil?

It is the original harness. In excellent condition.

According to the diagram, if you already have the start wire to the solenoid, then the other B/W goes to the coil side of the resistor, which should be mounted right next to the coil. If my memory serves right, it provides a boost to the coil during start up as it bypasses the resistor.

 

[musthave]

I have a single bw wire to the starter, but it doesn't get 12v to it when turning key to start. I don't have a 2nd bw wire that appears to go from solenoid to igniter. My 2F is from a 60 with a new oem starter. Only 2 plugs, one for bw from harness, one for 12v + to battery. Not sure where a 2nd bw would connect to on solenoid or igniter.


Should the starter solenoid get 12 V from the BW wire when key is in the start position?

Or, does the 12 V come from the BY wire that has 12 V as long as the key is in on or start position?

I'm not making sense of things.

 

[45Dougal]

I have a single bw wire to the starter, but it doesn't get 12v to it when turning key to start. I don't have a 2nd bw wire that appears to go from solenoid to igniter. My 2F is from a 60 with a new oem starter. Only 2 plugs, one for bw from harness, one for 12v + to battery. Not sure where a 2nd bw would connect to on solenoid or igniter.


Should the starter solenoid get 12 V from the BW wire when key is in the start position?

Or, does the 12 V come from the BY wire that has 12 V as long as the key is in on or start position?

I'm not making sense of things.

Well first of all, yes, when you turn the key to "start" it should connect the 12v feed from the battery through to the starter solenoid. Check voltages at the switch connector.

The BY provides 12v to the coil for normal running via an internal resistor (check the fuse voltage).

When you turn the key to start, the battery voltage is lower because of the starting load, so there's an extra BW wire to provide 12v directly to the coil (without the resistor) to boost the spark a bit.

I would focus on getting the motor to spin, and make sure you have 12v at the BY to the coil. Worry about the boost wire another day.

 

[musthave]

Well first of all, yes, when you turn the key to "start" it should connect the 12v feed from the battery through to the starter solenoid. Check voltages at the switch connector.

The BY provides 12v to the coil for normal running via an internal resistor (check the fuse voltage).

When you turn the key to start, the battery voltage is lower because of the starting load, so there's an extra BW wire to provide 12v directly to the coil (without the resistor) to boost the spark a bit.

I would focus on getting the motor to spin, and make sure you have 12v at the BY to the coil. Worry about the boost wire another day.

I've got 12v on the BY. Not on BW. More tomorrow.

 

[45Dougal]

BW should be hot when you turn the key to start.

If it isn't, then check BW at the ignition switch connector - you probably have a dirty switch contact or connector corrosion (the feed to the switch is known to be good since you have 12v at BY).

The only Black cable I see on my diagram is for the glow plug controller on my diesel engine - maybe you don't need it.

 

[ToyotaMatt]

Does this clear things up @musthave ?

 

[musthave]

BW should be hot when you turn the key to start.

If it isn't, then check BW at the ignition switch connector - you probably have a dirty switch contact or connector corrosion (the feed to the switch is known to be good since you have 12v at BY).

The only Black cable I see on my diagram is for the glow plug controller on my diesel engine - maybe you don't need it.

So, I tested for 12 V on the back of the ignition switch end at the first connector. When the key is in the start position, I get 12 V at both locations on the BW wire.

Tested for continuity between ignition switch and the BW wire on the passenger side fender, and get nothing. Seems a little odd.

Not sure what's best, perhaps run another wire from switch to fender? What gauge are they,14?

 

[pjohnson]

There's a fuse in that circuit. Check your fuseblock.

 

[musthave]

There's a fuse in that circuit. Check your fuseblock.

Between here and the PS fender? Hmmmm, I'll have to figure out where that is.

 

[45Dougal]

I don't see a fuse in the BW on the diagram.

There is a solder joint though buried in the harness somewhere - anyone remember where?

Otherwise unpick the tape and start searching. - it needs resoldering - grab some flux and a blow torch
A temporary bypass also works

 

[musthave]

Yes, if someone knows where that solder joint is that would be great. Otherwise I suspect that I will run a bypass but it would likely be permanent. I would prefer to avoid that.

 

[hobbes]

Here’s a colorized diagram stolen from here.

Let me know if that doesn’t help you. I can take a photo of my wiring if need be. I‘ve got a Coolerman trailer harness and adapter to run a 1987 alternator and dizzy setup, so it won’t be exact.