Speedometer wiring 74 FJ40 (2 Viewers)

[musthave]

I have two wires that I believe connected to the back of the speedometer. One is solid white, one is white with a blue stripe. Trying to figure out which one is negative and positive. I believe the striped one is negative, but want to be sure.

Next of the three connectors to connect to the steering column, one has an extra bullet style connector. What does that go to? Green white stripe.

 

[45Dougal]

White is + according to my diagram, but if they're the wrong way around then your gauge will just be backwards.
Green White I'm guessing is the extra US connection to the indicators?
For the extra effort, it's worth properly insulating those screw terminals while you have it off. It's easy to short to ground when fiddling about

 

[B y r o n]

A wiring diagram is your friend.

 

[musthave]

A wiring diagram is your friend.

I bought the one from classic car wiring but it doesn't seem to match.

 

[B y r o n]

Maybe one of these will help.

 

[musthave]

Maybe one of these will help.

Thank you for that diagram, that will probably help with some other items. However, looking at the back of the speedometer it doesn't match to the wiring diagram in the link for a 74.

On the backside of the speedometer, there is the multi function piece, and in the same end of that harness there are two wires, a white one, and a white one with a blue stripe. I presume that they connect to the positive and negative on the backside of the speedometer. That I can tell, none of the diagrams show those two wires.

Keep in mind, I am certainly no expert at reading the diagram so, if I'm wrong, feel free to correct me.

 

[B y r o n]

Terminology is a tricky thing sometimes. What you are referring to as the "speedometer" is actually the instrument cluster. The two wires you reference go to the amp meter. The positive terminal is the one closest to the outside edge and the negative is closer to the middle. The white wire is positive and the white/blue wire is negative. You can see the information in this thread.

 

[AKPoser]

I have two wires that I believe connected to the back of the speedometer. One is solid white, one is white with a blue stripe. Trying to figure out which one is negative and positive. I believe the striped one is negative, but want to be sure.

View attachment 3288223




Next of the three connectors to connect to the steering column, one has an extra bullet style connector. What does that go to? Green white stripe.
View attachment 3288224

I have two wires that I believe connected to the back of the speedometer. One is solid white, one is white with a blue stripe. Trying to figure out which one is negative and positive. I believe the striped one is negative, but want to be sure.

View attachment 3288223




Next of the three connectors to connect to the steering column, one has an extra bullet style connector. What does that go to? Green white stripe.
View attachment 3288224

Hope this helps.

 

[musthave]

Terminology is a tricky thing sometimes. What you are referring to as the "speedometer" is actually the instrument cluster. The two wires you reference go to the amp meter. The positive terminal is the one closest to the outside edge and the negative is closer to the middle. The white wire is positive and the white/blue wire is negative. You can see the information in this thread.

Got it, thank you. The terminology is tricky. The link is perfect in explaining. I had no idea that it was for the amp meter. Thank you, I'm learning, and I appreciate it.

 

[4x4veteran]

Do you have a 12 volt test light or a muti meter? It is a simple prosses.

 

[45Dougal]

If it wasn't clear that those thick wires went to the +/- studs on the ammeter, then maybe its worth pointing out that the White wire is connected directly to the battery, and the White blue feeds almost everything on the truck, so both have the potential to cause big problems if they fall off or touch something else.
Also hope you have the right ammeter (they're not all the same and have a tendency to go pop).
The metal dash aperture is a great place to short them out if you don't disconnect the battery.

 

[musthave]

Terminology is a tricky thing sometimes. What you are referring to as the "speedometer" is actually the instrument cluster. The two wires you reference go to the amp meter. The positive terminal is the one closest to the outside edge and the negative is closer to the middle. The white wire is positive and the white/blue wire is negative. You can see the information in this thread.

Got it, thank you. The terminology is tricky. The link is perfect in explaining. I had no idea that it was for the amp meter. Thank you, I'm learning, anf I appreciate it.

Do you have a 12 volt test light or a muti meter? It is a simple prosses.

yes, but no battery installed yet. Trying to put things back together after body off. Thank you

 

[musthave]

If it wasn't clear that those thick wires went to the +/- studs on the ammeter, then maybe its worth pointing out that the White wire is connected directly to the battery, and the White blue feeds almost everything on the truck, so both have the potential to cause big problems if they fall off or touch something else.
Also hope you have the right ammeter (they're not all the same and have a tendency to go pop).
The metal dash aperture is a great place to short them out if you don't disconnect the battery.

View attachment 3288674

Thank you for sharing that. I didn't know thst about those wires. Learning. Thank you

 

[4x4veteran]

Got it, thank you. The terminology is tricky. The link is perfect in explaining. I had no idea that it was for the amp meter. Thank you, I'm learning, anf I appreciate it.

yes, but no battery installed yet. Trying to put things back together after body off. Thank you

If you have a multi meter then put the switch on continuity, put one meter lead on the neg bat cable and the other lead on the wires in question. The one that buzzes or shows continuity is the neg. To be sure switch the lead from neg to pos cable and the one that buzzes is pos.

 

[ukboneman]

Both sides of the ammeter are positive. Current from the alternator, via the blue and white wire, pass through the ammeter and goes to the battery via the white wire through the fusible link. The ammeter uses the electromagnetic field generated by the current to measure amperage. Sparks will fly if either is connected to negative. Both sides of the ammeter should measure positive with the engine running. If current generated by the alternator is greater than the amperage used by various devices including the engine, then it is positive. If the electrical drain on the system is greater than that being supplied by the alternator, then amperage is negative. the negative from the battery and the alternator goes through the frame.

 

[musthave]

Both sides of the ammeter are positive. Current from the alternator, via the blue and white wire, pass through the ammeter and goes to the battery via the white wire through the fusible link. The ammeter uses the electromagnetic field generated by the current to measure amperage. Sparks will fly if either is connected to negative. Both sides of the ammeter should measure positive with the engine running. If current generated by the alternator is greater than the amperage used by various devices including the engine, then it is positive. If the electrical drain on the system is greater than that being supplied by the alternator, then amperage is negative. the negative from the battery and the alternator goes through the frame.

Excellent explanation, thank you.

 

[hobbes]

Coolerman’s list of wiring diagrams by year.

Cruiser Wiring

Below is a colorized version of a 1974 wiring diagram. Be warned, these aren’t perfect.