Instrument panel swap

[dmichel123]

My father and I have installed an instrument panel with gauges instead of idiot lights. We never got the ammeter working and I've found out reading around on here that the wiring for the two is different. This post http://www.fordification.com/forum/view ... &sk=t&sd=a says to connect a purple(exciter) wire to the green/red wire. I've got the green/red wire, but didn't locate the purple when I looked for it. My dad thinks he has a bad battery, I think the alternator isn't charging because the green/red wire isn't connected to anything anymore. What should this wire be connected to? 12V? or?

[Dragon]

http://www.fordification.com/wiring.htm

Try this there are both light and gauge wiring diagrams. Wire diagrams wiring_69gauges.jpg and wiring-diagram-72_quick.jpg show the two different wire systems. Ignore the F350 only stuff it has no effect on your problem.

http://www.fordification.com/images/sch ... _quick.jpg 1972 F-series quick-reference diagram

http://www.fordification.com/images/sch ... gauges.jpg 1969 F-100 thru F-350 gauges

The ammeter is supposed to have a fuse or fusible link in both legs of the gauge.

[Thunderfoot]

The wiring is routed a bit different over the years and some other options on the truck will effect how there were routed... (not sure what year your truck is) but there should be a wire from the ignition switch that should be exciting the alternator still... Be sure this Green/Red wire is not grounding out on anything, and then using a "Test Light" or "Volt meter"(with the key on and the motor off) check the "Green/Red" wire at the "voltage regulator" for power, if it has power then it should be ok (working) if it doesn't then try hooking that Green/Red wire, that you have at the instrument cluster, to a 12 switched source.

Let me know what you find out and will help more from there.

[dmichel123]

Sorry for not being specific. The truck is a '68 and I don't want to hook up the ammeter. I just want to be sure the battery is charging. I just got a new battery from autozone, and i'll find out if it's draining with the ignition off or simply not charging when it's on.

[Thunderfoot]

68 should be ok from what I'm seeing in the wire diagrams, it should still be getting power from the ignition switch via a black wire that joins with the Green / Red wire...
Let us know what you find out with the new battery and if you still need more help.

[SteveC]

makes sense with the test light i forgot about that
Another thing ive seen done is a buzzer or some kind of similar thing that makes sound and has bigger wires than the test light works as well.

[Dragon]

A wiggy does that. A Cheap digital meter with one needle probe and one clamp probe that is kept out of the tool box will last a long time and solve many problems.

My Fluke 87V can do anything the old Rotunda (Ford test equipment meter) could do and more but they are very expensive. I still pick up my test probe on cars where it is hard to find a connection point.

[SteveC]

true i dont know why i didn't think about a digital volt/ohm meter. they can make life much easier

[Dragon]

And most people can not read a d' Arsoval meter (needle) any more. They are as hard to read as the true name is to spell.

[fordman]

d ardvark? is like peppy le pew?

[SteveC]

they are hard to read im not sure i can fully understand how to read one

[fmartin_gila1]

That's why the meter face has the mirror behind the needle, so you can ensure you are looking at it square on. The buzzer is something I have used for years to chase down shorts and such, especially good when you can't keep an eye on the light, you can always hear the buzzer till you have eliminated the short or draw. I use a buzzer that once signalled that you had left the key in, loud enough to hear from anywhere you may be hunting the short/draw.

Fred

[Hawkrod]

68 should be ok from what I'm seeing in the wire diagrams, it should still be getting power from the ignition switch via a black wire that joins with the Green / Red wire...
Let us know what you find out with the new battery and if you still need more help.

I could be wrong but I actually do not think that is correct. The alternator gets excited through the bulb in the dash and if the green red wire is not hooked up then the alternator will not charge. The other wire hooked to the green red wire should be the wire to provide power while cranking to test the light bulb. I do not have a 68 diagram to check this on but the other diagrams I have show it that way. Hawkrod

[Dragon]

That's why the meter face has the mirror behind the needle, so you can ensure you are looking at it square on.
Fred

Cheap meters don't usually have the mirror.

[Thunderfoot]

68 should be ok from what I'm seeing in the wire diagrams, it should still be getting power from the ignition switch via a black wire that joins with the Green / Red wire...
Let us know what you find out with the new battery and if you still need more help.

I could be wrong but I actually do not think that is correct. The alternator gets excited through the bulb in the dash and if the green red wire is not hooked up then the alternator will not charge. The other wire hooked to the green red wire should be the wire to provide power while cranking to test the light bulb. I do not have a 68 diagram to check this on but the other diagrams I have show it that way. Hawkrod

Hawk,

Here is the diagram from the 69 that I cleaned up to make it easier to see. (the 67 and 70 are the same and 68 should be as well)

If you look at all the lines I have colored “RED” #297, #98, and #30 these are all “Power = 12V” when the key is turned ON, #297 is the power wire to the fuse box and also power to the instrument panel via #30... #98 is the excite wire to the Voltage Regulator, and even though it doesn’t show it I believe this is a resistive wire as shown in the 71-72 wire diagrams (as a purple wire in those years)… The Lines I have colored GREEN are the wire #904 from the “ALT light”

EDIT: On the 70 diagram is shows #98 as a resistive wire...

The charge light comes on (and is checked) from the voltage regulator grounding internally until the alternator starts charging. So with the key on the light gets power from the #30 wire and is grounded through the Voltage Regulator via #904 wire, even though #98 is also hooked up in this line they are both being grounded from the regulator so the light comes ON. Once the alternator starts charging it stops grounding this circuit and the light goes out.

Let me know if you have some different diagrams from what Keith has here on the main site that I can look at…