Another F600 wiring question

[theogre5150]

Ok. I am replacing my cluster with one from an F600. I have searched through the forum but I could not find the same issue that I am having. I have matched up all of the wires from my wiring in the truck to the harness from the F600. I am now down to two wires on each end. I can identify the wires from the harness (yellow and red - ammeter). The remaining wires coming from the truck are purple and green/red stripe. The purple wire is a thin single wire unlike any of the other ones that I stripped.

My original gauge in my 71 had idiot lights and this one from the F600 has all gauges. I have read through the forums and found a post that said if you originally have idiot lights, the ammeter hookup will not be there. Please help

[Thunderfoot]

The Amp meter wiring will not be there for that… You can find some info on the "Shunt" wiring needed for it in this thread. http://www.fordification.com/forum/view ... f=8&t=2094 but it will probably be easier to hook up an external Volt Meter Gauge.

The Purple wire is the exciter wire for the alternator from the ignition switch (it is a resistive wire) and the Green-red wire is where it continues to the voltage regulator for the exciter circuit. These 2 wires should have gone to the Alt light connection on your old instrument panel, your alternator will not charge without them hooked up… You should be able to just hook those 2 wires together so that your alternator will work right…

You will also need to change out the sending units on the engine for the Temp and Oil pressure as they are not the correct ones for gauges.

[theogre5150]

Do I need to get aftermarket gauges for this? What is the easiest and most cost effective solution?

[theogre5150]

Good idea on the light for the alternator. This way I can keep all of my gauges and not have to add any. I have three open holes on the panel so that would work just fine. Is there a particular side of that switch that I need to wire the purple and green/red wire to? Thanks for the info.

[Thunderfoot]

Is there a particular side of that switch that I need to wire the purple and green/red wire to?

You mean the "light" not "switch", right?
On the light, no it really makes no difference... Just be sure that the light you get is not grounded through the base and uses 2 wires/connections (ground and power) I would probably hook the Purple and Green/red to the ground connection and the power to the Black/green power wire to the instrument panel.

You'll have to post some pics when you get it all done.

[theogre5150]

I meant light, not switch. Do I need to splice into the Black/Green wire for this? I have already matched it up to the harness.

[Thunderfoot]

Do I need to splice into the Black/Green wire for this? I have already matched it up to the harness.

Nope, just any power wire that comes on with the key should work (just not the ignition wire) .

[seattle67]

Hey Eric, TF's idea is excellent and probably the way I would go if I was in your shoes. I just wanted to make sure you understood that with this configuration you will only have an alternator light, the ammeter will not function. Not really a big deal as the Ford ammeters never worked all that well to begin with

[theogre5150]

Shoot, even if the ammeter was working I would not know what it was telling me. Plus, I would notice a bright red light before I ever paid attention to that gauge. The only gauges I watch are temp, speed, and most importantly........fuel!

[theogre5150]

Hey Thunderfoot, I did what you said and bought one of those lights. I wired the purple and green/red stripe wire together and hooked up to the black/green stripe wire for power. The light comes on but does not go off. We did some tests and did not see a charge coming from the alternator so I replace it. The light still comes on. I went ahead and replaced the voltage regulator and the light still comes on.

Is there anything else I can check or need to do?

Thanks

[Thunderfoot]

Hummm… kind of sounds like maybe there is a short somewhere. I have attached a simplified diagram of the excite wire with the idiot light, wire #98 is shown as Black in this diagram but for your truck (71-72) it is the Purple wire… This is the actual excite wire for the alternator and it should work with just it hooked up, the Green/Red (904) wire from connector © to the instrument panel is just for the light.

Anyway, take a test light and check the Green/Red wire #904 at the Voltage Regulator with the key on but the motor off, you should have power there, If you don’t then check just the Purple wire for voltage with the key on. If is doesn’t, try hooking the ground lead of the tester to this purple wire and probe to 12V power and see if the test light lights up. If it does then there is a short in the purple wire to the ignition switch. If it (purple wire) has voltage then check the Green/Red wire from the Voltage Regulator all the way back to the cab for shorts to ground.
If you did have power on the Green/Red wire at the Voltage Regulator then there is an issue with the wiring to the alternator or problem with the Voltage Reg or Alt. I know you said you replaced them but it wouldn't be the first time I've gotten bad new parts.

Let us know what you get from these checks and we’ll go from there.

[theogre5150]

I'll let you know as soon as I get a chance. Thanks for getting back with me. Also, do you think it may be the fuseable link? I looked at it and it looked like the wire did the twist.

[Thunderfoot]

I'll let you know as soon as I get a chance. Thanks for getting back with me. Also, do you think it may be the fuseable link? I looked at it and it looked like the wire did the twist.

If you measure 12V at the alternator on the (+) cable with the motor off then the fuseable link good, but if you don't have any voltage there then yes this would be a problem. You can test this with a test light as well just check the (+) cable connection on the alternator and it should have voltage from the battery with the engine off.

[theogre5150]

I noticed that there is a black wire with a red stripe coming from the alternator harness going to a bolt for the voltage regulator. This wire is fried. It melted the tape from one end to the other and even split the tape open in one spot. Could this wire be the culprit?

[Thunderfoot]

I noticed that there is a black wire with a red stripe coming from the alternator harness going to a bolt for the voltage regulator. This wire is fried. It melted the tape from one end to the other and even split the tape open in one spot. Could this wire be the culprit?

that is not something good that's for sure... That should be the Ground wire for the Voltage Regulator It is wire #26 in that diagram I posted above. You will want to take and un-rap the wire harness and follow that wire to see for sure where it goes(I'm not 100% sure it goes to the Alternator) and see if it has melted into (shorted with) some of the other wires for the Alternator. This could lead you to the problem.
Let us know what you find and take some pictures if you can.

Also, do double check your ground connections from the engine to the battery and from the engine to the cab and make sure they are good, I have seen when these get bad that it (current) tries to use that small wire to the Voltage regulator as ground and it is not big enough to handle it...