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"S**T!" It's a Resistor Wire- Wiper Switch to Gauge Cluster?
#1
What is the purpose of the resistor wire (black/green) which runs between the wiper-washer switch (has 8 wires + the resistor wire) and the 12 pin dash cluster connector? ('73 Mach 1- Q- Code, has factory Tach but that's a separate question) It is a black single strand wire, which has green lettering on it "resistor wire do not cut or splice." I noticed the lettering AFTER I cut it to make a repair to it. (Insulation was deteriorated in one area.) I overlapped the wires in a butt connector and mechanically crimped them together. Is this okay?
   
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#2
Find out and let us know. I'm betting it will be fine.

Going fast is fun but life is short so slow down and enjoy the ride Big Grin Frank
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#3
EBSTANG;215028 Wrote:What is the purpose of the resistor wire (black/green) which runs between the wiper-washer switch (has 8 wires + the resistor wire) and the 12 pin dash cluster connector? ('73 Mach 1- Q- Code, has factory Tach but that's a separate question) It is a black single strand wire, which has green lettering on it "resistor wire do not cut or splice." I noticed the lettering AFTER I cut it to make a repair to it. (Insulation was deteriorated in one area.) I overlapped the wires in a butt connector and mechanically crimped them together. Is this okay?

What is the purpose of this resistor wire?...other that to provide resistance, of course. Why resistance is this situation...wiper switch to gauge cluster...
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#4
Midlife can better answer this question but this is my thoughts here. I believe that it is supplying power to the CVR for your gauges. From what I can tell is that the CVR requires 12v on its input and outputs between 0 to 6 volts to the gauges. Since the voltage is not always 12v in the system (when battery is charging it's about 13.7v) this resistance wire is used to try to keep it as near 12v as possible. I don't think that it will break anything by splicing but could possibly affect the accuracy of the gauges. A easy check would be to check the voltage at the CVR input while the motor is running. This CVR appears to be a thermal switch so higher or lower voltage will affect its switching frequency. Again this is my thoughts here so don't take it as gospel.

-john
(jbojo)
351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,
C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

Some Mod pictures can be seen at:

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#5
As long as it is good crimp connection it should not be a problem The splice should yield a really, really near zero ohms resistance. As far as gauge accuracy, they will be as inaccurate as they were beforeTongue. Chuck
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#6
The resistance wire is to reduce the voltage to the regulator to 7 or 8 volts, which reduces the load on the contacts, heating coil, and bi-metal strip in the instrument voltage regulator. A 1/4 inch overlap will likely increase the voltage to the IVR by 0.1 or 0.2 volts, and should not be a problem.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#7
Dammit guys, you beat me to it! Yes, that wire provides reduced ACC power to the CVR on the dash cluster. A good crimp connector will get you back in business, although it is a single strand of nichrome wire and that is very hard to crimp positively. It's best to crimp it with another multi-stranded wire on each end of the butt splice and keep the extra wire out of harm's way.

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http://midlifeharness.com

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#8
jbojo;215060 Wrote:Midlife can better answer this question but this is my thoughts here. I believe that it is supplying power to the CVR for your gauges. From what I can tell is that the CVR requires 12v on its input and outputs between 0 to 6 volts to the gauges. Since the voltage is not always 12v in the system (when battery is charging it's about 13.7v) this resistance wire is used to try to keep it as near 12v as possible. I don't think that it will break anything by splicing but could possibly affect the accuracy of the gauges. A easy check would be to check the voltage at the CVR input while the motor is running. This CVR appears to be a thermal switch so higher or lower voltage will affect its switching frequency. Again this is my thoughts here so don't take it as gospel.
Thanks jbojo...when you say it may "affect the accuracy of the gauges" do you mean the gas gauge, as it's the only gauge in this cluster. Tach, gas gauge, and Speedo are the only ones in this cluster. If that's what you mean I will closely observe at fill up time...

c9zx;215062 Wrote:As long as it is good crimp connection it should not be a problem The splice should yield a really, really near zero ohms resistance. As far as gauge accuracy, they will be as inaccurate as they were beforeTongue. Chuck

Thanks c9zx,...since the single strand wire was such a thin gauge, I stripped it back about an inch on each end and sent each wire all the way through the butt connector (red) so they would not only get crimped by the connector but would also get squeezed together. I then slid some shrink tubing over it and sealed it up. Hope it works!

Don C;215112 Wrote:The resistance wire is to reduce the voltage to the regulator to 7 or 8 volts, which reduces the load on the contacts, heating coil, and bi-metal strip in the instrument voltage regulator. A 1/4 inch overlap will likely increase the voltage to the IVR by 0.1 or 0.2 volts, and should not be a problem.

Thanks Don...usually with a butt connector I wouldn't have an overlap at all but since the single strand wire was such a thin gauge, I stripped it back about an inch on each end and sent each wire all the way through the butt connector (red) so they would not only get crimped by the connector but would also get squeezed together. I then slid some shrink tubing over it and sealed it up. How will that effect the voltage?...still okay?

midlife;215128 Wrote:Dammit guys, you beat me to it! Yes, that wire provides reduced ACC power to the CVR on the dash cluster. A good crimp connector will get you back in business, although it is a single strand of nichrome wire and that is very hard to crimp positively. It's best to crimp it with another multi-stranded wire on each end of the butt splice and keep the extra wire out of harm's way.

midlife, to you I must give the greatest thanks...for some reason I cannot stop looking at your response(s)... Wink
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#9
If you have a center console gage cluster it would affect them too. Oil and temp for sure, not sure about the ammeter though.

-john
(jbojo)
351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,
C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

Some Mod pictures can be seen at:

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#10
Even with the longer overlap you should still be OK. The IVR will probably wear out a little faster, so you might want to consider a solid state electronic regulator.

Midlife is correct, it's not easy to keep nichrome wire crimped. It's not easy to solder, either. Silver solder and a good liquid flux should work on the crimped connection, if it seems like you're not getting voltage to the IVR.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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