[AT] tractor electrical question

[John Hall]

Ken, you summed this situation up perfectly, right down to the pink 
resistor wire. Everything I researched in 2 days you put into 2 
paragraphs, right down to what the wire is made of!

John Hall


On 8/27/2021 9:21 PM, Ken Knierim wrote:
> On the 1960's Ford vehicles (and others, I'm sure) they had a wire in 
> the harness that was specifically resistive which seems to match some 
> of the descriptions given. If wire has 12V on one end and 6V on the 
> other end going into the coil, it's like having the resistor inline. 
> The vehicles had a wire from the solenoid to the coil that would 
> bypass the resistive element in the harness by going straight to the 
> battery for starting purposes, giving full battery voltage (albeit 
> drawn down by the starter) to make the spark hotter (since the battery 
> voltage would drop severely during cranking it made starting hard). 
> The coils were set up to run on 6-8 volts to make this work. If this 
> is the same in your tractor application it could be part of what 
> you're seeing. These wires are generally nichrome wire and have a few 
> ohms to them (should be enough to measure on a DVM if disconnected 
> from the rest of the circuit; it should be similar to a resistor 
> inline as it does the same function). Nichrome wire is pretty 
> resilient to aging but connecting to it (with perhaps a crimp 
> connector or something like that) could be a problem over time.
>    Since you're able to get the thing to work correctly with a jumper 
> from the battery it seems there is resistance somewhere. I think you 
> mentioned having 12V at the switch but 6V at the coil when sitting 
> still and the points closed. That sounds like a resistive wire in the 
> harness. My thinking would be to run a new wire from the switch, 
> through a regular ballast resistor and to the coil to bypass the 
> potentially bad resistive wire in the harness (it may be heating up 
> and the connections giving you fits).
>
> Just my $0.02 but those pink Ford wires hosed a lot of folks over the 
> years.... :)
>
> Ken in AZ
>