3400 Ignition switch wiring...

OldIron

Member
Hello,

My old Ford 3400 gasser had a screwdriver switch, and me being the genius, I decided to buy a proper keyed switch, too many kids in the neighborhood...

I put all of the wires in exactly the same 'position', but I suspect the new switch may be a bit different than the old one.
It doesn't start perfectly anymore, and seems that the ignition cuts out when cranking, and once released the ignition kicks. This means when it's cold out she can now be a bear to start.

I bought the Wesco switch (a 7 blade switch with 4 positions - Off, 1, 2 and then momentary start). With 5 connections, two set of blades are double connections.

The numbers are as follows:
Double blade 1 and 4
Single blade 2, 3 and 5

Anyone have any idea which wires go where?

(There is one oversized blade, and that's an obvious one on connection 1...)

Any help appreciated...
mvphoto13915.jpg
 
Shaun,

Thanks so much. Unfortunately, it appears my wires have been replaced at some time in the past, clearly not original colors...

Any chance of getting what each wire color is?

Thanks again and sorry to be a pest...

OldIron
 
According to the schematic in the I&T Manual, the original key switch for gasoline engine tractors only had 3 terminals, and this is how it was wired:

Terminal #1 - 2 brown wires, 1 to light switch and the other to "B" terminal on Voltage regulator. There should be another brown wire from the "B" terminal on the VR to the + side of the battery.

Terminal #2 - 2 brown wires with red stripes, 1 to coil and the other to the fuse at the instrument panel.

Terminal #3 - 1 white wire with yellow stripe to starter safety switch in transmission, which only allows the tractor to be started while in neutral (or Park if S-O-S transmission). Wire from other side of safety switch goes to starter relay/solenoid.

Since you have 5 terminals on the new switch, I would use an ohmmeter to determine which terminals have continuity to terminal #1 when the switch is in the various positions. You want whichever terminal that has continuity to terminal #1 when the key is in the "Run" position to be connected to the wires going to the coil and instrument panel fuse, and the terminal that only has continuity to #1 when the key is in the "Start" position to go to the safety switch.
 
(quoted from post at 16:03:04 12/16/14) Shaun,

Thanks so much. Unfortunately, it appears my wires have been replaced at some time in the past, clearly not original colors...

Any chance of getting what each wire color is?

Thanks again and sorry to be a pest...

OldIron
his passed through awhile ago, maybe it will be of benefit?
 
All I have is old service bulletin 8-80 with new switchs at that time and a shop manuel from 1966 for the wireing. Took? from Ford dealership worked at that sold. We took all shop manuels so could get new ones. that didn't have messed up and missing pages.
 
Sean, Shawn and JMOR,

I thank you all for your help and patience.

I've ohm'd the switch, and the #1 is most certainly the 'hot' terminal.

Unfortunately, I'm starting to suspect that all this time I've had a defective new switch, or possibly the wrong switch?

Here's the ohm'd Terminal numbers and relative switch positions, all to 1 HOT:
ACCESSORY - 2(ACCESSORY)HOT --- (HEAT(3)+CRANK(5)+ON(4) open)
ON - 2(ACCESSORY)+4(ON)HOT --- (HEAT(3)+CRANK(5) open)
HEAT - 3(HEAT)HOT --- (CRANK(5)+ON(4)+ACCESSORY(2) open)
CRANK 5(CRANK)+3(HEAT)HOT --- (ON(4)+ACCESSORY(2) open)

Problem: No terminals have continuity during both CRANK and ON, so ignition (if connected to 2 or 4) cuts out while cranking, clearly no good.

What am I missing? Where would IGNITION lead go to work properly??
Is a jumper necessary? Would a jumper even work?

Thanks for the help and any ideas??

OldIron
 
With all of your help and input, I decided to jumper the HEAT and ACCESSORY terminals and put the ignition on the ACCESSORY terminal.
All runs/starts as it should.
I also labeled every darn wire for the next time I have an issue...
Thanks to all.

OldIron
 
OldIron,
If you wanted to get fancy and you have a 6 volt coil on this tractor (one that requires an external resister), you could hook up 2 wires to the coil! One that goes from the on lug using the resistor that's built into the wire harness and a second wire with no external resistor in it from the crank lug.
You would get a hotter spark when you are starting that way.
Check first though, there may already be a 2nd wire on the coil from the starter solenoid.
Keith
 

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