1939 Pickup Wiring

[ktgarcia]

I have been trying (unsuccessfully) to figure out my wiring for the ignition switch. One side (BlackRed) goes to Resistance Unit and does not show power until the switch is turned on. The other side (BlackGreen) goes to the gages. My wiring sheet indicates that the BlackGreen side connects to the top side of the fuel gage which has the brass strip going to the oil gage. The YellowBlack wire for the oil gage goes to the sending unit. The Yellow wire in my harness I have connected to the bottom side of the fuel gage. When I connect my battery, the oil gage goes to 50 psi with the motor not running which means to me that there is power in the gages that shouldn't be.
Have I got something hooked up incorrectly at the switch that has power to the gage (oil)? It would seem to me that the gages should not have any power to them until the switch is turned on like the BlackRed (coil) side.
Could the switch be bad inside where the triangular contacts are?
Any advice is appreciated and thank you for your input.

 

[JSeery]

Your Yellow/Black wire to the oil sender unit should be a Black/Yellow wire (may be the same one and may not!). You are going to have to get a tester of some type to check out the wiring. A simple probe that lights up when there is current or a voltmeter.

Start by disconnecting the Black/Yellow (or Yellow/Black) wire between the Oil Pressure Gauge and the Sending unit (so you protect the gauge). Now connect the battery and check for power at the ignition switch. With the switch off, there should be power to the Yellow/Black terminal (Yellow/Black is normally power) and nothing to the Black/Red terminal and the Black/Green terminal. If there is power to either one of these then the switch is the problem. With the switch on, all three should have power on them.

If the oil pressure gauge is still ******* then there is a short circuit somewhere in the gauge or it's mounting. If everything checks out with the Black/Yellow Oil Pressure Sender wire disconnected, then this wire is incorrect and a power wire.

If you do not know how to test this with a voltage tester I can post some additional information.

Edit: My guess would be it is not a bad ignition switch, a bad switch allowing power to the gauges would not peg the oil pressure gauge. The most likely cause is an incorrect wire connected to the sender side of the gauge or a shorted wire or the gauge itself on the sender side.

 

[51504bat]

i recently converted my '39 p/u to 12 volts and went with a key start ignition switch. i still have the original ignition switch that was working when i removed it. Not sure if yours is bad but PM me if your interested in the one i have.