CONTINUOUSWAVE

[Seeks] a wiring schematic for a [1967] Mercury 35-HP outboard engine. The engine serial number is 2155647. The external harness and internal harness are all good, but I seem to have a dead short somewhere after the internal harness.

I hook-up the battery red to positive and everything I touch with the test [lamp] shows open.

Also, what is the purpose of the three terminals on the side of the engine?

I think they are choke, power, and starter solenoid. Thanks for any help or suggestions.

A detailed electrical schematic diagram of an outboard engine is generally only provided by the manufacturer in their service manuals. Finding an OEM service manual for a 1967 Mercury engine will be difficult. It may be simpler to just trace the wiring of the engine you have and make your own diagram of the circuitry.

I am familiar with electric circuitry and the location of faults in such circuitry, but I don't understand your narrative of your diagnostic methods with a test lamp. I give some general advice on how to proceed with diagnosis of electrical problem in an article in REFERENCE. See

Electric Starting Circuits
http://continuouswave.com/whaler/reference/electricStart.html

and read the section under the heading "Electrical Diagnostic Technique."

Circuit faults in which power distribution circuits are faulted to ground can be difficult to find. One method is to use a very good digital Ohmmeter with resolution to several hundredths of an Ohm. By careful measurement of the resistance of the fault on the power distribution circuit to ground, you can look for the absolute lowest resistance portion of the circuit. The fault should be physically nearest that area.

Since power distribution circuits often have many branch circuits, another method for fault location is to temporarily disconnect, one at a time, the many branch circuits from the primary circuit, looking for the fault to disappear. This method also works well to locate what branch circuit contains the fault.

To deduce the purpose of the three terminals on the side of the engine, I recommend you follow the conductors that are connected to those terminals. See what other components are connected to those conductors. For example, to establish that one of the terminals is the circuit for controlling the solenoid, follow the conductor from the solenoid coil, and see if it is connected to one of the three terminals.