Adding new controls to a 1978 Mercury 1400

[gclark]

I’m working on restoring a 1978 Glastonbury with a Mercury 1400 (140 HP) outboard and need new controls. I have read that there is an adapter to go from the 7 pin harness on the motor to the new 8 pin controls. Has anyone done this and if so, how did it work? Any info at all would be appreciated.

 

[Chris1956]

That old motor should have the quick disconnect on the lower cowling. I would be surprised if you find that on a new control.

Adapting the wiring is easy, as the functions are the same (wire colors different), with the 8th wire being an overheat alarm, however, I expect you will need to graft the wiring, reusing your quick disconnect plug, or hard wiring the motor.

You will need to make sure the ign power in the new controls is routed back to the motor. It should be, but your engine needs ign power to have spark, so it is essential for you.

Usually the new control will have a purple wire which is the ign power wire. The ign killer wire (usually black/yellow) is unused in your application.

On a related note. You might inspect the engine wiring harness. Unless it has been replaced, they usually are loosing their insulation by now. That is very bad for expensive ign components.

 

[gclark]

Thanks Chris 1956! I have one more question. In my research last night, I ran across this. Would this help?

 

[Chris1956]

That looks to be the adapter from quick disconnect to the cannon plug on newer Mercury wiring Harnesses. If your new controls have the cannon plug that can make it work, if the engine wiring harness on the motor is good.

As I said in my last post, if the engine wiring harness is original, it probably is shot. If it is shot, I would recommend you buy a newer Mercury engine wiring harness with the cannon plug, and use that. You will need to wire it a bit differently than the instructions say, as your motor is battery-power cdi ignition, but I would think it will work, provided the ign power wire is present in the new wiring harness.

I can provide the wiring connection info,if you need it.

 

[gclark]

That looks to be the adapter from quick disconnect to the cannon plug on newer Mercury wiring Harnesses. If your new controls have the cannon plug that can make it work, if the engine wiring harness on the motor is good.

As I said in my last post, if the engine wiring harness is original, it probably is shot. If it is shot, I would recommend you buy a newer Mercury engine wiring harness with the cannon plug, and use that. You will need to wire it a bit differently than the instructions say, as your motor is battery-power cdi ignition, but I would think it will work, provided the ign power wire is present in the new wiring harness.

I can provide the wiring connection info,if you need it.

Any information you can provide would be great!! Thanks in advance for your help!!

 

[Chris1956]

OK, I will assume that the new controls and new engine harness have the new wire colors. They are pretty standard.

New wiring harnesses have separate battery cables. Positive battery cable connects directly to starter solenoid and negative battery cable connects to lower cowling, on your motor

Smaller engine harness wires:

Red is battery power; connect to the rectifier + post and switchbox red terminal I would jumper it to the positive battery cable as well.

Black is battery negative (ground)(if used). Connect to lower cowling.

Yellow/red is starter solenoid primary. Replaces yellow wire on small terminal of starter solenoid

Yellow/black is choke solenoid. Replaces grey wire on choke solenoid

Grey is tach signal. Replaces brown wire on one of the AC posts of rectifier

Purple is ignition power. Replaces white wire. Connect to white terminal next to red terminal of switchbox.

Black/yellow is ignition killer wire. Unused on your model.

Brown(or tan), brown(or tan)/blue are likely temperature sender wires, unused on your motor

That should do it. Best of luck as you may need to extend some of the wires, or be creative in your routing.

I would connect red wire to solenoid, switchbox or rectifier, wherever it fits best, and make jumper wires to the other destinations. Make sure the jumpers makes good connections.

It would be best to buy a harness designed for an inline six, with ADI ignition, if you can find one with a cannon plug. If not I would get a cannon plug harness for a V6 and hope it can be used without modification.