Re: 1972 Johnson 50ESL72C HELP!!
The key to your control unit search is to get one for a "hydro electric" motor. This is the only type that will work with your engine and it is important that you get the right one. Be aware, that there are other OMC motors with electric shift, but they are not for hydro electric models and won't work with one.
There are also hydro electric shift models that have a different ignition system than your motor does. Because of this, there are differences in the circuitry in the control box and the units for those motors can not be used on your engine. The way to tell the difference is that the older motors have a black plug on the end of the wiring harness, while the one you need will have a yellow plug.
There are two versions of this control. The Johnson unit is white and has a single lever. It also has a "Johnson Hydro Electric" decal on it. The Evinrude version is somewhat smaller in size, also has a single lever, but has push buttons on it to handle the shifting function. This is in contrast to the Johnson version, which has an internal toggle switch to provide for shifting. Either of these units will work on your motor.
Possible sources of control units for your motor are EBay and dealer/repair shop surplus parts inventories. Be careful what you buy, however, because these control units are notorious for having bad shift switches. That is most often why they are retired - the switches are NLA items, so the boxes become essentially useless if they are bad.
To see the boxes that I am speaking of, you can go to
www.shop.evinrude.com. Select the tab that says "Parts" and then look for a window that gives you a "pull down" list that includes "Evinrude" and "Johnson." This list defaults to Evinrude, so select model year 1972 and then select your motor (50). That section will have subsections for the various versions of a 1972 50hp motor - pick any one of them and then look for an additional subsection for "remote control." When you open that page, you will see a parts diagram that illustrates the unit pretty well. Once you have seen the Evinrude version, repeat the process for the Johnson model.
Before you spend money on a control box, I would spend some time checking the rest of the motor. You should probably try to get it running and you should check the shift solenoids in the gearbox. I need to get onto some other things right now, but will stop back this evening to offer some thoughts on those items. I'm that, if some of the oters with knowlege of these motors see this thread, they will help too.
