Electrical outdrive wiring

L

Loyd Dinneen

Active Member
Jul 29, 2017
484
Las Vegas
Boat Info
1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
Engines
Twin 470 Mercruisers
Omg tried to install another outdrive panel switch assembly and just like the original it didn't work. Bottom buttton lowers the outdrive fine but the top up button and the center in and out button doesn't work. You can bypass the switch and the up and down of the outdrive works but as far as I can see the in and out center operation is a no go. Haven't fully tested the switch for contiuity a project for tomorrow. Now the real clincher is I checked the wiring at the pump and what I found gave me a few more gray hairs there is a few burned up wires with no insulation coming from the harness and elsewhere and going back behind the engine and to the outdrive. According to the manual the trim sensors at the back are also screwed up as both gages are pegged up. Oh and also the pump is leaking oil that I will also look at closer tomorrow hope it is only a loose fitting. It seems that when ever I fix something on this 1977 240sda something else pops up. Good news I do have a wiring schematic for the outdrive assembly. Some day I will get it in the water and go fishing.
 
According to the manual the trim sensors at the back are also screwed up as both gages are pegged up.

There is a trim sender that operates the trim gauge, and there is a trim limit that limits the "up" travel Once that limit is reached the trim button disconnects and the trailer button must be used to raise it the rest of the way
Do you have 1 solenoid or 2 solenoids on the trim pump?

 
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It only has one solenoid on the pump. I have twin engines and it's the port outdrive that is acting up but both trim gauges are pegged. The purple and blue and white wires coming off the harness to the limit switch by your diagram are the wires that I can see are the burned up ones. I don't know whether that will effect the switch and it's operation or not but can't do it any good for sure. I'm going to test the switch today plus see where the leak is at the pump. This boat was owned by some hispanic people before, and some of the wiring and plumbing they did is beyond imagination. Is the trailer button the center button on the switch?
 
Is there a limit and trim switch on each outdrive? I can see one of the switches on the outdrive where is the other located? According to the manual you have to take the outdrive completely off in order to replace the switches but as far as I can see the one that I can see can be easily removed and by using a pull wire you can rethread the wires back through the housing and transom. Will these switches effect the operation of the outdrive in making them go up and down especially if the wires are screwed up?
 
Each hyd pump uses a trim limit switch . In most cases the insulation rots off the wires at the transom pucks. The green wire(down) goes directly to the pump motor because very little current is needed to lower the drive when under way. The up circuit(blue wire) is controled by the solenoid because of the high current needed for the motor to raise the drive underway.
THe bottom button it trim in, the middle button (when trim limits are working correctly) raises the drive to the trim limit. trailer mode is done by pressing both the middle and top buttons at the same time.
If the wires are frayed at the transom puck ,cut the black lamp wire at 16 and 17 and splice together for testing.
CAUTION this will alow the drive to raise ALL THE WAY with just the middle button.
 
I will have a look at that tomorrow. I did look at the wires at the sensors (I found them since they were right in front of my face) and looking into the outdrive it seems all the wires are bare and worn out at least the sensor on the right side of the outdrive. This also seems to be the case on the starboard outdrive also the same sensor. I'm not to concerned with gauges since I can tell the trim by how the boat is riding and the engine rpm. What I do need is to be able to raise and lower the port outdrive. If I attach the #16 And #17 wire together will that make it so as I can then use the center button to raise the outdrive? It seems like alot of work to change them out since it requires removing the outdrive and special tools. I may just get inventive and bypass the bracket that holds the one set of wires that makes it so hard. There are so many bare wires that go back there and thru the transom makes it difficult to sort them out. Thanks for all your help.
 
Loyd, with a boat the age of yours just plan on buying 2 Trim Sender Kits for your outdrives. They cost about $80 each and notoriously fail with regularity. In fact, that is why your trim gauges are not working. The sender on the right side of the outdrive is the gauge sender and the left is the trim limit switch. They look identical but are labeled as to their function and side of the outdrive. Unfortunately, changing them is not an easy job. The drive has to come off as well as the bell housing. A special tool is needed to remove the hinge pins that hold on the bell housing. Placing the puck-like senders/switch is not hard but running the wiring through the gimbal mount is the challenge. You need to follow the instructions in the kit or it can leak. And before you start thinking you'll just cut the wires and splice the new to the old wires....don't do it. The connections just don't last. (Never time to do it right but always time to do it over) It's not easy but it can be done....with a LOT of patience and a 12-pack. Getting to the bolt that holds and seals the wires as they pass through the gimbal housing is the challenge. I don't think I have done the job without modifying a tool. You will see what I mean. For the tool needed for the Gimbal hinge pins look on eBay or a local Mercruiser parts dealer. They are readily available for $7-9. Here is the link to a YouTube video on the procedure.
One word of caution. When you watch the video on YouTube there will be several others saying you can do the job without removing the drive. Don't be fooled. I watched them. One guy went on and on about how much trouble it is to pull the drive and he spent more time doing the job by not pulling it than if he had just pulled it. Also, the new senders are sealed and you cannot access the wire terminals. Besides, with the drives and the bell housing off its a great time to replace the bellows and water houses and if it were me I would also change the lower shift cable as well. With a 40 year old boat who knows when it was last done.
As for the switch on the panel you may have to just get at it with a continuity tester and see what you have . Chances are they are original and 40 years old. They are available though if you choose to replace them. I'm doing something a bit different on my Cobalt project. I've changed Throttle/Shifter control to one that has the trim selector built in to the handle. That will just control the up/down of the drive to the limits of the limit switch. To raise and lower for trailering I am using a momentary on/off/momentary on rocker switch built into my new switch panel.

Good luck. This is not a particularly difficult task. You just need patience and the afore-mentioned 12 pack.

Shawn
 
I have priced the sensors and their not to expensive, fixing them would not get me anywhere since the wires are no good. I am amazed how all those wires are so bare and the insulation is all gone. It looks like the bellows are in good shape and may have been replaced as also the hoses, not sure about the cables. All the wiring within the outdrive on the left sensor is all bare and the wiring on the right side is wrapped in electrical tape something from the previous owner most likely. This is on both units and go up through the top and through the transom, not sure if that is how it is suppose to be.
I have seen tools on Ebay to do the job and it really doesn't look that hard just will take time and bit more money. I have seen an easier way to do it but doesn't give me the chance to inspect the other areas. You right about doing it right and I am one to like for everything to work on the boat.
There is a way where you cut all the wires as close to the transon on the inside of the outdrive and then you drill a hole on the outdrive to run the wire thru and up and thru the transom above the waterline similar to what has been done with trim gauge. Splicing wires is not an option since the wires are all bare.
I have considered putting a switch on the dash but it would look odd and not original, I think my switches are good and that the problem is the sensors and all the bad wiring. For right now I will do your wire splice until I can get all the tools and parts together.
Right now I am waiting for a cylinder for my trim tabs but the seller on Ebay hasn't sent me any notes that it has been shipped and it has been 5 days already and he will not answer my messages I send, I hope he doesn't leave high and dry doing battle thru the Ebay resoluntion crap.
Anyway thanks for all your help.
 
I have been boating and working on Mercruiser outdrives for about 40 years. During that time I have seen countless attempts to shortcut the correct method for this repair. There is no good shortcut. If there was, Mercruiser would have adapted it by now. Don't drill any holes, don't splice any wires and don't try to repair the switches/senders. They will never last.

As for the bellows....unless you know for SURE the age of the bellows, water hoses, shift cable bellows and the lower shift cable, just change them now, when you remove the drives for the wiring. The water hoses could be deteriorated inside or filled with marine growth. The outdrives could have been stored in the "UP" position for a period of time and a "Set" created in the bellows and when you start moving the drives up and down the bellows could crack. A Shift Cable Bellows is a small oft-neglected item and once I chose not to replace it as it looked OK. Two weeks later I developed a nagging leak that kept my bilge pump on constantly until I finally bit the bullet, pulled the drive and replaced that little bellows. The lower shift cable is one of those items that can just start to make shifting hard. And never at an opportune time. I think the entire Bellows Kit for the Pre-Alpha drive is under $100 each and includes everything you need. Some of the kits even include the gimbal bearing. Do you know how, and have you checked the bearing for wear? Again, if everything is apart, replace all that you can at that time. You don't want to have to take everything apart 4 months later to replace something you could have done now.

BTW Unless someone upgraded them you do not have Alpha I outdrives. Merc didn't make the Alpha until 1983 or '84. You have an "M", an "MR", "1" or a "Pre-Alpha" drives. Most parts are inter-changeable but with other parts it makes a difference.

I know this all may be more money than you were planning on spending at this time but this will really save money in the long run. I have been rebuilding my 1985 23' Cobalt for 3 years now. This was going to be a 6-month project. At this point I have 2 take-aways....plan on your project taking 3 times as long as you figured and, expect to spend double what you originally planned for. Not trying to be a doom-sayer but just trying to share what I and others have learned ahead of you.

Best of luck. Ask away if you have more questions. Oh....and check YouTube for how-to videos. There are several on everything you are going to do.

Shawn
 
I will most likely pull the out drives and have ordered the pin tool off of Ebay and I did see a kit that has all the parts for the Alpha drive I will have to go down to my merc dealer with the serial # of the outdrive and see which setup I have. I figure that I will have to put another 500.00 into the boat to fix this issue, it's a good thing my wife doesn't mind and understands what boat really means.LOL
I do have another boat to use to go fishing in and as long as my neighbors don't complain about the cruiser being parked in front of my house I will just let it set there. I made sure that it only takes up the street space that my truck does width wise.Mean time I will break out the buffer and go to work on the body and try to find where the pump leak is. Need to find a fairy to get back behind there to see where it's at. LOL
Thanks again
 
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