A tale of Engine Harness Maintenance - 87 mkII

Jun 2, 2014
602
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
I've already posted about parts of this in other threads, I just thought I would share the entire experience for anyone else interested. This isn't an ask for help, I've pretty much completed my project for now. I know that some will find this helpful because I really didn't find much information on my setup being that it's a later model setup than most of what's posted here.

It started with an oil pressure beeping issue. I recently had very quiet beeps out of the sounding device at the cockpit control panel while underway, but couldn't figure out any issue with my oil pressure. I changed the pressure switch and tested it with a pressure gauge to confirm it was good. It was. First off, the pressure switch is just that - an ON/OFF SWITCH. It shouldn't be able to provide a slightly resistive connection to ground to make the beeper quietly beep.
1657555335306.png


So, why was it mysteriously beeping? A few people here suggested looking at the wiring harness. Now, I bought the boat in 2014 from basically the original owner and it's an 87. Most of the upgrade info on the older boats was already done on these or the PO did it already. But I knew that it still had the old trailer connectors. I've read the available information on the connector issues, but since I shouldn't have any high-current flow through the harness (I have the Volt meter on my panel already), maybe the connectors just need to be cleaned or something. Little did I know how MUCH corrosion happens in there, and how much damage they can do to themselves. But even before inspecting them, based on my issue that it MUST be a wiring issue, I decided it was a good idea to just replace the connectors at the engine and all of the wires going to the engine.
I made a box with a marine terminal block inside it. My plan was to replace the trailer plugs with this.
Another issue I had were wiring diagrams. Even in the on-board manuals set I had on the boat, everything was the same generic manual with the same wiring diagram:
1657555523291.png

The problem for me was that it was hard to understand since I didn't have an Ammeter (both diagrams show an ammeter) and I didn't quite understand what all the alternator wiring did. So a diagram that wasn't exact was very confusing before starting this project. I did finally find some diagrams that matched my setup in what used to be the upgrade instructions from the old setup to the new setup. These diagrams made a lot more sense, and matched what I had already. I could now understand the wiring I had.
1657554937808.pngCatalina Harness Connector Upgrade Wiki
So, I started the process. Man, those trailer plugs were BAAAAAD... The connector was nicely taped up and zip tied so it looked good from the outside, but when removing the tape and zip ties, this is what I found. The connector was split literally from corrosion exploding it from inside.
1657556098273.png

I'm pretty convinced at this point this is why the oil pressure beeping would happen without the switch involved. Made sense now.
I also had intermittent starting issues for quite some time, where you'd have to press the starter button a few times to get it to kick over.

While wiring it all together, I found this piece of info in the harness upgrade instructions:
1657556258101.png

It said the orange wire should no longer be connected to anything. Wait a sec, I thought... I have an orange wire connected to the alternator! I'd better wire it like it says in these instructions! Thinking I'm doing something good, I make a nice red jumper to from the Alternator to the Starter.
1657556454464.png


After a visual inspection, I tested the the engine, and it started right up. Interestingly, the start button works instantly without the need to press it a few times.
The oil pressure beeping also seems to behave as expected. Great! Lets move to the next harness conector... the cockpit panel!
Here's what I found behind the gauges. Some gauge connectors that should be cleaned or replaced, and a bad trailer plug again. It wasn't as bad as the engine compartment, but still not great. I didn't want to spend the time to build a box for this end, so I planned on using a standard barrier strip like in the upgrade instructions.
1657556970515.png

1657557041055.png


I took the time to label the gauge end of things, and then this is where it got weird. I wired it all back up to a barrier strip, and I replaced a few of the wires and connections behind the gauges, but when I put it all back together, none of the gauges worked!!! WTH???? What could I have done wrong???
Thinking I did something wrong, I started metering everything. It wasn't easy to figure out, because a lot of the gauge sender feeds, starter, etc all have low resistance to ground and show continuity to ground on the meter. Okay, I'm confused now. What did I do wrong?
I made the mistake of spending a late night trying to troubleshoot it all in the dark. Now the engine won't start! Wait a sec, I have gauge problems now and the engine won't run. UGGGGHHHHH! It's midnight, I'm going home, will try again in the morning.
I had dreams of boat wiring, and woke up thinking about what could be wrong. Then I realized that I don't remember seeing a wire in the engine compartment for the tachometer. Where was THAT? So, I decided to start there for the day.
Looking at my gauges, there is clearly a light BROWN/TAN wire that was attached to the Tach Sense input of the gauge. Where is the other end of this wire? I don't see it. While I'm down by the engine I happen to test the always-connected bilge pump that usually buzzes outside at the cockpit panel. Hmm, that doesn't work now either. What is going on???
So, looking around I discover that the bilge buzzer was using an orange wire. Wait...I disconnected an orange wire from the ALTERNATOR? Ah ha, there's ANOTHER orange wire down there, and I disconnected it thinking I don't want any orange wires going to the cockpit panel because all the wiring diagrams show the orange wire being used for Ammeter stuff. I realize that the bilge buzzer used one of the TWO orange wires that were bundled in the engine harness. Okay, got that figured out.
But what about the tachometer?? I CANNOT find any tan or brown wire going down to the engine area except for the TEMP sense wire which I have already verified. But there is this second Orange wire that I cut from the alternator and replaced it with a red jumper to the starter. Could it be that? Oh crap, yes, that must've been the tach wire?? I made a test jig to test tone out the wire and sure enough, that brown/tan wire at the tach gouge somehow becomes orange in the engine compartment.
Needing a new piece of wire for the engine compartment, I went to WM to find something tan or grey in 12-14 gauge. Nothing. But they have ORANGE! Damn. Okay, well, I guess I'm putting back the two orange wires I thought I didn't need as orange wires again. LOL.
I un-fixed the red jumper and reconnected it to the orange wire that I now know is the tach input.
Okay, everything together now, trying to start the engine, still won't run. WHAT DID I DO??? The starter kicks over and I can hear the fuel pump, but it won't run. Jeez. I take a break for some In-N-Out and start looking online for ideas. Reading about diesel engines, I saw the word "stop solenoid" and I was like, "wait a sec... the kill switch!!" Feeling really stupid now, I go back to the boat and happily push the kill switch handle down which in my defense didn't notice since the gauge panel was now in FRONT of it, and I had just spaced out about it.
Now the engine runs perfectly again, my tachometer works, my volt meter works, and my temp gauge works, but NOT the fuel gauge. Hmm.
Okay, so lets check the sender wire. I know it's the blue one. I open the fuel tank hatch cover, remove the wire, meter the sender. 63 ohms. Okay, put the wire back, go back to the cockpit, measure there, 63 ohms. From what I read about the gauge online, it's suppose to operate between 240-33ohms. Dead short should show FULL and an open should show EMPTY. That's all I see is EMPTY. To make sure, I pull the gauge out, connect it directly to the battery and try shorting the sense input, nothing. I call West Marine and they have a black or white one with the same specs. White sounds fun but I'd have to replace all the gauges or it'll look stupid, so I pickup the black one. I install it, and it works perfectly. Now everything works, and all the trailer plugs are gone.

The thing that threw me was that I "extra-fixed" the alternator wiring making the tach stop working, and I had a failed fuel gauge, so it seemed like I had bigger problems than I did, and then compounded by forgetting about the kill switch just drove me crazy. But its all working again!

1657558497904.png
 

Attachments

Last edited:

jviss

.
Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
Wow, wonderful write-up, thank you. I', sure this will help others following you your footsteps.
 
Feb 18, 2022
440
Catalina 36 Port Orchard
Awesome write up. I had similar issues on Luna, and I went with the new harness from end to end route. Mostly because what I had was so bad it wasn’t going to be of any good. The negative lead to the instrument panel looked good on the outside, so I decided I would use it to make the negative jumpers for the new panel… well I cut it about 2 feet from one end, the copper was black and green… so another 2 or 3 feet… same thing… and again couple more feet later. So this wire (and a few others) was corroded from one end to the other.

I agree that the schematics are not good. I decided to just create my own based on my wiring knowledge. With my alternator, I do not know how it was hooked up originally, most of the wiring was cut or corroded off. Thankfully I paid attention in my auto electrical classes and knew how they worked. The sense wire (also called the field wire) goes to the alternator output, or to the battery positive (this is why yours goes to the starter) and the exc, or excite wire (also sometimes called stator wire) goes to the ignition switch. This is pretty much how any basic alternator is wired up.

Glad to see you are up and running again. I will hopefully have all my wiring done by this weekend, both the AC, DC and engine.
 
  • Like
Likes: jonelli
Jun 2, 2014
602
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
I think I'm going to go back over all the connections on everything and spray it all with a can of T-9 "boeshield" I have. I don't think it will hurt anything, and might help with some corrosion prevention prolonging things. I've used T-9 before on many things including trying it as a wax for my motorcycle, but it leaves a waxy film behind. That's why I think it'd be good for marine terminals and any exposed connections.
 
  • Like
Likes: mikeracca
Feb 18, 2022
440
Catalina 36 Port Orchard
I think I'm going to go back over all the connections on everything and spray it all with a can of T-9 "boeshield" I have. I don't think it will hurt anything, and might help with some corrosion prevention prolonging things. I've used T-9 before on many things including trying it as a wax for my motorcycle, but it leaves a waxy film behind. That's why I think it'd be good for marine terminals and any exposed connections.
Im not sure what the T-9 is, it sounds like a Terminator model… Just sayin…. I plan on caking my plugs with some good ol silicone based dielectric grease.
 
Jun 2, 2014
602
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
Im not sure what the T-9 is, it sounds like a Terminator model… Just sayin…. I plan on caking my plugs with some good ol silicone based dielectric grease.
1657641422023.png

It's basically a non-conductive oily wax that you can get in a spray can they claim was made for jets and spaceships. So, should pretty much do the job. It's also magic if you read their description of what you can do with it. lol. I just happen to have a big can of it.

I was curious if it would work on my motorcycle as a protective spray, but it really leaves an annoying visible filmy cloudy wax on everything. I went back to something called Protect-All in a spray can for my motorcycle. It dries clear and slick.