Yanmar 4JH2-HTE: Engine Harness replacement

[claptrap]

Long time lurker, but now it is time to post something myself.

We (family of 4) have been cruising well over a year now and the day before yesterday we had one of the things no one *ever* wants: the engine harness short circuited on the engine side. We were able to start the engine previous to that, but none of the controls (except for throttle) worked.

We are very lucky that nothing worse happened from it and we were able to sail ourselves out of the problem and the motor was running so we could limp into a nearby harbor.

If you want to know more on the details, feel free to PM me. Let's focus on the way forward:

The problem so far: The engine harness is proper fried, there was smoke. I need to find a new one and replace the fried one with the new one. I will also have to check the rest of the wiring from there to the panel for any damage (and am thinking about replacing it all together).

We have a 4JH2-HTE with a serial number 242XX, it was built around the late 90s. We have the (simplistic) B2-type panel with rpm gauge, indicator lights, stop switch and the starter key.

As far as I can tell from my research, we need to get either part number 129573-77932 or 129573-77931 (see here: https://dieselpartseurope.com/media/...-M35102_en.pdf, page 68) to go on the engine. Judging from the serial number, I'd wager 129573-77932.

I am having problem with understanding the parts catalogue on the panel to the engine side of things (page 72): it seems that all the extension cables (part numbers 18, 19, 26, the long run from the panel to the engine) are discontinued. The parts number I can come up with is 129470-77530.

Can someone knowledgeable of this engine chime in on how to replace the wire harness and get the engine running again?

Does anyone know a good Yanmar service shop in NJ in case we need to get external help, get the engine pulled, fixed and reinstalled again.
Right now, we're stuck in Atlantic City with an engine that cannot be started safely.

[Bycrick]

Be very careful that who you deal with knows what they’re doing. I have a 4JH2-TE, new in 1998, with a C panel. When I ordered new cables for the engine side and the extension, I discovered that none of the new cables (with square connectors) matched the original cables with round connectors. It also seems that the part numbers for the two different cables is the same. They finally gave me my money back and I built my own cables.

[Time2Go]

Contact
Mack Boring in Edison NJ
They know Yanmars
Cheers
Neil

[Time2Go]

Oops, Mack is now in Somerset, NJ

[claptrap]

Originally Posted by Bycrick

Be very careful that who you deal with knows what they’re doing. I have a 4JH2-TE, new in 1998, with a C panel. When I ordered new cables for the engine side and the extension, I discovered that none of the new cables (with square connectors) matched the original cables with round connectors. It also seems that the part numbers for the two different cables is the same. They finally gave me my money back and I built my own cables.

Thanks so much for the replies so far.

I am currently speaking with toad marine supply, they seem competent an ship to NJ.

We have the square connectors on the engine side, I'll have to get to the panel tomorrow as I'm currently working through the procedure to remove the heat exchanger and intercooler to get better access to where the cabling goes.
I will try it with the official parts first, although I am fairly confident I could build the loom myself. I am quite adept with electronics.

[claptrap]

Originally Posted by Time2Go

Oops, Mack is now in Somerset, NJ

Mack Boring would be someone we can contact if we need external help, is that correct?

[Bycrick]

The parts dealer can be just wonderful, but if you just order by engine model and part number, as I did, you might just get incompatible wires. They’re not cheap, but they simply gave me my money back. And I was dealing with a big, well known Yanmar dealer who I’ve been dealing with for 15 years. Having the older, analog panel can complicates things.

[claptrap]

Originally Posted by Bycrick

The parts dealer can be just wonderful, but if you just order by engine model and part number, as I did, you might just get incompatible wires. They’re not cheap, but they simply gave me my money back. And I was dealing with a big, well known Yanmar dealer who I’ve been dealing with for 15 years. Having the older, analog panel can complicates things.

I hear you. I will kindly ask them to somehow find out whether the loom has the square connectors (newer, I take), which our engine and panel seem to have, before I order. If they cannot ascertain that, I will make sure I can return it.

The cost of the loom is not that much of a factor as we're living on the boat full time, so the most important thing is to a) do a proper job fixing it and b) get moving again. One more week in a marina exceeds the cost of any amount of cable and connectors I need to buy or fabricate in order to repair this.

[Wotname]

Originally Posted by Mirabella

........, although I am fairly confident I could build the loom myself. I am quite adept with electronics.

The first step is to determine why the original loom fried itself!

Of course a new loom is the easiest plug and play option but...if you are competent enough, then a custom loom made by yourself will trump the built to the minimum standard Yanmar loom. I am assuming you have the Yanmar schematic - or can design it yourself.

I understand the need to get the engine going again as quickly as possible and a custom loom takes time however it can be done in stages or even some temporary wiring to get you going again.

Strip away the old loom. Concentrate on the start and stop circuitry, then charging (alternator) aspects and finally the alarm details.

[claptrap]

Originally Posted by Wotname

The first step is to determine why the original loom fried itself!

Of course a new loom is the easiest plug and play option but...if you are competent enough, then a custom loom made by yourself will trump the built to the minimum standard Yanmar loom. I am assuming you have the Yanmar schematic - or can design it yourself.

I understand the need to get the engine going again as quickly as possible and a custom loom takes time however it can be done in stages or even some temporary wiring to get you going again.

Strip away the old loom. Concentrate on the start and stop circuitry, then charging (alternator) aspects and finally the alarm details.

Thanks for the encouraging words. I have the printed service manual for the engine, so I have the full schematic for the panel wiring.
If we cannot get the OEM loom in any reasonable amount of time, my understanding is we can limp on with a temporary loom given two conditions:

- the motor can be started with the remote (stopping it manually without the remote is viable, I already did that to shut it down)
- the alternator is hooked up safe and working, pumping current into the batteries.

Then we can work on the sensors/alarms.

[Wotname]

Some people replace stuff, some people make stuff!

If you a person who is willing to make stuff, it comes down to making an assessment of your own abilities and the willingness to take on a challenge if you don't have sufficient past experience. It also helps to know you own level of acceptability quality wise. For some people near enough is good enough, some will only accept excellent quality in their own work.

A loom is only a bunch wires, terminals and interconnections - all of which are commercially available and not hard to source.

You can either reproduce a factory loom or make a custom one seeking improvements where you can, either in the quality of the materials, the placement and securing of the wiring or in the design principles.

For instance, providing there is space and a suitable location, I prefer to bring all the wiring from the various engine components to accessible terminal strips in a single location. Likewise bring the wiring from the instrument panel to the same location and perform the interconnect at that point. This makes future trouble shooting much easier and allows for any component to be easily isolated if needed. Keeping the wiring from each component seperate means you don't need to colour code the wiring (unless you wish do). Create you own schematic to reflect the wiring and terminal numbering.

Some examples, but there are probably better ways than mine!

[stormalong]

Do you know where in the harness the fault is? Just replacing the section with the connectors might not solve the problem. It is more likely to be a problem in the connector where the contacts are exposed.

I had a similar problem, different engine. I had enough slack in the harness to eliminate the connector and take the wires direct to the sensors, starter, alternator.

The purpose of the connector is just to make the installation easier and to provide the option of different length wiring. Once the engine is installed there is no benefit, just downside. The connector might get oil or worse, salt water dripped on it causing problems like the one you have.

[claptrap]

Originally Posted by Wotname

Some people replace stuff, some people make stuff!

If you a person who is willing to make stuff, it comes down to making an assessment of your own abilities and the willingness to take on a challenge if you don't have sufficient past experience. It also helps to know you own level of acceptability quality wise. For some people near enough is good enough, some will only accept excellent quality in their own work.

A loom is only a bunch wires, terminals and interconnections - all of which are commercially available and not hard to source.

You can either reproduce a factory loom or make a custom one seeking improvements where you can, either in the quality of the materials, the placement and securing of the wiring or in the design principles.

For instance, providing there is space and a suitable location, I prefer to bring all the wiring from the various engine components to accessible terminal strips in a single location. Likewise bring the wiring from the instrument panel to the same location and perform the interconnect at that point. This makes future trouble shooting much easier and allows for any component to be easily isolated if needed. Keeping the wiring from each component seperate means you don't need to colour code the wiring (unless you wish do). Create you own schematic to reflect the wiring and terminal numbering.

Some examples, but there are probably better ways than mine!

That certainly looks like something I'd like to see instead of potentially flakey proprietary connectors. I'll certainly give that option some more thought.

[claptrap]

Originally Posted by stormalong

Do you know where in the harness the fault is? Just replacing the section with the connectors might not solve the problem. It is more likely to be a problem in the connector where the contacts are exposed.

When I look at what parts look the worst after the short circuit, then the starter relay (probably, it looks like remnants of a relay) is where it started or where it had the most effect.
Our loom from the cockpit to the engine is quite long, probably the 5.8m one, which mandates the use of the starter relay due to the current required to reliably pull the starter solenoid so I'm pretty certain it is the starter relay. We also have the stop solenoid relay on the stb side of the engine, despite the solenoid actually being on port, but I guess that's as designed by yanmar.

[claptrap]

I have to decided to make my own loom. Half of the cables in the original one are not used on our engine and I'm sure I can make a nicer, more accessible connection using terminal strips.