Northern Lights M643 5kw trouble shooting

My startlight does not come on and my genset engine does not start when I press the start switch.

1) 13 volts at battery connection
2) DC circut breaker reset

I have limited access, 6" of clearance above the genset, no access to nonservice side, shoehorned into lazzertte. I don't really want to pull the genset out. I can access the generator control box, but it is not good access.

Where would you first look.

Here is a NL video that explains the relays and how they are all interconnected. Maybe your start relay is broken?

Thanks for the direction. I was kind of hopeing for a "magic suggestion" but it looks like I am going to have to get a little too intimit and personal with my genset down in my lazzertte.

grahamdouglass said:

2) DC circut breaker reset

Click to expand...

Did you just press the reset button? A common issue is that circuit breaker malfunctions. Disconnect the spade terminals from it and connect them to a 15 amp ATC type blade fuse and see if it works.

Does the starter turn the engine over when you try to start it ?

Does it "click" when you turn the key over? ("Can you hear the start solenoid?")

I took the remote from the lower stearing station and moved it to the genset to eliminate any harness issues. When I pressed the start button I didn't hear any sound, not a click, thunk or thank you from my genset. So I thought I might go home, watch some Northern Lights videos, (thank you W8N4SUN), and study my manual.
I'll try the "magic suggestion" with the breaker. (thank you Porgy) Once I understand the circut a little better I might try using jumpers till I get a light.

If you have access to the six screws holding down the lid cover for relays AC / DC and circuit breaker you can test your breaker for power with a DC voltage meter.

Well I just took some training from NL (see link below to TF post about this) and there are five quick things you can do to check.

1. Check oil pressure from control panel
2. Check temp if over 200
3. Check voltmeter for battery
4. Touch the muffler if hot sea water pump is off
5. Check to see if it’s getting fuel
6. Check breaker on unit (Although I don't know that the 643 has a breaker, but if it does, it's marked "fuse.")

Sounds like you have done those. (or they don't apply)

There are some lockouts in the start process to protect the engine. There are relays inside the control box that have to work. You should have a spare on hand.

Before you call NL, check the battery and starter connections. If they are loose they will still read 13v, but not be able to deliver enough oomph to flip the solenoid. (also check the connections because if they are the problem, you feel like an ass that you didn't check it first. - ask me how I know)


https://www.trawlerforum.com/forums/s6/northern-lights-training-available-55815.html

I did the same thing.
I made a new harness and we then could not get it to start.

A wire had broken in the new wire loom.

We pulled two extra and swapped it out.

Check point to point connections.

Mine had small start panel in breaker cabinet. Started fine from there.

I had intermittent start and shutdown problems with my NL 12K. After much troubleshooting it turned out to be a bad connection in the wiring to the relays. Spent a day rewiring in the Bahamas. A lot of wires in a small space so took a lot of pictures and made sketches. Have not had any problems since. The relay sockets are unique but I was lucky to have a few spares. The attachment helped.

Relay socket and connectors:

I came across a shorter version of the DC Logic video. It is 9 min vs 28 min suggested above. Both are very straight forward to the point videos.

grahamdouglass said:

I came across a shorter version of the DC Logic video. It is 9 min vs 28 min suggested above. Both are very straight forward to the point videos.

Click to expand...

So I went down to the boat with great hopes of a good resolution.
I have 6” of access above the control panel, and 1” of access between the control panel cover and the nonservice side insulated enclosure. 45 min later I had the control panel cover off.

I had 13volts at the circuit breaker which I replaced with a blue seas. I measured 13 volts at the back of the start switch on the control panel. 13 volts at the back of the preheat switch on the control panel.

I swapped out the preheat relay and start relay and cleaned the terminals. I measured continuity at the main fuses.

The start light does not come on.

Tomorrow I will phone Northern lights

grahamdouglass said:

So I went down to the boat with great hopes of a good resolution.
I have 6” of access above the control panel, and 1” of access between the control panel cover and the nonservice side insulated enclosure. 45 min later I had the control panel cover off.

I had 13volts at the circuit breaker which I replaced with a blue seas. I measured 13 volts at the back of the start switch on the control panel. 13 volts at the back of the preheat switch on the control panel.

I swapped out the preheat relay and start relay and cleaned the terminals. I measured continuity at the main fuses.

The start light does not come on.

Tomorrow I will phone Northern lights

View attachment 116814

Click to expand...

All the shutdown circuits are on the non service side of the genset. Moving around my 400lb genset in my lasarette is something I would rather not do. I’ll see what Northern lights has to say

Just to confirm, you are holding down the preheat button prior to, and during starting...

Yes, I held down the preheat button and then pressed the start button. No red light. I am no longer using the wiring harnes to my lower helm station. I am plugging into the generator, by passing the harness extension to the lower helm.
I have 13V at start circut on the control panel and 13V at the preheat circut at the control panel.
I have taken out the start relay and preheat relay, cleaned the terminals and switched them around.
I'm thinking if one of the sensors has broken then that has to be investigated, but it is on the non service side and I will have to pull the genset.

Some of these have a 12v breaker in the control box that fails due to vibes. Need to sniff around inside the box with a volt meter to see where power is and where it is not.

I was trying to visualize this. My NL, I could not remember getting a light, then it occurred to me that you probably had a different panel. Mine has the multiple gauges and I watch for the oil pressure to come up, don’t have a light but the circuit is the same.

The two most likely culprits in my mind are the oil switch and/or the exhaust overheat, and also a water temp switch. Of those, the exhaust overheat switch is probably the most delicate.

There is a circuit that connects all three with a small grey wire. If any of those switches are grounded, no workie. You can defeat each/all of them by removing them from the switch and wrapping some tape around them. Start with the exhaust, it’s a little round device that screws into the outboard side of the exhaust elbow, the wires may run up into,the control box. The water temp switch is near the heat exchanger bundle opposite end from the exhaust. The oil,switch I don’t remember, but if you follow,the wires from the water temp it should be in series with it. Remove them from the circuit one at a time to prevent grounding until you find the culprit. Then replace that switch. These are the circuits that protect the engine, so don’t defeat them or run without them (you will often see the wires clipped on the exhaust switch).

I have the same model NL and if I understand the way the start sequence works is depressing the preheat button causes the relay on the oil pressure sensor to close allowing the glow plugs to be energized, fuel to flow, and the starter to be engaged. I don’t think the temperature sensor prevents starting. The 673 manual explains the function of each relay. Since it seems the sensors only detect conditions that cause the generator to shut down when running, I don’t see how they prevent it from starting the exception being 0 oil pressure which is why the preheat switch uses a relay to effectively bypass the sensor when the preheat switch is closed. Once the generator starts and oil pressure comes up, the relay is energized and the generator keeps running.

If the DC breaker on the generator is not tripped, the only thing it could be is the preheat switch is bad or the relay that disables the oil pressure sensor is bad. All the relays are the same and generally available at NAPA (I got one at NAPA in Sitka).

Hi, Does any of you know who made a diesel engine for this NL generator?

NBs

The way I read the schematic, the oil switch(not sensor) is simply normally closed. When you depress and hold the start button, the engine try’s to start. It’s when you let up off the start button that if any fault conditions are present (and grounding), the engine immediately shuts off. The oil switch is naturally grounded and opens when it sees pressure, thus removing the ground fault by virtue of having oil pressure. Depressing the start button does not trip the oil switch, it simply bypasses the entire fault circuit momentarily.

At least, that’s how I read the schematic this morning before my first cup of tea.

I believe it’s a Shibaura block.

It looks like I am going to have to move my genset to get to the non service side. Then I can trouble shoot all the ground connections and shutdown circuts. This does not sound like fun.

Can you get to the top? Two of the three are easily reached, can’t recall the oil switch location.

Have you slapped an amp meter on the genset battery and a volt meter? If you have no click either the battery is dead OR you are not energizing the starter solenoid. I would really just check the battery first. Do you see the battery voltage drop when you turn on the glow plugs? Does it drop below 10V? Is there a fuse or battery switch between the battery and the generator?

I would confirm you have 12+V between the starter soleniod (+) and the ground point on the chassis (-).

If your battery is dead dead it may not even get the starter soleniod to engage or the soleniod is bad. Easy to check by looking at battery.

If battery does not see a voltage drop when you engage the pre-heat then you likely got an issue in the DC starting circuit. There is one logic loop for pre-heat and a separate one when you hit the start switch that runs through several sensors.

Hope this helps.

Had a similar problem with my Northern Lights. Dead dead. No click from the starter solenoid or anything. Had 13 volts at the battery and zero at the heavy red power cable on the back of the starter. There is only one thing between them and that is the battery disconnect switch. Those can go bad. In my case, I had accidentally bumped it when prepping for a trip and it was barely off of the On position. Embarrassing but an easy fix. You've already done a lot to troubleshoot. Have you verified there is power to the back of the starter motor? If there is, you should be able to hook up a jumper switch and at least get the starter to engage. That would eliminate that possible issue.

JohnEasley said:

Had a similar problem with my Northern Lights. Dead dead. No click from the starter solenoid or anything. Had 13 volts at the battery and zero at the heavy red power cable on the back of the starter. There is only one thing between them and that is the battery disconnect switch. Those can go bad. In my case, I had accidentally bumped it when prepping for a trip and it was barely off of the On position. Embarrassing but an easy fix. You've already done a lot to troubleshoot. Have you verified there is power to the back of the starter motor? If there is, you should be able to hook up a jumper switch and at least get the starter to engage. That would eliminate that possible issue.

Click to expand...

You might check the diodes that connect between a couple of the relays. You can see them in the picture on the video. Leads from the diodes are solders to wires and then connectors. Leads occasionally break at the diode. I have replaced two over the years.
Unfortunately, difficult to get to. No way to really ohm out the diodes without removing them from the relays and that is tricky.
See what NL suggests. Their techs are helpful regardless of the age of your unit.

Be wary of no load voltmeter readings

As stated before, one of the first things I did when trouble shooting my genset was to measure the voltage at the battey connections at the generator. My Fluke T5 multimeter measured 13 volts. But that was 13 volts with no load. When I put a simple circut tester across the terminals the light did not go on. There was no current.

How could this be? A good example is the windless that does not work despite showing voltage. It happened to me, and what it was was a loose connection at the sampson post. At no load there is no resistence so current flows when a load is applied resistence builds up at the bad connection preventing current to flow.

In the presenet case, even after cleaning and polishing the terminal connections at the battery I couldn't get loaded voltage at the genset.
To test the genset I moved the battery to the generator in the lazeret and hooked it up with short cables. The genset works fine.

I don't know why these 1/0 copper cables, 17.5 feet long did not carry current after doing so for 40 years. Mabey they are just tired. The last 5 feet of these cables are unreachable, they can't be pulled out and are covered by spray insulation.

I'll just replace the cables and carry on.

What grahamdouglass, JohnEasley, and ScurvyDog said - none of the sensors you mention will stop the engine from cranking. if not cranking you have electrical problem. my experience is loose connection somewhere, likely ground if this happened suddenly. Before you do anything like move the Genset make sure you have tracked the DC voltage from battery to starter motor and back to the battery, it's a round trip or nothing. closed circuit under load can give a wildly different voltage too.

Don't fixate on the pilot light, it may or may not kill the start sequence. Leave the expensive sensors alone. Yes, you have a Shibura engine.

One trick is to use a laser thermometer (pyrometer) to look for high temperature connections which denote high resistance.

If I was a gambler, I'd lay money on a bad ground wire.
Good luck to find the gremlin.
Richard

Vicem 58 Classic (for sale)
Branford, CT