Electrical fault. Advice sought

BruceK

BruceK

Well-Known Member
Joined
8 Feb 2015
Messages
8,365
Location
Conwy
Visit site
Volvo KAD 42. Took the boat out, bit rough. Anchored up in rolly water. When it came to start engines port started fine. Starboard dead at ignition. No guages nothing on Stbd. Complete electrical outage.
Common isolator switch and battery bank.
Checked fuses including trip on engine. All good.

So my thinking is no power is getting to ignition switch to kick in the gauges or starter relay. Where should I start looking?
 
Check if you have power at the alternator b+ and b- . That’s permanent live (with isolators on of course)

Loom plugs not come apart

Wires in the back of the ignition switch still connected
 
Will do. Where does the ignition switch source it's live from though and do ignition switches ever just fail without warning. (bearing in mind all was well until I switched the engines off) I'm thinking vibrations getting there and rather rolly water while at anchor may have a part to play in loosening something. It was a rounded 4 foot swell with a 3 second period. The boat was rolling badly for most of the days fishing. Lots of crew spewing in misery but the fishing was good so they soon perked up....
 
BruceK said:
Volvo KAD 42. Took the boat out, bit rough. Anchored up in rolly water. When it came to start engines port started fine. Starboard dead at ignition. No guages nothing on Stbd. Complete electrical outage.
Common isolator switch and battery bank.
Checked fuses including trip on engine. All good.

So my thinking is no power is getting to ignition switch to kick in the gauges or starter relay. Where should I start looking?
Click to expand...

Pop fuse side of black electric box , has a live and earth one , either blown will cause your problem
 
Not sure if the electrical setup is the same as the kad 44 but it seems to have the same black box on top of the engine. My kad 44 had a broken retaining nut on the cable going into the black box. The slightest nudge would disconnect the connector and cause a dead engine. This would not be visible by looking at it. I would try the wiring loom connections first starting with the one on top of the engine. Might be a simple fix with a cable tie.
 
Well Bruce, where to begin?

The beginning is a good place so the batteries would be my first port of call and the terminals are always first as they can corrode or become loose, but look fine.

These cables run to some form of electrical distribution board so check this next to confirm power, if it has power you have eliminated this section of wiring.

From here you will have wiring running to the ignition switch so find the live terminal on the ignition switch and check power is going to it, if not it is this section of wiring. One simple test would be to run a live wire from the distribution board to the ignition switch and turn it on and see if your lights come on, this will confirm it.

If you have power to your ignition switch you can test it by probing each position as someone turns it to each position and test for power at each outlet, if you have a live feed and no power out it confirms your ignition switch as these do go wrong more often than people think. Bosch units used to wear the thin brass contact strip out and they used to snap off inside the switch.

Fuses and breakers need removing and checking with a continuity test and not a simple visual check as many fail but look fine in the viewing area, so pull them and continuity test on them, and check for condition.
 
rlw said:
Not sure if the electrical setup is the same as the kad 44 but it seems to have the same black box on top of the engine. My kad 44 had a broken retaining nut on the cable going into the black box. The slightest nudge would disconnect the connector and cause a dead engine. This would not be visible by looking at it. I would try the wiring loom connections first starting with the one on top of the engine. Might be a simple fix with a cable tie.
Click to expand...

+1 connector on an engine loom having jiggled loose would be my first call.
 
volvopaul said:
Pop fuse side of black electric box , has a live and earth one , either blown will cause your problem
Click to expand...

Hi Paul. The pop fuse themselves, are they liable to break? That was my first thought and I checked it by pushing in but either it was already in, made no difference or was stuck permanently out. Difficult for me to tell as the button / shaft is black all along the visible length. I presume a continued short would hold it tripped but I did not feel any sort of click to signify that.
 
Assassin said:
Well Bruce, where to begin?

The beginning is a good place so the batteries would be my first port of call and the terminals are always first as they can corrode or become loose, but look fine.

These cables run to some form of electrical distribution board so check this next to confirm power, if it has power you have eliminated this section of wiring.

From here you will have wiring running to the ignition switch so find the live terminal on the ignition switch and check power is going to it, if not it is this section of wiring. One simple test would be to run a live wire from the distribution board to the ignition switch and turn it on and see if your lights come on, this will confirm it.

If you have power to your ignition switch you can test it by probing each position as someone turns it to each position and test for power at each outlet, if you have a live feed and no power out it confirms your ignition switch as these do go wrong more often than people think. Bosch units used to wear the thin brass contact strip out and they used to snap off inside the switch.

Fuses and breakers need removing and checking with a continuity test and not a simple visual check as many fail but look fine in the viewing area, so pull them and continuity test on them, and check for condition.
Click to expand...

Thanks for the time to write that Assassin. I'm guessing I am going to have to do these tests. Half my problem is finding these looms. It seems they were put in the boat before the various shells and topdeck and I have tried to trace them before without much luck. From the back of the engine they simply disappear into one of many loom carriers to reappear behind the dash. No connectors to be found.
 
simonfraser said:
+1 connector on an engine loom having jiggled loose would be my first call.
Click to expand...

Black multi-plug on end of loom at engine should be a twist and lock.
It is made out of plastic and can get very brittle. Plug on my port engine gave up the ghost.
Trod on cable.
All Works perfectly OK but actual locking ring nackered
Now secured with cable tie.
+1.
 
thanks for the heads up. :encouragement:


On another note. Looking at the wiring diagrams for my boat, there is a tilt sensor. Supposed to kickoff at 90 degrees or something. We never reached a 90 degree roll but we would have been rolling quite considerably at times and in the short period swell quite a lot of momentum on the reversal on the back side of a swell. On the very remote chance one of these kicked off can anybody opine as to where it's located?
 
You're welcome Bruce, this is why you spot test at various points, so you identify sections and eliminate them and locate the correct section.

Much easier to work on a section than the whole loom.
 
On my throttle levers reverse gear can look like neutral. Small movement. Trying to start in reverse caused the engine management box fuse to trip. Thats new to me?? Must be a thermal fuse because when I checked it it did not have a positive click and then jump out again so I presumed it was good. Got back to the boat, pushed it. It clicked back in. Voila.

Volvopaul right on the money as always. Didnt think starting in reverse should trip it though. Very odd. I suspect there may be a deeper issue that needs investigating
 
You must log in or register to reply here.

Share this page

Top