Volvo KAD43 electrical problem.

[msimms]

Fired the port engine up for the first time in about six weeks. First thing I noticed was that the instrument warning lights (water temp, oil pressure and charge) didn't illuminate when the ignition was switched on. Turned the engine over and she started fine but the rev counter didn't operate. Gave it a few revs in neutral but no change was noted.

With the engine running I operated the trim and the rev counter immediately started working. As soon as I stopped operating the trim rev counter drops to zero. Operating trim up or down, as long as the legs moving (pump running) rev counter works. Starboard engine and electrics all work as they should.

Any idea where to start looking first? Must be a bad connection somewhere but without an electrical schematic not sure of the best place to start.

Thanks for any ideas.

Mark

 

[jparham]

I'd go looking at earthing points around your port engine. Sounds like one is loose or corroded. A high current draw through another device will 'pull down' a floating earth, hence it seems to work.
Out with your Vaseline!

 

[volvopaul]

Try the reset button on the black plastic box ontop of the engine above the raw water pump.

 

[DavidJ]

Try volvopaul's suggestion first (he's usually right!) but the problem reminds me of problems I've had in the past with old cars where an earth connection has become 'open' and the device is finding it's earth through other instruments when they are turned on. You could try attaching a long piece of wire to the battery (earth side) and then by earthing various suspect instuments you might be lucky and find they come back into life.....I hope the reset button works for you though...please report back since I have KAD43's as well

 

[A_8]

Yes, please report back. I have a ralated problem that I have not found the fix for.
Thx/Michael

 

[msimms]

Will definitely report back.

Reset switch will be the the first thing to check then on to all the earth points.

What similar problems are you having?

 

[Peanuts]

Hi
Always a differcult one to find, have you had any problems at all similar to the one you mention.
You mention about the lights not working, I don't supose you noticed (if they were switched on that is) if the instrument gauges lights were 'on', its just that they use the same earth as the RPM gauge, if they were not working when they should be and the RPM gauge was also not working it might help trace the dodgey earth problem that you probably have. I know what I mean but does this make sense to you. Would an electrical diagram help? PM on its way.

Steve

 

[A_8]

Great thanks.

Sometimes I get irratic rpm readings on the starbord engine.

When this happens and I operate the trim it comes back!

I have earthed the instruments separatly thinking along the same lines as you guys but it did not make a difference.

/Michael

 

[msimms]

Hi Steve,

Can't say I noticed whether the instrument backlights were on or not. I know they did work in the summer as I replaced all the bulbs. I'll make a point of checking them at the weekend.

As for similar problems, there was one that I'd forgotten about. In fact I can't recall if it was from the port or starboard side. If the ignition is switched on, on both engines, on one side, after about a minute the warning buzzer will sound. I think something also happens to the warning light as well but can't recall. Under normal use you never see anything untoward as you normall just turn past that position and start the engines. Before fault finding the rev counter problem I'll check if this problem still exists.

As for the electrical diagram - yes please. It will be very useful, I'll reply to your PM.

Cheers

Mark

 

[dazza2097]

Hi Micheal,
you need to be carerful with rpm readings on KAD engines, from my experiance, it is normaly the belts being loose. you can prove this by if the RPM goes down when the supercharger cuts in.

Darren

 

[DavidJ]

[ QUOTE ]

you need to be carerful with rpm readings on KAD engines, from my experiance, it is normaly the belts being loose. you can prove this by if the RPM goes down when the supercharger cuts in.


[/ QUOTE ]
Just to add a bit of detail, the RPM pick up on the KAD43 is off the compressor.

 

[msimms]

Volvo KAD43 electrical problem - Partially resolved

A couple of people asked me to report back on this problem so............

Went down to the boat today with multimeter in hand, and electrical schematic in pocket (Thanks to Peanuts for schematic) to try and get to the bottom of the problem.

Started up the engines and everything was working fine! All warning lights and rev counter working perfectly. Left engines running for twenty minutes, switched off and back on again, still all fine.

Got on with some other tasks and after an hour or so I tried the engines again, the fault was back. Engines off and back on a few times but fault remained.

Started checking through all -ve connections using B- on alternator as reference point. This connection did look a little corroded so took connections off, cleaned up and re-assembled. Measurements from B- to all connections on engine, connections in and leaving the junction box on top of engine came in at 0.1 to 0.2 ohms. From B- to batteries measurement was a little higher at 0.6 ohms. Cleaned, lubricated and tightened connections and re-measured at 0.2 to 0.3 ohms.

Tried starting engines again and fault remained.

I then tried with the shore power disconnected. Fault went away and everything back working. Shore power back on and tried again, still working fine. Engines off and back on, still good. On the third attempt fault re-appears. Tried this a couple of times. Shore power off and back on again no fault for the first two starts and then from third start fault occurs and stays.

DC negative is connected to mains earth and a galvanic isolator is fitted. Seperating DC from AC earth made no difference but switching off the battery charger solved it.

So, in summary, switching off battery charger or disconnecting shore power the fault will not occur or will clear.

I guess the answer is that engines shouldn't be started when hooked up to shore power. Even so, I'm still puzzled to why this should only effect the port engine. Next time I've got a spare hour or two I'll fault find further and see if I can determine why only one engine displays this behavior.

 

[msimms]

The rev counter is fed directly from terminal 'W' of the alternator not the supercharger.

The supercharger only engages between 1700 and 2400 rpm. There is an engine speed sensor that feeds the engine speed relay. This relay controls the the supercharger engaged/dis-engaged state.

 

[DavidJ]

[ QUOTE ]
The rev counter is fed directly from terminal 'W' of the alternator not the supercharger.

[/ QUOTE ]
Interesting, I've always thought that the rev counter signal comes from the inductive sensor (tooth counter).

 

[msimms]

If you PM me an email address I'll forward you the electrical schematic. It includes a description on the operation of the supercharger.