'W' Terminal on Alternator

[David435]

The port rev counter in the saloon and on the flybridge suddenly stopped working while underway on my Princess 415. Back on my berth I managed to connect the alternator signal cable from the starboard rev counter to the port rev counter and the port rev counter worked OK which pointed to a wiring fault. On inspection of the port alternator, there are 4 cables attached as follows:

1. Heavy duty Red
2. Heavy duty Black
3. Light duty Yellow
4. Light duty Brown
I disconnected the yellow cable as it was a spade fit and on starting the engine found the battery non charging alarm operating so assumed that the brown cable was the 'W' terminal feeding the rev counters. I assume this brown cable must go into the loom and split at some point to provide separate signals to the lower and upper rev counters. Rather than trying to trace the fault through the wiring loom, would it be possible to rewire the 'W' terminal with cables that go directly to the signal input on the back of the rev counters?
Alternatively is there somebody out there who knows where the 'W' signal might split to the lower and upper helms so I can check the connections involved.

 

[volvopaul]

The port rev counter in the saloon and on the flybridge suddenly stopped working while underway on my Princess 415. Back on my berth I managed to connect the alternator signal cable from the starboard rev counter to the port rev counter and the port rev counter worked OK which pointed to a wiring fault. On inspection of the port alternator, there are 4 cables attached as follows:
View attachment 99026
1. Heavy duty Red
2. Heavy duty Black
3. Light duty Yellow
4. Light duty Brown
I disconnected the yellow cable as it was a spade fit and on starting the engine found the battery non charging alarm operating so assumed that the brown cable was the 'W' terminal feeding the rev counters. I assume this brown cable must go into the loom and split at some point to provide separate signals to the lower and upper rev counters. Rather than trying to trace the fault through the wiring loom, would it be possible to rewire the 'W' terminal with cables that go directly to the signal input on the back of the rev counters?
Alternatively is there somebody out there who knows where the 'W' signal might split to the lower and upper helms so I can check the connections involved.

Brown is warning light bulb spade terminal .D
The remaining one is rev counter feed W

yellow is battery sensing wire , without it connected to the battery plus the alternator won’t charge therefor no output for the rev counter so make sure it has a plus feed .

W is rev counter feed , it Splits upper and lower at the Y connector of the 16 pin dash loom

Looking at your pic the rev counter wire terminal has no wire on it , that’s the rev counter feed it has a 7 mm nut on it as it’s a smaller thread than the earth cable , the brown should have a spade terminal not the ring that you have when original.

id suggest you buy a handbook with the loom diagram and colours .

 

[David435]

Brown is warning light bulb spade terminal .D
The remaining one is rev counter feed W

yellow is battery sensing wire , without it connected to the battery plus the alternator won’t charge therefor no output for the rev counter so make sure it has a plus feed .

W is rev counter feed , it Splits upper and lower at the Y connector of the 16 pin dash loom

Looking at your pic the rev counter wire terminal has no wire on it , that’s the rev counter feed it has a 7 mm nut on it as it’s a smaller thread than the earth cable , the brown should have a spade terminal not the ring that you have when original.

id suggest you buy a handbook with the loom diagram and colours .

Thanks for your information. I will double check the wiring on the other alternator as that's working OK to see the difference in the connections. I'm back down to the boat tomorrow so hopefully it will be a quick fix. Could you please advise where the Y connector on the 16 pin dash loom might be located as a loose cable would be an even quicker fix.
Thanks a lot

 

[volvopaul]

Thanks for your information. I will double check the wiring on the other alternator as that's working OK to see the difference in the connections. I'm back down to the boat tomorrow so hopefully it will be a quick fix. Could you please advise where the Y connector on the 16 pin dash loom might be located as a loose cable would be an even quicker fix.
Thanks a lot

Ah what engine is this in a 415 as stated , just a thought as the alternator doesn’t control the Rev counter , you have a separate magnetic pick up on the timing case that powers the Rev Counter .

 

[volvopaul]

Is engine a 63p can make it out from the pic, if so alternator doesn’t control Rev counter

 

[David435]

The engines are TAMD63L, 318hp

 

[volvopaul]

The engines are TAMD63L, 318hp

Same as 63p , you will find a sensor in area of fuel filters on timing case .
where is your boat ?

 

[David435]

Hayling Island.

 

[David435]

Same as 63p , you will find a sensor in area of fuel filters on timing case .
where is your boat ?

I found the sensor, disconnected it and sprayed with electrical cleaner but the rev counter is still not responding so assume the sensor is not working properly but have no idea how to check this. The replacement part no is 862251 and the best price I can find is £200. You mentioned in a previous post that the alternator had a 'W' feed so am wondering if it would be possible to run a new cable directly from the alternator to one of the two signal inputs on the back of the rev counter? Alternatively does anybody know another part that could be used as an alternative or even a second hand part from an old engine.

 

[volvopaul]

I found the sensor, disconnected it and sprayed with electrical cleaner but the rev counter is still not responding so assume the sensor is not working properly but have no idea how to check this. The replacement part no is 862251 and the best price I can find is £200. You mentioned in a previous post that the alternator had a 'W' feed so am wondering if it would be possible to run a new cable directly from the alternator to one of the two signal inputs on the back of the rev counter? Alternatively does anybody know another part that could be used as an alternative or even a second hand part from an old engine.

Swap the sensors from other engine to test

 

[David435]

Due to Covid19 it has taken a long time to complete this thread. Swapped the sensors over as suggested and the rev counter worked OK which confirmed the sensor was U/S. Purchased and fitted a secondhand sensor and both rev counters now working as they should.