Volvo Md7b control panel wiring.

[fishermantwo]

Have just replaced the timber for the instrument panel. While doing this I had to disconnect the wires from the back of the panel. Putting it back together was fairly simple because the leads are clearly marked or so I thought! One thick green wire with 30 marked on one end and switch on the other. The 30 is the pin 30 on the back of the starter switch. But where is the other end marked switch go to? The wiring diagram in the manual is not that helpful! Appreciate any help.

 

[Bilgediver]

Have just replaced the timber for the instrument panel. While doing this I had to disconnect the wires from the back of the panel. Putting it back together was fairly simple because the leads are clearly marked or so I thought! One thick green wire with 30 marked on one end and switch on the other. The 30 is the pin 30 on the back of the starter switch. But where is the other end marked switch go to? The wiring diagram in the manual is not that helpful! Appreciate any help.

It appears to go to Terminal B on the terminal strip adjacent to the panel then continues on to Terminal c on the alternator.

Note there are 3 green wires and this is the thick one.

 

[VicS]

A bit puzzled because the diagram you have attached shows only the incoming positive , from the fuse via Teminal C, on terminal 30.

Other green wires are the switched positive supplies to other items on the panel but coming from terminal 75.

I think maybe you have a later panel which has an unswitched supply from terminal 30 to the "extra equipment" switch ( the diagram I am looking at though shows this as a red wire ) but you would not have needed to disconnect it to remove the panel.

Either the wire in question is this latter one, but green) or it is a supply to a switch that is not part of the panel ( hence the need to disconnect it)

 

[VicS]

It appears to go to Terminal B on the terminal strip adjacent to the panel then continues on to Terminal c on the alternator.

Note there are 3 green wires and this is the thick one.

I think you will find that the wire through terminal B is the connection from the alternator ( terminal 61) to the no charge warning light

There is no terminal C on the alternator ... I think you are looking at the colour code for the wire

 

[SAMYL]

I have had to rewire and fit a new alternator to my son's boat with one of those engines.

I defy anyone to interpret that wiring diagram successfully, especially the connections to the alternator. :nonchalance::disgust::ambivalence:

 

[VicS]

I have had to rewire and fit a new alternator to my son's boat with one of those engines.

I defy anyone to interpret that wiring diagram successfully, especially the connections to the alternator. :nonchalance::disgust::ambivalence:

It's easier if you download a pdf and enlarge it many times

 

[fishermantwo]

A bit puzzled because the diagram you have attached shows only the incoming positive , from the fuse via Teminal C, on terminal 30.

Other green wires are the switched positive supplies to other items on the panel but coming from terminal 75.

I think maybe you have a later panel which has an unswitched supply from terminal 30 to the "extra equipment" switch ( the diagram I am looking at though shows this as a red wire ) but you would not have needed to disconnect it to remove the panel.

Either the wire in question is this latter one, but green) or it is a supply to a switch that is not part of the panel ( hence the need to disconnect it)

Thanks for the replies. The other green wires go to terminal 75 and all the green wire ends have names on them. This wire has 30 on one end and switch on the other. I'm fairly sure it came off by itself as I pulled the panel, there was only about 5 wires I had to disconnect and I sketched a mud map to ensure they went back correct. There are only two switches on the panel, two push pull units at the top. It would have been an easy job if Volvo could have supplied a decent, clear circuit diagram. The diagram is for a Md7a panel, I could not find one for a B.
The end of the wire marked switch has a male spade as well as the female spade if that helps.

 

[VicS]

Thanks for the replies. The other green wires go to terminal 75 and all the green wire ends have names on them. This wire has 30 on one end and switch on the other. I'm fairly sure it came off by itself as I pulled the panel, there was only about 5 wires I had to disconnect and I sketched a mud map to ensure they went back correct. There are only two switches on the panel, two push pull units at the top. It would have been an easy job if Volvo could have supplied a decent, clear circuit diagram. The diagram is for a Md7a panel, I could not find one for a B.
The end of the wire marked switch has a male spade as well as the female spade if that helps.

There is a manual for the MD7B that you can down load from VP's website but its a horrible multilanguage thing . The wiring diagram is the same as the one you have for the MD7A and no clearer. Less useful in fact because there is less labelling and no legend.

This diagram ( from a MD6A manual) clarifies the wiring diagram you posted but also shows dotted the wiring for a tachometer and a connection from 15 to J but that does not connect through to anything

This diagram ( from the same manual) shows an extra wire on terminal 30 , but as a 2.5mm red wire, going to one of the pull switches ( labelled 7 in this diagram) I suspect your mystery wire is this one, but green unless the switch is already wired as in the fist diagram. ( All the labelling is different to the previous diagram )

If not the feed to the pull switch I think I would insulate the wire, leave it disconnected and wait to see what if anything does not work.

I am beginning to see VP wiring diagrams if I close my eyes! Good night for now.

 

[fishermantwo]

Thanks VicS those diagrams are much clearer than what I had. I'm fairly sure it's a stock setup except the starter switch is upside down! Should be able to sort it now. Appreciate all your help

 

[VicS]

Thanks VicS those diagrams are much clearer than what I had. I'm fairly sure it's a stock setup except the starter switch is upside down! Should be able to sort it now. Appreciate all your help

I hope you sort this out too

 

[SAMYL]

It's easier if you download a pdf and enlarge it many times

I totally agree but not practical to do whilst grovelling down in the bilge.

 

[fishermantwo]

I hope you sort this out too

Previous owner was an electrical engineer, that's some of his handiwork. Sitting at the chart table now still fooling around with this. No power at the back of the panel now. Might need a fresh pair of eyes to sort this! Glorious winter day and I would rather be sailing.

 

[Bilgediver]

One regular fault on Volvo installations occurs at the plastic encapsulated fuse. This fuse is usually mounted near the panel and has four elements of which not all may be used. The terminals are often not compatible with the crimps resulting in corrosion and lack of conductivity. I find the easiest way to fault find is with a test light using a 20 watt bulb as then it is easy to find at which point the current stops flowing. Copper filled grease on the spades helps . (Wee tubes in Halfords)

The switches are usually for owner designated equipment and both switches could share a supply either from the key switch run position or utilising one of the fuse elements. If they had been utilised by previous owners then there will be something not working such as compass light or auto pilot .

 

[fishermantwo]

Thanks Bilgediver. I went home and then realized I could have checked the inline fuses, they are just under the bunk I sit on. I'm sure the two switches have never been used. Now that I have a decent diagram I'm confident I have the terminals sorted and once I have power back at the starter switch it will run.

 

[fishermantwo]

Selected the next fuse element this morning and with the wires correctly on the correct pins thanks to VicS's excellent diagram the system works fine. Tossed the green wire into the chart table! Thanks for all the assistance.