New engine install - Instrument panel is dead!

Jokani

Jokani

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I have almost completed the wiring for my replacement MD2020B.

I have 3 wires left:

  1. Alternator field sensing wire
  2. Oil pressure relay
  3. Oil pressure sensor
I ran out of time for the day, but before leaving I could not resist trying to power up the instrument panel, I guess you know where this is going, yep, dead as a dodo!

I quickly tested:

Power to main switch = 13.4v
Power to starter motor = 13.4v
Power to alternator B+ = 13.4v
Unpluggeed and replugged both ends of the instrument panel loom

The intrument panel has a push on/off switch, neither position powers up any of the panel lights, test switch and starter button all dead!

What could be the problem /and/or what should I test next?

MD2020B-wiring-diagram-1.jpg
 
Be useful to see the diagram for after the 16 pole connector. But looking at this diagram it seems likely that terminal 1, fed by the right most fuse could be supplying the panel with power. Check that fuse.
 
PaulRainbow said:
Be useful to see the diagram for after the 16 pole connector. But looking at this diagram it seems likely that terminal 1, fed by the right most fuse could be supplying the panel with power. Check that fuse.
Click to expand...

Hi Paul, I was just about to edit my post, I did also look at the fuse/s, it is a strange configuration, there are 4 fuses in a line, and I think you can use any one of them. 1 was clearly blown, the other 3 looked OK, swapping between the OK looking ones did not make a difference. The fuses do not look replaceable individually, I''l need to see if I can source a complete unit for when/if the need arises.
 
nigelmercier said:
Is your engine the type that has a small "diode loom" inline with the main loom?
Click to expand...

Hi Nigel, to be honest I am unsure if I do or don't, not helped by the fact I'm unsure what a diode loom is. It's my first boat second engine, my previous mechanical experience could be noted on the back of a fag packet (10), I'm slowly building my knowledge, mainly by pushing the boundaries and taking on projects such as this.

I will have a picture of the entire loom on my office PC. I'll look it up tomorrow and post it if that will help diagnose the problem.
 
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GaryCottam said:
Hi Paul, I was just about to edit my post, I did also look at the fuse/s, it is a strange configuration, there are 4 fuses in a line, and I think you can use any one of them. 1 was clearly blown, the other 3 looked OK, swapping between the OK looking ones did not make a difference. The fuses do not look replaceable individually, I''l need to see if I can source a complete unit for when/if the need arises.
Click to expand...
My VP 2002 developed an intermittent fault whereby there was sometimes no power to the starter and instrument panel.
Cured it by replacing the fuse block although it appeared to be fine. After replacing it I did lots of multimeter checks on the old fuse block and it continued to show the intermittent lack of continuity ....very strange.
 
GaryCottam said:
Hi Paul, I was just about to edit my post, I did also look at the fuse/s, it is a strange configuration, there are 4 fuses in a line, and I think you can use any one of them. 1 was clearly blown, the other 3 looked OK, swapping between the OK looking ones did not make a difference. The fuses do not look replaceable individually, I''l need to see if I can source a complete unit for when/if the need arises.
Click to expand...

Just swap to the next fuse. That happened immediately after installing my 2030B. I recall (to my best memory - which ain't great) the panel was dead just because the fuse had blown. The issue was the fuse had blown and courtesy of an electronic wiz friend, he found that in the relay assembly there was a 'thingy'. I can't remember what it is called but it's a cylindrical shaped 'thingy', wire top and bottom about 1.25" long, 3/8th diameter. The body of this was shorting the relay case. Since we were together on cruise, the chum taped up the 'thingy' in insulating tape and let it dangling down. It has dangled down in tape for 21 years ever since without any problem. Sorry I cannot be more precise.
 
GaryCottam said:
Hi Nigel, to be honest I am unsure if I do or don't, not helped by the fact I'm unsure what a diode loom is...
Click to expand...

Follow the link in my signature, go to Downloads. Then open "Volvo Penta 22 Series Instrument Panel & Engine Wiring Diagram DIY Manual", the diode loom is on the page numbered 64. Although shown with a second control panel, I believe this is necessary on all isolated engines with a grounding relay.
 
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I thought volvo engines were "plug and play" The only time I've had starting problems were to do with the relay mounted under the 4 fuse block on the older 2002.
 
Len Ingalls said:
Thia diagram is for the older 2000 series VP. It may be same or similar to your MD 2020

https://www.dropbox.com/s/6mudjj9eplvtgjf/VP 2000 Dash Manual.pdf?dl=0

There is a much better wiring diagram in this VP 2000 manual
Click to expand...

Thanks for the info Len.

reeac said:
My VP 2002 developed an intermittent fault whereby there was sometimes no power to the starter and instrument panel.
Cured it by replacing the fuse block although it appeared to be fine. After replacing it I did lots of multimeter checks on the old fuse block and it continued to show the intermittent lack of continuity ....very strange.
Click to expand...

Thanks for the info, I will order a new unit today.

tillergirl said:
Just swap to the next fuse. That happened immediately after installing my 2030B. I recall (to my best memory - which ain't great) the panel was dead just because the fuse had blown. The issue was the fuse had blown and courtesy of an electronic wiz friend, he found that in the relay assembly there was a 'thingy'. I can't remember what it is called but it's a cylindrical shaped 'thingy', wire top and bottom about 1.25" long, 3/8th diameter. The body of this was shorting the relay case. Since we were together on cruise, the chum taped up the 'thingy' in insulating tape and let it dangling down. It has dangled down in tape for 21 years ever since without any problem. Sorry I cannot be more precise.
Click to expand...

I wonder if that "cylindrical shaped thingy" could have been the diode that Nigle mentions?

nigelmercier said:
Follow the link in my signature, go to Downloads. Then open "Volvo Penta 22 Series Instrument Panel & Engine Wiring Diagram DIY Manual", the diode loom is on the page numbered 64. Although shown with a second control panel, I believe this is necessary on all isolated engines with a grounding relay.
Click to expand...

Thanks for the link/info Nigel

I haven't seen anything that looks like a diode at the instrument panel end, at the engine end of the loom most of the wiring is covered in black tubing, would I be best to remove the tubing to see if I can find a diode.

Would the diode I am looking for be part 17 on this schematic?:

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7746410-30-1963.aspx

Below are some pics of the loom taken before fitting:

diode-1.jpg


diode-2.jpg


diode-4.jpg
 
Get your multimeter out again Gary. Check for positive 12v :

Into the fuse block.
The wire going out of the fuse block.
Same wire out of the 16 pin connector (if poss).
Same wire when it gets to the panel.

A better diagram would help.
 
PaulRainbow said:
A better diagram would help.
Click to expand...

The multimeter will be out on Thursday, unfortunately no time off until then.

This is the diagram (supplied by Len) which is a bit better, it is for a VP2003, the battery/switch/starter connection is different, but the connections to the control panel appear to be the same as for the MD2020B:

better-wiring-diagram-vp2003-diffferent-earth.jpg
 
As per my posts #2 and #12, start from the fuse and work up to the switch (4) in the diagram. If (4) is live check the starter button, if that's live the starter should engage if you press the button.
 
GaryCottam said:
Thanks for the info Len.





Thanks for the info, I will order a new unit today.



I wonder if that "cylindrical shaped thingy" could have been the diode that Nigle mentions?



Thanks for the link/info Nigel

I haven't seen anything that looks like a diode at the instrument panel end, at the engine end of the loom most of the wiring is covered in black tubing, would I be best to remove the tubing to see if I can find a diode.

Would the diode I am looking for be part 17 on this schematic?:

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7746410-30-1963.aspx

Below are some pics of the loom taken before fitting:

diode-1.jpg


diode-2.jpg


diode-4.jpg
Click to expand...

YW
In the lowest photo,there is a BL/R? wire coming out of loom & twisted? together with another BL/ ?R? wire going into connector box. Looks like a "ratty" splice. BL/R is the power wire colour in diag. & is conn. to the R wire of fuse block at term 1 of loom connector. This would be the 12V supply wire to dash I believe.
Just guessing-but in any case that splice looks like it needs some work.
Len
 
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Len Ingalls said:
YW
In the lowest photo,there is a BL/R? wire coming out of loom & twisted? together with another BL/ ?R? wire going into connector box. Looks like a "ratty" splice. BL/R is the power wire colour in diag. & is conn. to the R wire of fuse block at term 1 of loom connector. This would be the 12V supply wire to dash I believe.
Just guessing-but in any case that splice looks like it needs some work.
Len
Click to expand...

Well spotted Len, I had previusly posted a question re that splice here

I did cut it out and re-join it.

Hopefully that is not the source of my current problems.

I have the day off on Thursday, hopefully I will find out then.
 
GaryCottam said:
Well spotted Len, I had previusly posted a question re that splice here

I did cut it out and re-join it.

Hopefully that is not the source of my current problems.

I have the day off on Thursday, hopefully I will find out then.
Click to expand...

That may be where the 33ohm resistor went-inline with the two Bl/R wires.
The resistor is shown as #9 in the diagram in old post linked above.
The old post suggested the resistor was there to "make up" for the use of LED instead of the old incandescent BAT(Charge) warning lamp in your dash panel.
I don't know if this applies to your situation or not-but it's worth looking into. If you do need a 33ohm resistor,the diagram specs a 9watt-(or larger wattage) available at any electronic part supplier.
 
Last edited:
GaryCottam said:
The multimeter will be out on Thursday, unfortunately no time off until then.

This is the diagram (supplied by Len) which is a bit better, it is for a VP2003, the battery/switch/starter connection is different, but the connections to the control panel appear to be the same as for the MD2020B:

]
Click to expand...

GaryCottam said:
Well spotted Len, I had previusly posted a question re that splice here

I did cut it out and re-join it.

Hopefully that is not the source of my current problems.

I have the day off on Thursday, hopefully I will find out then.
Click to expand...

For goodness sake You are wiring a MD2020B , not a VP 2003
You have already posted the correct wiring diagram in #1 Refer to that diagram !

The BL/R wire is the excitation supply to the alternator.. A break in it may affect the operation of the alternator but is not related to your lack of power to the panel

The main power feed to the panel is the heavier ( 2.5mm²) RED wire via the fuse block and pin 1 of the multipin connector.

Pressing the power On/Off button on the panel should energise the panel and the blue/red wire.
( I wonder if the ratty splice existed because someone has removed the excitation resistance #9. ???)

Do not test for power with a digital multimeter. They draw such a low current that they will give a normal reading through bad connections and make a fool of you. Use a test lamp, or a lamp in parallel with the meter instead.

This is the wiring diagram of the keyless control panel

VP%20keyless%20panel.jpg
 
Len Ingalls said:
YW
In the lowest photo,there is a BL/R? wire coming out of loom & twisted? together with another BL/ ?R? wire going into connector box. Looks like a "ratty" splice. BL/R is the power wire colour in diag. & is conn. to the R wire of fuse block at term 1 of loom connector. This would be the 12V supply wire to dash I believe.
Just guessing-but in any case that splice looks like it needs some work.
Len
Click to expand...
Edit: The Bl/R wire is not the +12V feed to term #1.
The Bl/R wire is the source of field excitation from the dash BAT(Charge) lamp (+12V) to the alternator field term #61 & MAY have a 33ohm/9Watt resistor in series with it-as pointed out by Vic in previous thread. Sorry./ Len
 
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