Truma CP Plus panel blank

[cyberyacht]

Habitation Isolator switch has been off since last trip away. Fitted a new battery. Solar display shows normal output. Isolator switch to ON. All 12v electrics appear OK. Truma panel normally lights up when Isolator switched ON. Completely blank. Panel off, remove data cable, check power supply = 0. Turn Isolator OFF, power supply then reads 12.9v. Panel still blank. Connect van to mains and repeat earlier checks - same result. Reluctant to shell out £150 for new panel if that isn't the problem. Complex electrics are not really my forte so any guidance would be welcome. If I am able to resolve this, I don't want a repeat when I link up the second battery in a week or so when the voltages and charge levels are equalised, although I can't see why swapping a battery in the van should have affected it.

 

[Lenny HB]

Have you Checked the panels fuse?
Normally a 20mm glass fuse in a holder mounted behind the panel.

 

[cyberyacht]

Couldn't see a fuse holder when meter removed. Didn't go looking for one as 12.9v present. Still puzzled that the supply cuts off when main isolator switch is turned on. Weird. Any ideas?

 

[Pausim]

I think the panel gets it’s power from the data link to the boiler. Is it possible that a fuse has failed in the heater or it’s supply?

 

[jezport]

I think the panel gets it’s power from the data link to the boiler. Is it possible that a fuse has failed in the heater or it’s supply?

12v is directly to the board not on data cable

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[Ditcha]

I know on our Malibu there is a separate 1amp fuse for the CP unit which is a separate blade fuse in amongst the wiring behind the panel, ours is schaudt not cbe which I think yours is.
If I remember correctly with the cbe setup the fuse is in with some more fuses separately from the main fuses in a small white box
at the rear with all the other electrical equipment worth a check.

 

[cyberyacht]

Not been able to locate any supplementary fuse boxes. The absence of any sort of wiring diagram for all this kit doesn't help.

 

[Ditcha]

If it is CBE unit it should look something like this

 

[Pausim]

On my Compactline there are also some fuses under the floor by the habitation door. They are next to the isolation switch.

 

[cyberyacht]

I've now checked all those. I did find a blown 20A one in the small box (blue arrow) although what it controlled, I've no idea as I hadn't found anything else not working. The Truma panel is still blank so that would seem to have raised my hopes prematurely. Having dismembered the interior, I still can't get my hand in to anything on the actual boiler although with the aid of a dental mirror I can see what I think is a fuse. Just to confirm, is it a multi coloured thing about 15mm long in a pair of 'terry clips'?

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[Pausim]

I think the multi coloured one may be the 10A 240V mains one. The 12V one is higher up the panel and usually more accessible than the mains one. When my mains one blew it didn’t affect the panel beyond showing a fault code. I have never had the 12V one blow so have no idea how it might affect the panel.
This is where the 12V fuse is.

This is where the mains fuse is.

 

[Ditcha]

On my Compactline there are also some fuses under the floor by the habitation door. They are next to the isolation switch.

Have you checked these fuses? Under the floor

 

[cyberyacht]

As stated above, checked them all except the ones on the actual boiler which I can't reach.

 

[Pausim]

On my Compactline there are vents from the boiler compartment into the under bed wardrobe. These vents pull out and may make access to the boiler easier.

 

[cyberyacht]

My vents are on the panel facing into the van by the bed step. The side of the boiler with the fuses/wiring faces the garage wall where the electricity box is mounted.

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[Pausim]

My vents are on the panel facing into the van by the bed step. The side of the boiler with the fuses/wiring faces the garage wall where the electricity box is mounted.

Different arrangement, shame. What model is your compactline?

 

[cyberyacht]

2016 - 138

 

[charliesgrandad]

Have you tried taking a separate temporary 12v supply to the CP panel ?

 

[Vansflyer]

Not sure this is any good for you but worth a punt, manual from a 2018 model. On our C-Tourer the Truma fuse is separate to all the others and behind the white box with the fuses in, no ides what not "in the box" with all the rest. Worth a dig around to see and loose fuses, good luck.

 

[cyberyacht]

The fuse (2A) on mine is situated in the subfloor at the forward end of the battery compartment. I've confirmed that this feeds the panel. What I have to work out is why that supply is cut off when the main isolator switch is turned to ON.

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[Pausim]

Sometimes fuses look ok but are not. Have you tried changing the 2A fuse?

 

[cyberyacht]

I had checked the integrity of the fuse. However, after working systematically through everything again I have to confess that I had inadvertently connected the negative feed from the panel to the positive terminal on the battery so it's hair shirt time. Thanks for people's input and sorry to have wasted your time.

 

[Pausim]

I had checked the integrity of the fuse. However, after working systematically through everything again I have to confess that I had inadvertently connected the negative feed from the panel to the positive terminal on the battery so it's hair shirt time. Thanks for people's input and sorry to have wasted your time.

Glad to hear you have traced the problem. Not a waste of time there was useful information in the discussion.