Truma CP Plus panel problem

Truma equipment works in mysterious ways, but I’ve always found Rachel at Truma Technical UK (contact via website) very good and she’ll refer to the guys in Germany if she can’t sort it herself.

 

I tend to switch the CP panel off by pressing the round button until OFF shows on the screen. Perhaps a silly suggestion but do you need to manually switch the button on if there has been a power interruption? I think the CP panel is still live even if the 12v switch is off?

It's the lack of current when I turn the power from OFF to ON that puzzles me. I've tried all manner of button presses from short to long.

CY, along with the suggestion in my email, you could try and pull the two fuses on the Truma unit and check them...I know this will be a pain due to its location but if you can pull open the front cover by the bed steps you can get access....

yes, the confusing bit is why no power when isolator is ON, but power when isolator OFF! Seriously odd.

I currently have the panel/steps off. As you say, a bit of a pain. Accessing the fuses on the Truma unit is still tricky and, as of last night I had still not managed to prise the cover off. Why on earth would anyone make something like a fuse so inaccessible?  I did read elsewhere a reference to a 1A fuse adjacent to the actual display panel but haven't found one and I've no idea where the wires go to.

I'm reluctant to shell out around £150 for a new Truma panel if that isn't the problem.

A bit old but might at least get the panel going....not sure which fuse is 'no 12', might be a reference to something in the OP's Roller Team van.

https://www.caravantalk.co.uk/community/topic/95848-truma-c-p-plus-heating-control-panel/

the cover on the Truma is a sort of slide-off affair, rather than pull...

presume all was working prior to battery change? Possible surge blew fuse when changing it?

still very odd that current present when Isolator OFF but not there when ON.

I Checked mine yesterday and the Truma was ON with the over door master control panel completely OFF, so there is a permanent feed...although I haven't checked if this disappears when the Isolator is OFF...as I have only used this once.

I seem to recall the Truma did go OFF and then back ON when isolator turned back on.

time for local mobile Truma guy?....

good luck.

CY, a thought....

when you describe the panel as 'blank' is it completely blank or does it have the black line on it or not...

if it does, then this is a different problem...I think.

many comment re low voltage but you have tried on EHU haven't you....could the battery be low?

other comments re removing round control knob (pull) to reveal a screw that can remove panel...unplug and replug to reset....

If black line present, I'm favouring low battery but that still seems odd...

if black line not present then probably a fuse or reset...

getting beyond me a bit now....sorry.

I have the black line. It is currently sat on my desk and even after 15-20 minutes with no connections at all, it still has the black line. I'm wondering whether to disconnect the ribbon feed to the display to see if that changes anything, although I suspect not.

The real puzzle is the loss of 12v when the isolator goes from OFF to ON. One would expect it to be the other way round. Something, somewhere seems to be cutting off the supply when all the rest of the van circuitry goes live.

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Yes, I have a fused isolator switch which makes it easy to cut the solar circuits. Solar side of things is still fine.

It's the loss of 12v to the display panel when the main isolator switch is turned to ON to make all the other van 12v stuff live that is the puzzle. I've confirmed that the 2A fuse referred to in the Carthago handbook is good.