Truma CP Plus panel problem

cyberyacht
cyberyacht Forum Participant Posts: 10,218
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edited October 2021 in Motorhomes #1

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.

Comments

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited October 2021 #2

    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.

     

  • DavidKlyne
    DavidKlyne Club Member Posts: 13,857 ✭✭✭
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    edited October 2021 #3

    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?

  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited October 2021 #4

    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.

  • young thomas
    young thomas Forum Participant Posts: 11,356
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    edited October 2021 #5

    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.

  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited October 2021 #6

    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.

  • young thomas
    young thomas Forum Participant Posts: 11,356
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    edited October 2021 #7

    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.

  • young thomas
    young thomas Forum Participant Posts: 11,356
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    edited October 2021 #8

    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.

  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited October 2021 #9

    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.

  • Unknown
    Unknown Forum Participant
    edited October 2021 #10
    The user and all related content has been Deleted User
  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited October 2021 #11

    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.

  • Unknown
    Unknown Forum Participant
    edited October 2021 #12
    The user and all related content has been Deleted User
  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited October 2021 #13

    I had. However in recent developments it was discovered that the negative feed had inadvertently been connected to the hab battery + terminal. Equilibrium has been restored. If anyone has a hair shirt, size 15 collar.....embarassed

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited October 2021 #14

    Ooops! 🙄