Truma Trumatic C 3402 Blow Heater Issue

[settloe_99]

Hello,

I've developed an issue with my Trumatic c3402 blow heater. The boiler works fine for hot water, but the blow heater has stopped working (or works very intermittently). When I took the cupboard apart to get to the boiler, I found that someone had previously disconnected the black wire in this picture. I can't see where this cable runs to, but when I reconnected it, the blow heater started up, but the main power switch to the 12v system was in the off position. I've never disconnected the cable, so clearly, a previous owner has for some reason and until recently, the heater worked with it disconnected.

My only theory is that the heater was stuck on at some point, and someone disconnected it to stop it, but if that is the case, how did it work for the two years I've owned the van until now?

I've searched online and found a few articles suggesting that a faulty PCB could be the issue, but I'm reluctant to remove the PCB as I'd probably need to remove the whole boiler to get it out.

Any suggestions would be greatly appreciated!

Thanks

Matt

 

[Mr Plodd]

That white "chocolate block" connector certainly isn't standard original fit, so I think you are right, someone has "tinkered" in the past. But that doesn't answer your question of course.

The black cable is pretty thick so is designed to carry a reasonable 12v load. But of course there is no way of knowing if its original, or a bit someone had "lying around" and they used for an application that didn't actually need such substantial cable?

Looking at the picture my interpretation is that the white and red at the "top" are the positive feed (red) and earth (white) The two blues coming out of the bottom are earth cable for 2 separate 12v items and the red and black cables positive supplies for two items. Tge fact that one is black and nit red reads to make me think that it's for something that has been added by an owner who wasn't bothered about colour coding the wire. But what that is is anyone's guess!
Time for a bit of wire tracing methinks

 

[ProfJohnL]

Trying to second guess bodged wiring without being there to do the tracing and checks is fraught with unknowns.

 

[settloe_99]

That white "chocolate block" connector certainly isn't standard original fit, so I think you are right, someone has "tinkered" in the past. But that doesn't answer your question of course.

The black cable is pretty thick so is designed to carry a reasonable 12v load. But of course there is no way of knowing if its original, or a bit someone had "lying around" and they used for an application that didn't actually need such substantial cable?

Looking at the picture my interpretation is that the white and red at the "top" are the positive feed (red) and earth (white) The two blues coming out of the bottom are earth cable for 2 separate 12v items and the red and black cables positive supplies for two items. Tge fact that one is black and nit red reads to make me think that it's for something that has been added by an owner who wasn't bothered about colour coding the wire. But what that is is anyone's guess!
Time for a bit of wire tracing methinks

Thanks, Mr Plodd.

I think the black cable is original, as I've traced it back as far as possible, and it seems to run into the wall or floor near the heating control panel. The blue wire has also been messed with at some point as when I traced it back, it runs to the negative terminal on the battery but changes to a brown wire, and someone had badly joined the two cables together, so initially, I thought it was this bad joint which was causing the issue, but I've since joined them properly and soldered the joint and tested that wire and it is fine now.

 

[settloe_99]

Trying to second guess bodged wiring without being there to do the tracing and checks is fraught with unknowns.

Agreed. I suppose I really need to know how it should be wired up correctly, and then I could start again and re-wire it correctly.

 

[Dustydog]

Look on line or in your own caravan handbook and papers . Locate the correct wiring diagram for your model and follow all the cables. Be very careful not to cross wire. That alone could blow something like the pcb costing a fortune.Bodged wiring is always a concern, you wonder why?