Thetford N145 no longer working on 12V (1 Viewer)

[Evildoody]

Things just go from bad to worse, a dealer I went to today had a practically brand new "working" Thetford N3150 that a customer did not want as it was too small and offered to sell it to me for the bargain price of £450. I snapped up the offer. Anyway I managed to get the N145 replaced with the N3150 after struggling to get it through the garage door (habitation door too small), got it all wired up with a big grin on my face and Bam, the bloody thing won't work on 12V. Comes up with error code 4. I followed Thetfords troubleshooting guide to check that the voltage to the fridge is a steady voltage between 9.5V and 15V and that the D+ voltage is in the same range and yes, they both are 13.5V with the engine running, 13V for the high current + and - with the engine off and 0V at D+. Now I am either the unluckiest person on the planet and the new fridge also has a control board issue, or I am missing something (braincells perhaps!).

I have wired the orange cable to D+ and I have attached the low current purple to the + of the high current supply and the low current - black to the negative of the high current supply (there was no other supply at the back of the fridge). the purple and black wires are for the electronics - so I am sure this should be ok?

Can anyone advise before I torch my van - lol

Installation guide for the N3150 :-

https://www.thetford.com/wp-content/uploads/2015/04/N3104-N3150-Installation-and-Owners-Manual.pdf

 

[Evildoody]

I spoke to the dealer, he said "check the 12VDC connections, in case I have the DC element connected wrong"

He had all the connections to the power board disconnected and connected them all in preparation for me collecting the fridge, and may have inadvertently reversed the polarity (I will check connections tomorrow). I have had a little while to think about this, and in my opinion it can only be an issue at the fridge, and by that can only be an incorrect wiring to the power module or the power module being faulty, but I am assured the fridge was working so that leaves the former.

If someone can provide a pic of an N3150 board in situ, that would be great (long-shot).
Looking at the Thetford manual, it would suggest from left to right +, -, +, - (referring to DC and AC elements)

NB. It cannot be a voltage issue to the fridge (as the voltage is fine), therefore I am indeed the unluckiest b******d in the world.
I ascertain that the N145 has a power board problem and the N3150 has a "dealer" wiring mishap (or a power board issue). Anyway, tomorrow it will either be a working N3150 or two fridges with power board issues.

PS - I have a great Avatar - lol

 

[Evildoody]

Sorted, the positive of the DC heater cable on the N3150 power board was not connected properly. I have sent the power board from the N145 off for repair, so I should have a working N145 for sale soon.

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