12v Fridge supply.

[Pike]

I have a problem with my Thetford fridge not working on the 12v supply when the engine is running. ( error code 6 )

I have checked all of the fuses and note that on the EM40 Interface box the 20 amp fuse marked fridge D+ 12v appears when the engine is switched on. The 20amp fuse marked fridge has no voltage weather the engine is on or off. My Motorhome is an Auto trail tracker FB 2016.

 

[daveclare]

Although not an Autotrail mine had the same symptoms. The fault was the 50 amp fuse from the main battery (not hab) had blown. This was located under the floor by passenger seat right next to battery.

 

[The Old Man]

With my Adria I had a similar issue.

The wire from the engine to the Electrobox had failed, so no signal that the engine was running was being received.

 

[GeoffnDee]

It May be worth checking the multi-plugs that I think are on the rear of the EM40 are ok also is there another fridge fuse on the PSU ?

 

[Pike]

Thanks for all your suggestions, I have looked into all of them but no luck yet.

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[GeoffnDee]

I wonder if the 12v heater element could have gone open circuit as I think this would then show 0v across the main 20amp Fridge fuse with the engine running or not ( Is your Thetford Fridge a N3000 series ? )

 

[Pike]

Yes it's a N3000 series.

 

[autorouter]

On the EM40 interface, there is a 4-way connector (red, I think) for the power input from the vehicle starter battery. Two terminals for positive, two for negative. They should be permanently on, ie about 12V all the time. If not, there's a problem with the mains starter battery fuse or the wiring from the starter battery to the EM40.

If that's OK, there should be 12V at one of the terminals of the 'Fridge' fuse slot. (and nothing at the other fuse slot terminal). If not, there's a fault with the EM40 internal wiring. If OK, then inserting a good fuse into that slot should result in 12V at the 'Fridge Perm' terminals (two of the terminals on the green 4-way connector. This should also be on constantly

The other 2 terminals of the green 4-way are the D+ (engine running) signal, which is 12V when the engine is running,and zero when not running.

 

[Pike]

Thanks for this, much appreciated .

 

[iain26]

Please check the connectors on the back of the EM40 board as they are renowned for overheating and burning. In particular the red one, the black one and the green one which carries the current from the battery to the dc fridge heater.
You may still see correct voltage on these terminals but when the load is applied they cannot pass the current.

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[Pike]

Thanks to everyone. I have checked the 12v going in and both OK, but no 12v coming out of the EM 40. So will need to order a new one from Sargent. Thanks again for all your help.