12v supply to fridge fault after testing voltage !! Help please

[Joggerdude]

The 12v whilst driving, has not been keeping the fridge cool on journeys for some time now.
I therefore decided to check the fridge voltage etc.
Resistance for the heater was ok at 1.4 ohms.
The output from the car was fine at 13.8v, so I tried to check the voltage to the heating element by tapping into the 2 brown wires leading to the element with probes and a multimeter.
After I made these connections, I switched on the fridge to 12v (car running). Immediately the 12v fridge light stated flashing in time to a clicking noise (1 second intervals) from the interior of the van.
This just keeps going until I move from 12v. I disconnected the probes and mulitmeter from the heater supply leads, but the flashing and clicking still occurs when 12v is again selected.
Seems like I have screwed something up by making the multimeter connection to those leads?
Mains and GAS works ok.
Any advice on how to fix would be very welcome.

NOTE. Fridge is Dometic RM7291 circa 2005 which has manual selected power source.

 

[gary]

You should have.connected between one brown wire and earth, both browns are positive forming a loop in and out of the element coil

 

[Joggerdude]

Ok, I get that. Thanks
So what fault could I have caused, and how do I rectify the problem?

 

[Dustydog]

Does increasing the cars rpm from idle to say 1500rpm make any difference?
Have you identified the locus of the clicking?
What make model of caravan?
Do you have a Nordelectronica unit?
Have you checked the fridge 12 v output from the cars socket 12s or 13 pin?

 

[Sam Vimes]

Do you have a car with a Smart Alternator? Mine has and will not keep the fridge permanently alive as the alternator voltage is not constant.

Some fridges monitor the 12v supply and if too low will turn off and issue a warning. This is the case when my Smart Alternator is in the low state and the car runs from it's battery. Then the car electronics decide the car battery needs charging and the alternator voltage is raised. On the raised state the voltage at the 13pin connector can be about over 13v but in the low state, below 12v. Voltage drops on the caravan wiring make the voltage at the fridge even lower.

In my case it also discharges the caravan battery to the point where it permanently killed it.

If this is your problem there are fixes but not cheap.

 

[Ferrodo]

I had that a few years ago. Turned out to be a voltage drop due to a cheap voltage sensing relay. I replaced it with a heavy duty beast and that cured it.