Error 10 Thermoking Spectrum SL 2 50

Hi,

We have just purchased a used semi trailer with Thermo King SL 250 refrigeration unit.

It works just fine on the engine, but when we select the 3 phase land line it gives error code 10. This is listed as Discharge Pressure High, but as it works ok on engine I'm thinking it may have another meaning. I have tried the reset button a number of times and checked for correct voltage in from the landline.

Any ideas!!

Thanks

Which host unit is fitted to the SL evaporator? This info is needed if you want help with host unit problems.

They have two HP switches one for road and one forvstandby check wiring to both switch's which are fitted to the compressor manifold ,disconnect both because ivdo not know which is which, and check if ones open circuit also check all fuses in control panel

Where in the UK are you located?