The question is whether they could potentially be the issue preventing all the lights from working. I could, for example, swap them to see if that helps, but I am not sure if this would make any difference.
The relays look in good condition, the contacts aren't damaged and there no evidence of arcing ( metallic black/grey deposit on plastic case) also the coils have no discolouration which would indicate overheating ( which would cause the wire in the coil to break).The bottom relay is probably the isolate relay ( cuts off the 12V system when the car is plugged in).So if the rest of the 12V systems are working( orange wires have +12V on them) then that relay contacts are OK.
Tracing out the green (with brown markers) wires is the next thing to check, do they have +12V on the them . A convenient 0V in the fuse box is the black wire on the bottom relay.
Tracing out the green (with brown markers) wires is the next thing to check, do they have +12V on the them . A convenient 0V in the fuse box is the black wire on the bottom relay.
Thank you. I will check it out later today. I have a wire extension for my multimeter, so I will make sure to check whether it is the ground or the V+ that is discontinuous.
Another update after a full afternoon of testing.
When I connect my multimeter’s negative probe to a separate known good earth (chassis or battery negative), I’m getting +12 V on both terminals of the bulb connector. That means the positive feed is fine, but the negative/earth return isn’t actually connected — it’s floating at the same potential as the live side.
So the fault definitely appears to be on the earth side of the lighting circuit rather than the power feed.
When I connect my multimeter’s negative probe to a separate known good earth (chassis or battery negative), I’m getting +12 V on both terminals of the bulb connector. That means the positive feed is fine, but the negative/earth return isn’t actually connected — it’s floating at the same potential as the live side.
So the fault definitely appears to be on the earth side of the lighting circuit rather than the power feed.
What make if known is the unit,on my system the negative cables are collectively fitted into a 12 way plug that is inturn is connected to a 12 way socket fixed on the unit,if this was to become loose on mine for whatever reason I would lose all V- ,perhaps if only partially loose it may only be certain circuit(s) that were lost
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You have identified your fault! Now you have to try and work out where the physical location of the fault is or to try a work round such as providing a new 0V connection wire to the common 0V point. You must not rely on the chassis or other metallic parts of the caravan to carry 0V currents. or mains earth connections.
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