help please 1992 Hymer 544 Lighting Wiring Fault Forums

thegreatpan

Help,

The following bank of lights on my 1992 Hymer 544 MH are all fed from the same fuse; cab lights, above cab bed light and and the bench seat fluorescent. None of these have worked since I bought the van.

Today I have spent the day with multimeter and found out that all fuses are ok, I am getting 12.4 volts on the blue wire that feeds all these fittings(according to the wiring diagram). But worryingly I am also getting 11.6 volts on what should be the earth?

Please can someone tell me how I can get the earth to read voltage without blowing the fuse?

The Truma boiler etc works from the same fuse and is fine as it has a different earth path.

I removed the fluorescent and wired it to a spare battery and it works fine, I also did this with all the festoon bulbs from the cab lights and they are fine.

Any one tell me where to start

dava

Hi

It puzzles me on how you measured 11.6v to earth. Which earth did you use? ie did you measure from one earth to another and as you would hope you should get 0V.

If you got 11.6v from earth to earth then yes some thing wrong.

If you connect these two earths together via a fuse and it blows then you have a partial short somewhere along the line.

I would disconnect the earth to the lights and connect another earth from somewhere else and see if that works.

David

sallytrafic · Southern Rally Co-ordinator

Those are the classic symptoms of an earth fault. Wire isn't completely off otherwise you would have measured the same voltage both sides of your light fitting (a dvm draws so little current that there is no voltage drop across the device).

thegreatpan

All voltages were read with the multimeter being earthed to the chassis via the clutch pedal?

Has me perplexed, I can only assume the earth has become insulated/broken from its normal return path to the battery negative and is picking up a live feed?

The wires run through the pull down bed,that is next on my list to check.

Any ideas anyone?

sallytrafic · Southern Rally Co-ordinator

JohnsCrossMotorHomes

Hi,

If you can't get it sorted and as your in East Sussex, bring it in to us and we will have a look and see if we can sort it.

But as Gerald says it look like you have not got an decent earth, try putting a wire lead the other side of the lamp and earth it to the chassis somewhere.

Regards and good luck.

Peter

sallytrafic · Southern Rally Co-ordinator

thegreatpan

Dear All,

Thanks for the suggestions so far,

Frank(Gerald?) any more diagrams to help a numpty like me would be much appreciated.

Due to stropy neighbours and restrictive covenants, I have had to put the MH back into storage, as I am away on work this week,

I am coming up to my duty weekends with days off mid-week where I will have another go with the mutimeter. I aim to trace all the wiring and label them, as the leisure battery area is a bit like spaghetti, due to all the extras that were fitted to the van by the previous owner.

What was bewildering was that all of the various light fittings that shared the common earth showed the same voltage on the earth wire, whether they were connected to the fitting, or removed and a reading was taken from the naked unconnected spade connector (using the chassis earth). Hence my reasoning for the system getting a feed on the earth side.

What would happen if I were to create a new earth for these lights?