Swedish beauty not lighting up

[luke73]

Hello, any auto electricians out there?
I have been having a problem with my 1988 (swedish) caravan rear main lights. The indicators and brake lights work fine but the main lights do not. They have come on intermittently as i tried to fit new bulbs. I tested the car 7 pin plug and the two main light contacts showed 11-14v, after connecting to the caravan only one was still at 11-14v, the other was 1-4v ( it went from 1 to 2 to 3 to 4 v and then no further). Now neither of the car 7 pin plug mains have any power but the other lights on the caravan are still working.
Any ideas would be gratefully received as we are supposed to be heading off on a road trip in 2 weeks and have to get it through its Swedish MOT before hand!
Thank you

 

[ProfJohnL]

Are you sure you have the correct replacement bulbs? and that you have inserted then in teh correct orientation. - I remember once having a problem with a dual filament bulb where it had antisymmetric bayonet fixing, but becasue of the sloppiness of the bulb holder I managed to fit it the wrong way round and got some strange results.

Most road lighting problems on UK caravans are found to be corroded contacts on bulb holders and on the electrical wire connections to them.

Similar problems can arise in the multipin connector to the car, again cleaning contacts and making sure none are deformed.

These are good places to start.

 

[Thingy]

Have you checked the fuses? Not sure about your caravan but you should have a seperate 12v fuse board, seperate to your consumer electrics that is.

 

[Hutch]

Thingy, not normal fuse's in Caravans for running lights, it sound more likely to be earthing links from the light units. As the Prof has suggested. A pain but go through them all. Indicator and rear light and fog etc. For earthing connectors.

 

[Thingy]

Just re read the OP post. Sounds like the issue may be on the car, not the caravan, possibly a short to earth. Just thinking, you havent changed your car by any chance. Is this a combination that has worked in the past?

Hutch, my caravan has a seperate fusebox inc fuses for road lights, located where i was suggesting.

On the board:

fuse 2 LH tail lights
fuse 3 RH indicators
fuse 4 Fog Lights
fuse 7 RH tail lights
fuse 8 LH Indicators
fuse 9 Stop Lights
fuse 10 Reverse Lights

all 5amp except for 7.5 amp at fuse 9.

May be wrong but I thought all caravans had a 12v fuse board. I had to plug a VLM4 module from Sargent into this to compensate for the LEDs.

Some tow vehicle electrical systems may not be fully compatible with the LED road lights fitted to modern trailers and caravans, including the new range from Swift. In cases where problems are identified, an electronic control unit (VLM4) can be ordered direct from Sargent Electrical Services Limited for installation in the caravan. This unit simply plugs in-line with the 13 pin car connection cable at the rear of the caravan towing fuse box.

 

[luke73]

Are you sure you have the correct replacement bulbs? and that you have inserted then in teh correct orientation. - I remember once having a problem with a dual filament bulb where it had antisymmetric bayonet fixing, but becasue of the sloppiness of the bulb holder I managed to fit it the wrong way round and got some strange results.

Most road lighting problems on UK caravans are found to be corroded contacts on bulb holders and on the electrical wire connections to them.

Similar problems can arise in the multipin connector to the car, again cleaning contacts and making sure none are deformed.

These are good places to start.

Thanks for your fast reply, i did originally put the incorrect replacement bulb in, but then noticed it was a single contact not dual. I have used some sandpaper to clean the contacts but not sure how good they are still, i will have another go. I replaced the multi pin on car and caravan, and have since double checked the connections. I will do the contacts again though. cheers

 

[luke73]

It has done a similar thing on both my cars. First my 2018 renault trafic, rear left worked fine but right was only side light, then stopped altogether. Then both rear mains went out and no voltage on the car side of the plug (going to main rears, grey and green on mine). So i tested the car side on my 2009 kia and both had voltage to rears, connected to caravan , lights came on momentarily then went out . re-tested car side and no voltage on one and alternating voltage between 1-4 v on the other!!

 

[Thingy]

So, if its doing it on both vehicles, it seems you have narrowed it down at least to the caravan. It does seem strange that you have an almost identical fluctuating voltage, but both caravan and car are too old for what first occured to me. I think you need to be following Profs first advice and also check the whole wiring loom for damage.

 

[luke73]

clean and check time then. thank you