I connected up my 'van (2004 Dethleffs 550L) to the towcar (2008 Volvo V70) yesterday to test the running lights. Everything looked fine but, about 45 seconds after connecting, all the RH / offside "side" lights went off. The indicators work fine and, if I turn everything off, disconnect and then reconnect, the side lights work again but then go off again. I have a small trailer and its lights work fine (i.e. stay lit). Any ideas where to start looking? I have a multimeter. The towcar is fitted with 12N and 12S sockets.
Running lights faulty
- Thread starter johnfryett
- Start date
Hello John,
That's a strange one, but my first thought is a poor connections in one or more light fittings. My guess is that whilst every thing is cold all the metal parts has contracted and tighten down all the connections, but when the lights are on, the heat from the bulbs, warm up the fittings, and allow poor connections to start playing up.
I suggest you open all the light fittings, ( even the ones that appear to be working) tighten up all connections. Perhaps a light spray of WD 40 or similar water dispersal to help keep things working well. Keep the spray away from the reflectors, bulbs and lenses.
That's a strange one, but my first thought is a poor connections in one or more light fittings. My guess is that whilst every thing is cold all the metal parts has contracted and tighten down all the connections, but when the lights are on, the heat from the bulbs, warm up the fittings, and allow poor connections to start playing up.
I suggest you open all the light fittings, ( even the ones that appear to be working) tighten up all connections. Perhaps a light spray of WD 40 or similar water dispersal to help keep things working well. Keep the spray away from the reflectors, bulbs and lenses.
The pins in the 12S plug and socket tend to close up and corrode with use.
In addition to the Prof's advice try gently opening the pins with a small screw driver. Spray both plug and socket with electrical contact spray which cleans the contact surfaces.
In addition to the Prof's advice try gently opening the pins with a small screw driver. Spray both plug and socket with electrical contact spray which cleans the contact surfaces.
hi, as the other trailer works fine, it must be the caravan wiring, "yes" !!, does the front marker light go out at the same time, !! if it does then it is likely to be the plug, as this feeds both lights on the right side down the "brown wire" check the plug first for a poor connection or broken feed wire. if the front marker light stay on it is likely to be the rear light cluster.
dismantle it and check this out as the Prof said.
dismantle it and check this out as the Prof said.
Since your trailer lights work and stay on, this suggests the supply at the car is good. Therefore check the caravan 7 pin socket, for loose connection. Also the right side earth point for corrosion. This may be on the right or left side, probably at one of the rear light units.
If these don't reveal the problem, check the road lighting caravan fuse by replacing it. Occasionally a fuse may look ok and work ok till it gets warm
If these don't reveal the problem, check the road lighting caravan fuse by replacing it. Occasionally a fuse may look ok and work ok till it gets warm
Thanks for the suggestions. I've located the CANBUS unit in the car and tested with the multimeter as follows:
1. Ignition on, lights on, both sides road lights on, good voltage across LH and RH road light terminals
2. Wait for about a minute, RH road lights go off, now little or no voltage across RH road light terminals.
So this suggests that the CANBUS unit might be faulty - am I right? Or it could be reacting to a fault in the caravan wiring...
However, I've also dismantled the 12N plug and tested the wiring inside. Using the circuit detection setting on the multimeter, I get a circuit between any two of the "positive" leads - that seems wrong.
1. Ignition on, lights on, both sides road lights on, good voltage across LH and RH road light terminals
2. Wait for about a minute, RH road lights go off, now little or no voltage across RH road light terminals.
So this suggests that the CANBUS unit might be faulty - am I right? Or it could be reacting to a fault in the caravan wiring...
However, I've also dismantled the 12N plug and tested the wiring inside. Using the circuit detection setting on the multimeter, I get a circuit between any two of the "positive" leads - that seems wrong.
Also replaced the 12N plug as the screw posts were rusted - no improvement. Some of the wires were bright copper, others were dull, even black (from soot?).
johnfryett said:
Cut the cable back and re make all of the connections, the ends of the wire will have corroded inside the insulation that's why it's black & sooty, all of the end's of the wire should be clean copper to get a good connection ..
In addition to the re-splaying of the male pins also try the following tweak for the female pins.
Make sure all the electrics to the plug are turned OFF. You don't want to short across two pins while cleaning!
Get an old wire brush (the heavy duty type with the wooden body/handle and not the fine suede shoe type).
Get some pliers and rip out one root's worth of "bristles". Try to keep the shape as round as possible.
Mount these root first into one end of a single large bore choc block connector and connect a piece of rod (bar, coat hanger, fencing wire or similar) in the other end. Remove the plastic if clearance is required.
This tuft of wires should fit in the bore of the female pin perhaps with a little twisting to lead it in nicely.
Twist it in there like a rotary wire brush to clean up the inside of the pin going up/down/in/out at the same time.
Make sure that NO wire strands or fragments from your new tool have become detached and remain in there thus posing an electrical short hazard.
Mount your new tool in a file handle and keep it in the toolbox.
Also consider that some cables where poorly supported might wiggle about and flex such that the internal wire strands become fatigue stressed and eventually snap. The outside of the loom may look perfect and not even chafed. The failure location can be extremely difficult to detect and so a replacement cable or a fresh single cable run adjacent to the main loom may be the only option in such a scenario. When installing a replacement single strand it is preferable to run it inside a sleeve of some sort (small bore plastic tubing like screen wash tube/industrial mig gas tube etc) to protect it. Also ensure that it is sufficiently supported. Also isolate the offending original circuit.
TX
Make sure all the electrics to the plug are turned OFF. You don't want to short across two pins while cleaning!
Get an old wire brush (the heavy duty type with the wooden body/handle and not the fine suede shoe type).
Get some pliers and rip out one root's worth of "bristles". Try to keep the shape as round as possible.
Mount these root first into one end of a single large bore choc block connector and connect a piece of rod (bar, coat hanger, fencing wire or similar) in the other end. Remove the plastic if clearance is required.
This tuft of wires should fit in the bore of the female pin perhaps with a little twisting to lead it in nicely.
Twist it in there like a rotary wire brush to clean up the inside of the pin going up/down/in/out at the same time.
Make sure that NO wire strands or fragments from your new tool have become detached and remain in there thus posing an electrical short hazard.
Mount your new tool in a file handle and keep it in the toolbox.
Also consider that some cables where poorly supported might wiggle about and flex such that the internal wire strands become fatigue stressed and eventually snap. The outside of the loom may look perfect and not even chafed. The failure location can be extremely difficult to detect and so a replacement cable or a fresh single cable run adjacent to the main loom may be the only option in such a scenario. When installing a replacement single strand it is preferable to run it inside a sleeve of some sort (small bore plastic tubing like screen wash tube/industrial mig gas tube etc) to protect it. Also ensure that it is sufficiently supported. Also isolate the offending original circuit.
TX
Hi Johnfryett don't know if this helps I had something similar happen on my way home last year on the a30 all lights when out down the O/S at 1 am so called the AA even he couldn't figure it out so fitted a bypass just to get me home just as he was packing up he came over opened the front locker had a look at the o/s front marker light something moved and had bent the connectors so were touching so the fault was showing all the time . bent back in to position and tape hope this helps
The conductors turning any colour - usually green or black - is down to water ingress. Unfortunately water will travel a very long way by capilliary action, so simply cutting back a few cms, will probably leave you in exactly the same position. Instead, expose a couple of cms of the copper strands, splay them out and rub one-way from the insulation with *fine* wire wool, turning as you go until clean and bright. Cut off any excess.
I know some disagree, but I have always twisted the wires then tinned with solder. Takes more time, but then I have never had 7 or 13 pin plug problems in all my years of caravanning.
I know some disagree, but I have always twisted the wires then tinned with solder. Takes more time, but then I have never had 7 or 13 pin plug problems in all my years of caravanning.
Once again, thanks to all who've responded. In an effort to isolate the fault, I decided to reverse the connections for the LH and RH running lights on the CANBUS box - this, of course, makes no difference to the lighting on the van. This appears to have solved the problem, i.e. the lights come on and stay on on both sides. I have no idea why this made the difference but, suffice to say, I'm leaving it like this!
I spoke too soon. Everything was fine for the first 80 miles or so. We stopped for a break and when we set off again, both sides stopped working after a few minutes. I've since done about 500 miles and the same thing has happened at every stop on the way. Worryingly, I believe that the brake lights are also affected but not the indicators. Off to buy a cheap multimeter...still, it's 30 deg C and I'm in France so not all bad.
So today I've spread out the wiring in the boot and noticed that the white wire leading to the CANBUS unit isn't connected to anything. I think it should be earthed to the chassis. Any advice welcome.
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