Reverse Lights Not Working

[GarryB]

Hi,

 

Has anybody got any good ideas as my revers lights aren't working.  I read lots of info on the forum but not got a fix as yet, I'm now going mad.

 

I have tried the switch - MkII so removed battery tray - switch is working OK.

I have looked at the wiring in the connections by the rubber boot at the top of the door - not conclusive but all looks OK.

 

The parking sensors don't automatical switch on when reverse is selected unless...  I tried disconnecting a plug in the boot storage area and the parking sensors automatically activate.  So followed on with this thought and have got to the stage where the parking sensors activate when reverse is selected if the reverse light wiring circuit isn't complete.  If I remove only the bulbs the sensors activate.

 

With the bulbs removed I get 12V on the bulb contacts when reverse gear is selected.  This looks to be good but when the bulbs are put in....nothing and the parking sensors don't activate.  The voltage across the bulb is only 0.1V.  The 0.1V disappears when reverse gear is deselected.

 

I have swapped the bulbs out but now can't think of anything else to check.

 

Has anybody got any ideas.....please.

 

Garry

[chrispb123456]

I would say your problem is still the wiring in the gaiter, where you unplugged in the boot use a 12 volt 21 watt test lamp this will put a load on the wiring which a voltmeter doesn't, if the bulb light at this point you know the problem is at the gaiter or in the door.

[SilverBeast]

Still most likely to be in the tailgate gaiter as chrispb123456 has suggested.

 

One other possibility is if you have a towbar fitted.  Some of the tow sockets have a switch inside that disables the reverse parking sensors and the reversing lights if you are towing, though this would probably only be on a factory fitted towbar, as extra wiring and programming of the dash is required.

[SilverBeast]

Forgot to say, switch may have stuck/rusted up causing them to be permanently disabled.

 

Second thoughts as you have 12V when bulb isn't fitted then I would say it is definitely a not quite broken wire as I had similar on a trailer socket wiring problem.  Basically the wiring has a higher resistance than the bulb so the energy gets disapated in the break instead of the bulb.

[GarryB]

Thanks SilverBeast,

 

I think you right with the not quite broken wire.  The issue was intermitant but is beginning to seem more permanent. 

 

I have just tried the bulb idea with the multi plug in the rear disconnected.  Still the same 12V then nothing when a bulb is connected. I guess this rules out the tailgate wiring but leaves wiring from the switch to the rear of the car. 

 

Next I think I'll get the battery and battery tray back out and connect as close to the switch as possible and try to narrow it down that way.

 

I will get a bulb to light!

 

Thanks for your thoughts.

 

Garry

[viperclive]

An idea! Having repaired and replaced all the wires within the rear boot, and joining them inside rear right hand pillar under trim, I would remove trim find the wire coloured sw/b1, which is blue/black, pick up a + supply (from rear cig lighter), connect to wire mentioned, if wiring in rubber boot is ok and fitting has an earth they should light, if they do and stay lit with door being opened and closed then you can concentrate all your attention to switch. If no light then no earth or broken wire in boot.

[GarryB]

Finally sorted.  I think I've learnt a good lesson here.  I had previously relied on my meter to beep indicating that a connection was good.  As note above there was a suggestion that I'd got a partially broken wire.  I carried on checking all sorts of stuff, leading abck to the switch.  The switch was my 1st thing to check.  The meter beeps when the switch operated so I moved on.  On closer inspection it was reading 30 Ohms - much higher than a bulb.  This was the almost broken connection, not the wiring after all.  I used an old toggle switch to make a temp solution.  All worked well.  Now replaced the switch properly.  All working well!!!!! 

 

A switch not quite making a proper contact.  Sealed switch so can't see what has happened or clean the contacts.  Happy with the result though.

 

I will check readings in future not just listen to that beep!

 

Thanks for the thoughts and help above.

 

Garry

[SilverBeast]

Glad your sorted. Well done.