Faulty reversing light

HiddenMission · Post by **HiddenMission** » Sun Mar 25, 2007 4:59 pm

I have a dud reversing light on the driver's side - the bulb seems fine (I've tried a replacement), and I was wondering if anyone had any ideas what might be causing the problem. The connections also look fine, as far as I can tell withouth stripping them right back.

mikeonb4c · Post by **mikeonb4c** » Sun Mar 25, 2007 7:18 pm

I keep meaning to get myself an avometer so I can test circuits and stuff to see if they are live. I would think circuit testing might be needed in order to eliminate causes?

HiddenMission · Post by **HiddenMission** » Sun Mar 25, 2007 9:56 pm

I'm not particularly electrical, so how would this help? Surely I already know that the circuit doesn't work? Is there a standard approach to dealing with this sort of problem?

pippin · Post by **pippin** » Sun Mar 25, 2007 10:38 pm

Yes there is.

Not being sarcastic or demeaning in any way, but that is what electricians and more specifically auto-electricians spend time at college learning.

Anyone who has done any physics at school (more than twenty years ago) would also have a fair idea of where to start.

mikeonb4c · Post by **mikeonb4c** » Sun Mar 25, 2007 11:12 pm

I sympathise HiddenMission as I am not v electrickery minded either, although I did an A Level in Physics years back so know what I ought to know, if you get me. I think what Pippin is confirming is that you have to have a reliable testing device (2 wires and a bulb in its simplest form) that you can place across the + and - at various points to establish exactly where the power supply failure is occurring. However, with any luck someone on BF will come back with an answer like 'oh I had that problem and I traced it to the etc. etc.'. If you get an answer like that, great and you can check yours and see if it gives a quick solution to the problem. Otherwise, detective work of a methodical nature and with a circuit tester will be required.

Good luck

Mike

HiddenMission · Post by **HiddenMission** » Wed Mar 28, 2007 12:12 am

Thanks - I actually posted this question to see if anyone had had a similar problem they may have fixed, or could point me towards some practical advice for how to tackle the problem myself.

Despite having done physics at school just over 20 years ago, but no didn't go on to study auto-electrics (thanks for that helpful insight), I can't really think how to start. Put that down to my lack of applied electrical knowledge if you will, but that aside, I would just be grateful for some abc style pointers as to what to try next. If you are suggesting that it's best to leave it to an auto-electrician then fine, I'm happy not to waste any more of my time. It took long enough just working out how to get the light unit off

Post by **Simon Jones** » Wed Mar 28, 2007 8:06 am

HM - just a thought, some of the convertors (like 321) replace the drivers side reversing light with a red bulb, or spray the lens red so they can re-wire it as a fog lamp. See if you have a switch on the dashboard that either has a suitable symbol on it, or more likely it will be an illuminated switch which will not look the same as the others. Turn the dipped beam on & flick the switch - if the "reverse" light comes on red, then that is the answer.

Not sure where in the country you are, but I'm sure some local Bongo owner would help you out if you need some more technical assistance.

mikeonb4c · Post by **mikeonb4c** » Wed Mar 28, 2007 8:52 am

To condense the above

A - get a circuit tester
B - test along the wiring route to establish where supply failure is occurring
C - call us any time you have problems with that

Hope that is practical enough

Good luck

Mike

HiddenMission · Post by **HiddenMission** » Wed Mar 28, 2007 10:44 am

I'm really labouring this so apologies:

I should have asked first of all whether the faulty light is actually a problem at all - is it an MOT fail?

Simon, your explanation looks a likely one (the red bulb), I'll check for the switch you describe, but not immediately aware of it.

Mike, on the circuit testing, my bafflement is that the only bit of the circuit I can easily access is the bit sticking out of the light unit. Once it disappears into the body of the vehicle, I'm a bit lost!

Thanks for the tips

pippin · Post by **pippin** » Wed Mar 28, 2007 11:57 am

One might assume that the reversing light is turned on by a switch that is operated by the gear selector lever, so that could be a place to start.

However in these days of high technology, it might actually be turned on by some complex electronics to do with the auto gear box.

The annoying beeps must be triggered by it too.

So, a simple fault might have an obscure origin, or it might be a simple break in a wire somewhere.

That is why some sort of test equipment and possibly access to the wiring diagrams is really necessary to sleuth this out.

It is the sort of fault that an expert might find in a matter of moments due to "sixth sense" or on the other hand that same expert might have to spend hours tracing it.

bigdaddycain · Post by **bigdaddycain** » Thu Mar 29, 2007 12:45 am

The bulb is probably "not quite" making contact in the housing. Try taking the bulb out, then ( with ignition off!) gently easing the "springy" contact towards you. If you can get it to stick out a bit more, the added spring effort may be sufficient to give the lugs on the side of the bulb more purchase in the housing. You can test for a bad contact without all the electrical diagnostics, just remove the lens,turn on the engine,select reverse,( get someone on the footbrake) and ease the bulb further in the holder to see if you get a glimmer... try not to touch any metal,use your thumb on the glass of the bulb...