Reversing /Backup light not working

[NADP555]

Hi guys very odd scenario and thought and advise would be much appreciated.

Vehicle Auris T180 UK spec.2007

  A number of years ago I fitted a reversing camera and took power for the camera from the reversing light wiring about 2 inches out from the white plug that goes into the multi bulb holder.  It has worked fine for years ( and I've not hit anything!!)

Just recently I'd noticed the reversing camera wouldn't always come on when selecting reverse so during our lockdown I decided to investigate further.

I noticed that the reversing light was not coming on, so my first thought was - Bulb gone, replace bulb and hopefully camera would work.  Changed bulb but still not working. I asked Motor parts stockist to check old bulb for me. That was working so the next obvious thing was to check fuse.  (I had'nt checked fuse first as to be honenst was 100% sure which it was. ) . Anyway fuse all OK.

Put a voltage meter on contacts where bulb sits and there is power there when reverse selected. What I noticed while doing this check that without the bulb in place, the reversing camera comes on but as soon as I put the bulb back in, the camera goes off and the bulb won't light.  If any wiring to do with the camera was shorting or anything, I would have thought it would have blown a fuse?

The camera power supply wire from the bulb wiring has a join in it with a connection under the hatch back before it gets to the camera itself. I've un plugged it at this point and plugged another camera in with the same results. I've done a continuity test from the join under the hatch back to where it connects in by the reversing light and that's all OK no short or broken wires. Also I have held the bulb to make contact with the metal strip on the bulb holder and had a wire to touch the metal tip of the bulb to the metal tip on the bulb holder but the bulb would not light up.

As a check on this test to see if I was wrongly expecting the bulb to light, I turned on the side lights removing the side light bulb and held the bulb side contact against the metal strip by the sidelight bulb holder and tip to tip connection on the side light socket and it lite up.  Using the same bulb on the reversing light bulb socket, the bulb did not light up. I have also disconnected the wires that  power the camera to elliminate  the camera wiring but still no joy.

My thought is the bulb holder itself, so my next option is to buy a new bulb holer unit but didn't want to go to that expense if you guys could come up with something obvious I've missed.

Sorry to be such a long post but trying to explain all tests I've done.  Again thanks to all who read this and are able to offer any advise.

Cheers  Nick

[Old Red Celica]

Is it earthing OK? Getting power to it is one thing but earth is just as important.

[Mooly]

As well as a problem with earthing it is also possible the reverse light switch on the gearbox is defective. The camera will use very little power indeed and so it is possible a 'high resistance' switch contact is the cause.

Now if that is the case then you have to ask why should yours apparently be the only one with a problem and I'm afraid that may come down to the wiring you have done... lets just say that without examination its an unknown.

The gearbox switch should be easy to locate and will just be a do-dah screwed into the casing. Do an image search for 'gearbox reverse light switch' and you'll see.

With the engine OFF and Ignition ON and the gears in reverse the lights (I think) should still be on. So you can check it that way. The switch should close to light the bulb. If the switch has varying voltage across it as you fit and remove the bulb then the switch has gone high resistance.

Fwiw I had the reverse light switch fail on a Audi A4, just one a raft of issues, but the symptom initially was one of radio interference. Put it in reverse and it cleared. Good eh! The contacts had carbonised and were arcing internally. The switch failed completely some weeks later.

 

[rajivrattna]

My guess is the faulty bulb holder.

[NADP555]

Just picking up on all replies, so that's for all feedback/info will work through all suggestions and hopefully get to the bottom of it!

Cheers

 

[NADP555]

Hi Guys

Many thanks for all advise to my above issue.  It has now been resolved so thanks for the pointers.  It turned out it was the reversing light gearbox switch.  I did a search on the internet on how to get to it and the video I found was to take the air box off, clips etc to get to it.  I'm afraid I was a little put off by this so chickened out and took it to an auto electrician who £66 later confirmed it was the switch.

They didn't have one but could get one in the following day.  They did show me an alternative route to getting to it.  Taking nearside wheel off and popping the panel off and it was there right in front of you.  So I did exactly that.  Ordered the part myself £14.40 and once I had the wheel and trim off, it took a minute to replace. 

All good, just sorry I didn't know the side access route before!  But thanks once again for all knowledge passed on.

Wishing all a Healthy , Happy and safe New Year!          Happy Christmas - Well it is nearly December!