Bit of a problem on the missus's Agila, with lights on the right rear tail light goes out when you press the brakes, so when braking you just have the left tail & brake light lit up, nothing on the right, with the tail light coming back when the brakes are off.
I whipped off the cluster & changed the bulb, but the same result. A wiring problem somewhere, but I'm not sure where. My days of back breaking DIY repairs are over, so it's not for me if it's around the brake pedal area.
Anyone have any ideas on this? It's going in for a MOT soon, so could get it looked at then, but if I can save a few quid....
Best guess from here is a weak earth connection, capable of carrying the current of the tail lamp, but unable to cope with the higher current of both.
Start at the bulb; clean the bulb housing where the connection is made, then check the earth wire to the cluster. Disconnect and clean where possible. Then follow the loom back until you find an earth point. Again, disconnect and clean.
Cluster earth fault. Basically the lamp cluster has completely lost its earth connection at the rear. Confirm it by simply adding a wire link between the earth point on the cluster, back to be good earth.
If it has *completely* lost its earth connection, how does the tail light still work?
On the not unreasonable assumption that it uses a dual filament stop/tail bulb, if the poor earth connection is within the cluster, adding a temporary earth to the cluster connection won't make a blind bit of difference.
Via the stop light filament at the same side, through to the stop light filament at the other side, then via that to it's earth connection.
That will very much depend upon where in the cluster the break in the earth is, assuming it is in the cluster. I'm the OP is bright enough to try taking the temporary earth to the lampholder if necessary, given the provided clues.
Hey, thanks for that, I didn't think it would be something so simple, I gave the earth>bulb connection a scrape with the screwdriver & it snapped off. Easily bodged for the time being by stuffing tinfoil in the side of the bulb holder between bulb & remains of the connector & it now works fine.
The lamp had lost its original earth, the one which it was designed to have by the manufacturer. It was managing to find an alternative earth via an unintended route.
The point I was making was that there had to be *some* connection to earth for it to work at all. I fully understand how trivial circuitry like this works; I spent 35 years as an industrial electrical technician, and have been fannying around with cars for half a century. The OP, OTOH, clearly doesn't have the benefits of that experience, or he wouldn't be asking on here. For him, and others, it's important to explain clearly.
And as anyone who has messed about with electrical gear knows, there is danger in alternative earth paths. ;-)
I once completed a 300v earth path to my receiver, via a coax plug in my right hand and the receiver case on which my left hand was resting. I stopped breathing for a couple of seconds until I snatched my hand clear.
In a vehicle driven by petroleum spirit, and containing complex electronics, there are other dangers in unintended earth paths, I would guess.
Steady on fellas, it's only a tail light, let's not fall out.
I just thought I'd add that the connector is the bent over strip of metal type which has a spring effect, thus putting some pressure on the bulb's side. It snapped off at the bend, which would be the weak earth that was so well explained. Thanks again for the help, I've seen this problem on cars I've been following, but never owned one with the problem in my 25 years of fannying around with cars.
I fully understood your point, but none the less there was an earth missing - a point intended to be earthed lacked its intended earth, the current therefore took a route to earth it was not designed to take.
Yes it is trivial, but so is this discussion.
You do not need to provide details of your experience, to make your posts appear more valid.
Which was why I suggested a means by which the OP could begin to trace the problem.
I don't consider it trivial to clarify a point that might confuse anyone trying to follow what you said,
I didn't; I did it to make the point that this ng is open to users with a wide rage of abilities and knowledge.
However, what you posted would not have enabled him to find the fault, might have caused further problems, and in any case I had already given him the correct information more than an hour previously.
The argument is on the technical description of the fault was trivial.
I do of course have no objections to your expanding on my explanation, but you were not expanding - you were suggesting I was wrong, later trying to force the point home by providing your qualifications and experience.
Sorry, but I cannot quite believe that.
If I were aiming a reply at someone inexperienced, I would do it a step at a time and have them report back with their findings at each step. I provided the OP with one single step and a brief description of the suspected problem, enough to get a more knowledgeable friend working along the right lines to resolve the problem.
On Sat, 17 Sep 2011 17:33:34 +0100, Harry Bloomfield dribbled:
Who cares what you believe? Chris was being helpful, the OP understood it perfectly. As always, you have to post some holier-than-thou condescending waffle to big yourself up.
Ah the joys of Usenet. However it does remind me of my wonderful old Marina
30 some years ago when I was training to be an ACA. The wires to the rear lights just ran unshrouded across the back of the boot so if you had anything in there and did a bit of enthusiastic cornering, or even any cornering, the luggage tended to rip the wires off the sockets. We were coming back from an audit late one night with three other people in the car, my manager and two other trainees, and a boot full of boxes of audit papers. As I exited the Denham roundabout to head to Rickmansworth I spotted a cop car hiding behind a bush. "That's us about to get pulled over" I said because plod pulled me over every bloody time they saw the car. Eight times in two years I think it was mainly because they thought nothing that looked so shitty could actually be roadworthy although underneath the rust it was actually in fine nick.
So sure enough the blue lights come on and I pull over into a layby with them behind me. A lady cop was driving and her young protege who appeared to be about 12 and had probably not yet started shaving got out and informed me I had a stop light not working. No great surprise with all the boxes sliding about in the boot. So I took the key out of the ignition, opened the boot and had a fiddle about with the wiring in the pitch black. "Do you think you've fixed it?" asked junior plod and I said I couldn't be sure. So he got into the driver's seat, said hi to the other three bemused passengers, pressed the brake pedal and asked me if the lights came on properly. Now anyone with a brain would have asked me to press the pedal while he looked at the lights but this guy was so thick he didn't think of that. "Anything?" he asked. "Nope" I said honestly as now neither brake light was working to my considerable consternation. "That's good then" he replied having clearly misheard me, got back into the plodmobile and to my astonishment they both just drove off.
"WTF just happened there?" I asked the others as I climbed back into the driver's seat. "Not surprising no lights worked at all" said one of my colleagues, "you had the ignition key with you. The electrics were all off." We waited until they were well out of sight and then drove home without further incident. I found the loose wire the next morning. I wonder if that young trainee plod ever made it to to be a fully qualified plod or whatever plods do. Clearly the entrance examinations aren't that strict. I think you have to spell your own name correctly but that's about it.
Some days it seems that about 10% of cars have one brake light out. Ever told a driver? - you normally get an apathetic response. ("Its in for an MOT in a couple of months - they will sort it")
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.