Strange bulb issue - any experts???
Discussion
I have a 2001 Octavia VRS. It has quite large headlamp units, containing a normal 55/60w H4 bulb, and a small 5w capless sidelamp bulb.
Recently, on the off-side unit, the sidelamp bulb had become noticeably dimmer than the nearside. I put it down to old bulbs.
I bought a nice pair of Bosch replacements, because I'm anal like that and I need symmetry in my lamps, Godammit!
When I removed the old bulbs, the off-side one had become darkened inside the glass for some reason. When I replaced them with the new ones, all was fine again.
Until about two months later - and now the off-side sidelamp bulb has AGAIN gone dim with the same issue.
What gives??
Recently, on the off-side unit, the sidelamp bulb had become noticeably dimmer than the nearside. I put it down to old bulbs.
I bought a nice pair of Bosch replacements, because I'm anal like that and I need symmetry in my lamps, Godammit!
When I removed the old bulbs, the off-side one had become darkened inside the glass for some reason. When I replaced them with the new ones, all was fine again.
Until about two months later - and now the off-side sidelamp bulb has AGAIN gone dim with the same issue.
What gives??
In some failure modes, 501 sidelight bulbs like that do start to darken gradually, almost as if they're filling with smoke. When one had blown and I was replacing a pair, I'd often find the still-live one was starting to darken in that way and took it as an indication that it didn't have long left.
I haven't known a new-ish bulb start to do it, only on one side of the car, though. Usually this would be a more immediate failure. Quite odd. I would leave it alone for a while and see if it blows again. Some cars (I mean individual examples, rather than by model) do have a propensity to kill off one particular bulb more often than they should. Usually seems to be due to earthing problems, but like I said, I haven't known them cause this darkening, they tend to just blow things at a stroke.
I haven't known a new-ish bulb start to do it, only on one side of the car, though. Usually this would be a more immediate failure. Quite odd. I would leave it alone for a while and see if it blows again. Some cars (I mean individual examples, rather than by model) do have a propensity to kill off one particular bulb more often than they should. Usually seems to be due to earthing problems, but like I said, I haven't known them cause this darkening, they tend to just blow things at a stroke.
Its the element running hot and boiling off then condensing on the glass. a high resistance earth cant cause this, but an intemittent one would. When a filament is cold it has a lower resistance so you get a current inrush, thats why light bulbs often go "ping" as you switch on. So a cycle of losing contact, making again and current spikes would do this. I would try cleaning the socket and maybe tweaking it a bit to get better contact if possible.
Ray Luxury-Yacht said:
Hmmm, ok - so might be worth checking the block connector to the unit and doing an earth continuity / resistance check?
I'd check the plug, it may well be causing a tiny area if high resistance or even arcing and the associated high temp being transferred into the bulb?normalbloke said:
Ray Luxury-Yacht said:
Hmmm, ok - so might be worth checking the block connector to the unit and doing an earth continuity / resistance check?
I'd check the plug, it may well be causing a tiny area if high resistance or even arcing and the associated high temp being transferred into the bulb?I'll have a butchers tomorrow
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