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850 / S70 & V70 '96-'99 / C70 '97-'05 General Forum for the 850 and P80-platform 70-series models |
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Bulb warning - strange behaviourViews : 414 Replies : 4Users Viewing This Thread : |
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Feb 4th, 2019, 21:32 | #1 |
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Bulb warning - strange behaviour
Hi Guys,
A strange thing has just occurred with the bulb failure warning light on the dash. When I turn the hazards on, the bulb warning light also flashes, but all six bulbs (front / rear indicators and side repeaters) illuminate. However if I turn the hazards off and indicate left or right everything works as it should with no warning light. If I indicate left, the indicators and repeater on the left side all illuminate fine, as does the right when I indicate to the right. Any ideas ??
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Malcolm |
Feb 5th, 2019, 11:15 | #2 |
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Bulb Failure Warning
Does the bulb in the hazard warning switch flash? You don't mention that.
If not, then that is you problem. If it does then I would guess that there may be a problem with the flasher relay (I believe that there is a single relay for both hazards and indicators?). My first thoughts would be unplug the relay and plug it in again in case there is a dodgy contact. Next move would to try a known working relay, if possible. Another problem encountered on many cars is a poor earth on one of the bulbs where that bulb earths through another bulb circuit. HTH
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Turboboy Current: 1998 Volvo V70 2.3 T5 Auto. Previous: 2000 Volvo V40 T4; 1981/2 265 (x2); 1988 740 Turbo Estate. |
Feb 5th, 2019, 12:24 | #3 |
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Hummm, hadn't thought about the red indication light on the hazard switch.
Just had a look and this time when the hazards were enabled there was no sign of the bulb failure indication lamp. Seems the problem has resolved itself. Strange, them gremlin things......
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Malcolm |
Feb 6th, 2019, 08:41 | #4 |
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Highly likely to be either a bulb on its way out, or a poor connection on one of the bulbs.
The bulb warning system relies on there being a specific resistance in the indicator circuit, if the circuit's resistance goes over this or under this value, the system assumes it's because a bulb has blown and puts the warning light on. If you have a dodgy connection or a bulb whose resistance is out of spec then it can be enough to trigger the warning light. Sounds like you have a slightly out of spec connection or bulb, and when one side only is activated it's within the limits, but when all four corners are activated that's enough to take it out of limits and trigger the warning light. The bad connection may have temporarily fixed itself, but is likely to come back at some point. I'd start by taking ALL the bulbs out and cleaning the contacts - put them back in with a small wipe of Vaseline on the contacts, this will keep them clean and fresh for a long time, and inhibit any corrosion. When you do this, if ANY of the bulbs have any blackening of the glass (even if they still work) then replace the bulb - the blackening means it's about to blow completely. HTH Cheers
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Feb 6th, 2019, 20:46 | #5 |
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I get this from time to time, with mine the favourite place is on the back lights.
Not necessarily the bulbs but the holders can be a bit iffy at times as well.
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