Right Headlight Lighting, But Dim
05-03-2005, 01:50 PM
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Right Headlight Lighting, But Dim
My brothers 1983 928S has a strange problem going on. The right headlamp lights, but is very dim. Does the same with the old and new light installed, and on high and low beam. These are the standard headlights, no H4 upgrades or anything.
It's got me stumped. Any ideas people? I hate freeking electrical problems.
It's got me stumped. Any ideas people? I hate freeking electrical problems.
05-03-2005, 01:59 PM
#2
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Sounds like you have a high resistance in the line somewhere either on the 12V line or ground line.
You could get into the headlight pod and ideally measure the voltage level to ground on both side of both bulbs when on - but given its seen on both high/low it sounds like a common ground problem.
An option to validate is to provide a clean ground to the bulb to test this fixes the issue...
It may be easier to just directly trace the grounds and clean them up - you are dissipating some power into this resistance - many watts even at reduced power - so there may well be some significant heating effect when on for a while - this may help the location search. Check the FWM for the ground points you need - I've never done this specific fix so I'm not sure where...
Alan
You could get into the headlight pod and ideally measure the voltage level to ground on both side of both bulbs when on - but given its seen on both high/low it sounds like a common ground problem.
An option to validate is to provide a clean ground to the bulb to test this fixes the issue...
It may be easier to just directly trace the grounds and clean them up - you are dissipating some power into this resistance - many watts even at reduced power - so there may well be some significant heating effect when on for a while - this may help the location search. Check the FWM for the ground points you need - I've never done this specific fix so I'm not sure where...
Alan
05-03-2005, 03:03 PM
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The usual cause for this is a loss of the ground connection. The hi and low filaments in the bulb are connected to a common ground (the three bulb connections are power to hi, power to low, and common ground).
When you lose the connection to body ground, the voltage to the low beam filament will flow thru the low filament to the common bulb ground, then back thru the high filament, thru the wiring to another bulb, thru that bulb, and to ground.
The same thing can happen on one of the two-filament tail/brake light bulbs.
When you lose the connection to body ground, the voltage to the low beam filament will flow thru the low filament to the common bulb ground, then back thru the high filament, thru the wiring to another bulb, thru that bulb, and to ground.
The same thing can happen on one of the two-filament tail/brake light bulbs.
