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1995-2002 Range Rover Classic
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Discussion Starter #1
Over the last 18 months or so my 2k p38 has developed an affinity for right front fog bulbs. I have installed regular standard filament halogen replacement bulbs as well as Led's with similar results.

it could take as short as 1 week or as long as 2 months, the right front fog goes out and as normal it sends the bulb out signal. the left front is what the truck came with when I acquired 2 years ago, so far it has not failed. strangely only the right front.

I have not physically inspected the wiring or the circuit but here is my hypothesis, a possible defective right front fog relay in the becm which may be causing the bulb to flicker emulating on/off cycle thus early failure (according to rave there is a relay for every fog lamp as well as a separate circuit to each).


My possible approach at repair, 1-) trace wiring and see what is happening (I have cleaned the grounds, no solution). , 2-) run an overlay circuit from BECM to right front fog in order to verify BEcm internal failure or lack there of., 3-) install a resistor of bulb value on right side circuit in order to fool BECM and rewire a jumper from left fog circuit to right fog and hope for resistor to hold, thus avoiding bulb out message.

has anyone ran into this or a similar failure?, what was your repair?.

thoughts, insights, comments, ideas, all welcome.

Thanks
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,224 Posts
All of the lights are driven by solid state MOSFETs in the BECM, rather than relays. It is possible for these to fail, but they generally fail in an 'off ' state, so that just nothing will happen. The tracks in the BECM for the lighting outputs are fairly hefty too, so whilst not impossible that is the problem, I'd say it's unlikely.

I would be checking the wiring from the BECM to the fog lights - especially paying attention to where the fog lights plug into the vehicle loom. I've found a couple now where the pins in the connector on the vehicle side of the loom are starting to corrode and either causing no connection, or a high resistance connection back to the BECM, and sometimes this affects the fog light coming on.

i'd start with that, and go from there.
 

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1995-2002 Range Rover Classic
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1,413 Posts
Discussion Starter #3
thanks Marty, will check as soon as weather permits. the oddity is where this is the only bulb which physically burns, all others never fail.
 

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1995-2002 Range Rover P38A
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1,422 Posts
Interesting issue, If it was April 1st, I would say "Good One!"
You say you are blowing both incandescent as well as LED elements?
Led's in particular will generally have no issues with cycling rapidly. By design, It is called Pulse Width Modulation, and is the usual way they are dimmed. If, however you have a cheap LED bulb, the "Cheap" part is usually the driver electronics. Those may be unhappy with being switched on and off rapidly.
Under driving Halogens will also cause early failure, but you would notice the difference in brightness immediately. also it could take years to fail a halogen due to undervoltage.
As Marty says, check the wiring, as in this case, just about the only thing that will provide high frequency intermittent power is an arc, which will be obvious as, by now, the connector should be just about non existent due to the very high heat.
 
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