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Discussion Starter #1
Has someone else experienced this?
When the temp outside is say 20F, the idiot lamp in the instrument cluster telling us that one of the outside lamps is out, comes on. I have got out of the car several times and checked all the lamps but nothing, not even one filament happens to be out.
When the weather is warmerm this does not happen.
Anyone else seen this strange occurance?
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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Do you get this as you go into gear.. If so it is the reversing light bulbs.. took me some time to figure.. start car use park brake into reverse.. get out have a look..
 

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You need to pull every bulb (don't forget third light) and licence plate and confirm it is the right bulb in the right place. I had an ongoing issue with this and discovered that the bulb in the third brake light position was 7W versus the 20W that should have been there. Also once I had a problem where a bulb would flicker after 10 seconds or so of using the brake light. First check all the bulbs for their type. Sometimes people might have stuck usa type 1057? bulbs in, that will lead to issues.
 

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1997 S600 (sold)
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Could be just a poor connection with one of the light bulbs.

The cold temps (shrinkage :) ) may make the problem worse. Check all bulbs and sockets. Clean off any corrosion. Make sure bulbs fit securely and make good electrical contact.

Good point made earlier about brake lights and reverse lamp bulbs. The dash light will only come on when these lights are in use, ie. only when you step on the brake pedal or when you put the car in reverse.

My dash light came on not too long ago. I found the source was the third brake light. Pulling the socket and putting it back in restored function for a couple of starts, but then it went out again. I finally pulled the light assembly and found that the fit of the socket in the assembly was poor causing arcing, which had eroded away part of the electric contacts. I was able to clean it up with sand paper and bend the remaining contacts enough to ensure good contact when the bulb socket was twisted into place. No problems since.

Brett
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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I use petroleum jelly..Vasaline .. just a smear..on the contacts...I find it stops the corrosion.. and the bad contact problems..
 

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Discussion Starter #6
The idiot lamp comes on only when the temp is very low outside and stays on. The lamps being used were the usual ones used when driving forward at 20-50mph.
That is why it could not be the reverse/stop lamps.If those lamps were the problem, the idiot lamp should go off when those lamps were not in use.
I was
Never happens when outside temp is more than 32F.
Let me wait for it to happen next winter!
 

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w140 s300turbodiesel
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What are the "usual" lamps being lit when driving forward 20-50mph? Headlights? Fog lights? High/Low beams? Daylight driving lights? Indicators? Were you braking? Knowing exactly which ones were lit when the warning indicator came on could narrow down your search area quite dramatically.

I used to have a problem with the inside left tail light. Contact in the socket seemed to be a bit problematic. Used a bit of contact spray and it hasn't happened since late december. Or it could be the low temepatures are helping keep the bulb tight in the socket, who knows...
 
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