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The mkiv Supra Owners Club

Faulty bulb warning light conundrum


David P

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I discovered there was no warning bulb in the socket so fitted one.

Then found out that it was permanently on, even though all bulbs function.

 

I have subsequently, replaced the ECU that drives it and the scenario has become;

 

Ignition on light on, start engine light off, which is what it should do, however, first touch of the brake pedal and it is back on again.

 

All bulbs on the car are working and none are aftermarket LED's. :think:

 

The only thing I can think it could be, is how the importer has wired up the rear fog light function to a brake light.

 

Anyone with any ideas?

Edited by David P (see edit history)
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Blown brake bulb? :) Id on't know if you meant all bulbs in the dash are OK, or all bulbs in general.

 

The symptom you are describing is exactly what it does with either a blown brake bulb or low brake fluid (but that also comes on with slopes)

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That might be the case if they have put in the relay to have both lights on and then fog when button is pressed maybe the resistance throught he coil of the relay is enough to make it think theres a lamp out,

could difficult problem to over come as you would have to put back as stock to test then bypass each set of lamps to find where the fault comes or removes depending on if the fault was there after you put back to stock.

this could also be the guages if you havent run a seperate switched feed from the battery.

 

these are only my thoughts for things for you to eliminate as im dieing to see this beast :D

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Mmmm, I hadn't realised it could show up a fault from the gauges. :think:

 

However, the bulbs in anything and everything and the brake fluid level are all O.K. and my deduction is that it was the importer who had taken the bulb out to shut it up, which makes me suspect his fog light conversion.

 

I will look out for a stray relay whilst tinkering with the supercharger electrickery.

 

Thank you. :thumbs:

 

I am itching to get this Beastie breathing too, looking like Suprapod is to become the target date.

Edited by David P (see edit history)
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The bulb warning light comes on permenantly depending on which fog light mod you have done. If the importer done it, chances are it wasn't done with the wirewound resistor pack and therefor the fault shows.

 

Elementary :thumbs:

 

That sounds a highly probable conclusion.

 

Please tell me more about this wire wound resistor pack, I know nothing of these?

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I had a similar issue and found out you get the warning all the time when you upgrade a pre-facelift to facelift tail lights. Can't tell if you have facelift rears or not, but found this sticky on supraforums that sorted my bulb failure light always being on.

 

http://www.supraforums.com/forum/showthread.php?386061-Lamp-sensor-failure-indication-fix-after-97-98-taillight-swap-on-older-MKIV-s

 

Hope that helps.

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Mmmm, I hadn't realised it could show up a fault from the gauges. :think:

 

.

 

it may depend on if you have cut into the lamp circuit as there would be a un normal load on the circuit but depends how the system works , which i dont lol

 

how do your lights act to help find what way its been done?

 

both lights on with lights? or 1

both brake lights on? or 1

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Lights on = 4 lights.

Fog light on = 3 lights and 1 brake light.

Brakes = 4 brake lights

 

Where is this relay and/or resistor pack likely to be located?

 

 

I will go and read the thread, cheers.

 

 

Behind the boot panel. If you take out the carpet and the cardboard flooring you should be able to locate if it's there. It isn't the proper foglight mod though, as both would be lit (one on either side).

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