Technical Another problem number plate light warning light is on

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Technical Another problem number plate light warning light is on

Dave4677

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Hi all i put my lights on today a warning light came on CHECK number plate light so i did that and the I checked the back and the left light was out got halfrauds to sort it and bought some led bulbs there now both working but the message still pops up and amber warning light is on still any idea? Much appreciated people
 
Only when engine is started however when turned to Mar and lights on it didn't seem to pop up
 
Hi Dave and All, let's go back to school once again...

Theory:

To ease calculation, let's pretend each bulb is 12 watt, the current sent to the rear plate would be 2x 1 amp (12w / 12v = 1A) = 2 amps since there is only one wire going there.

Problem:

If the Body computer detects less than 2 amps, it triggers the error. No CAN involved here (only between NBC and the control panel's light).

Reason:

The LEDs draw about 1/5th current for the same brighness (let's pretend it again); the total current drawn is 0.4 A : check rear plate light ON.

Solution:

One need to install something that would draw 1.6 A (2 - 1.6) on the same line as the LEDs; a simple resistor will do the job !
What values ?? ohm's law is U=RxI, or R=U/I : 12v / 1.6A = 7.5Ω that is a standard value for a E24 serie resistor; would be 6.8Ω or 8.2Ω for the E12 serie... This resistance needs to be connected between rear-plate (F050 & F051) lights positive lead and ground (C030), in parallel with the load.

Warning:

The resistor will dissipate (P=UxI) 12v x 1.6A =19,2 Watts, which basically is what would have been wasted in heat within the normal bulbs, so it needs to be well sized (power-wise) and ventilated (not enclosed in plastic box...)

Conclusion,

The values I used need to be adjusted to the actual ones, the best being to measure what actual current is drawn under what voltage. The calculation is valid for any bulb, just need to adapt the values and also the circuitry...


BRs, Bernie

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