Technical Another number plate light query

[HWJTD]

I seem to have a problem that differs from many of the other number plate light issues. I'll bullet point my lack of progress so far:

1. Dash warning light said to check number plater light
2. Replaced bulbs with LED canbus bulbs, worked flawlessly for 6 months
3. Warning light reappeared
4. Wiring from the boot lid loom to the lights checked, no damage
5. Replaced LED bulbs for standard bulbs, cleaned up connections and warning light disappeared AND everything seems to function as normal.

seems like a fix?
Not quite, I still get a reading of 0.6 volts when bulbs are in place and the whole car is switched off, even when locked.

I know there must be a problem somewhere along the line, but how can the bulbs still be receiving power when the car is off? Albeit, not enough power to light the lamps.

Any expertise or experience with this problem is greatly appreciated.

Side point - there doesn't seem to be a fuse associated with the number plate lighting the lights still operate when the boot lid button fuse is removed.


Howard

 

[SGThirkell]

I seem to have a problem that differs from many of the other number plate light issues. I'll bullet point my lack of progress so far:

1. Dash warning light said to check number plater light
2. Replaced bulbs with LED canbus bulbs, worked flawlessly for 6 months
3. Warning light reappeared
4. Wiring from the boot lid loom to the lights checked, no damage
5. Replaced LED bulbs for standard bulbs, cleaned up connections and warning light disappeared AND everything seems to function as normal.

seems like a fix?
Not quite, I still get a reading of 0.6 volts when bulbs are in place and the whole car is switched off, even when locked.

I know there must be a problem somewhere along the line, but how can the bulbs still be receiving power when the car is off? Albeit, not enough power to light the lamps.

Any expertise or experience with this problem is greatly appreciated.

Side point - there doesn't seem to be a fuse associated with the number plate lighting the lights still operate when the boot lid button fuse is removed.


Howard

Hi, just a thought but it may be the "stored" voltage in the LED circuitry showing 0.6V.
Remove the LED and measure at the empty holder to see if the voltage is there then. If not, that's it. You could even check the LED while it's out and it should still show 0.6V stored in it if that's the case.
May not be but worth investigating to rule it out

 

[HWJTD]

I think there was some of that happening, but I removed the LEDs for standard bulbs and I'm getting voltage.

More recently, I've removed the bulbs and get a reading of 8v but I think I know what's going on. The 8v charge lasts about 2-3 mins and the goes to 0v. Having recently found out that the lights are controlled by the car's computer, I assume that this is just residual charge from the computer? And is probably normal.

 

[HWJTD]

And also, I've removed the fuses one by one and the charge did not change

 

[SGThirkell]

I think there was some of that happening, but I removed the LEDs for standard bulbs and I'm getting voltage.

More recently, I've removed the bulbs and get a reading of 8v but I think I know what's going on. The 8v charge lasts about 2-3 mins and the goes to 0v. Having recently found out that the lights are controlled by the car's computer, I assume that this is just residual charge from the computer? And is probably normal.

Oh I see, sorry. I suppose that if it does go to zero then all is ok anyway.
One thing I can maybe add is that it is possible to have a voltage there without any significant current drain (without going into electronics technical terms) so won't drain the battery if this is the case. If there was any current drain (load) then the bulb would be lighting up at this time, do you get me?