Good evening

My first post for some time - largely due to an MBG rebuild! Recently however I’ve had an issue with the generator light:

Last week I replaced all bulbs with LEDs (excl. headlamps, which remain H4) and since then a good shove of revs are needed for the generator light to go out. I’m not sure if this is related to recent swap of lamps or not.

Once out, revs can drop to a level (above idle) and the light stays out. If the light was not already out then this level of revs would not cause the light to go out. Engine is 650cc with refurb’ alternator and voltage regulator form Ricambio some six years ago.

Separately, the horn contact is temperamental - how easy a task is it to dismantle and re-tension/ brush the contacts?

Many thanks
Steve

Did you perchance replace the ignition light with a LED bulb? If you did, that could be the problem. I fitted a LED bulb to the ignition light in my 'Abarth' style instrument cluster---took me a fair amount of time and a lot of frustration to sort out the problem. only rectified when I fitted a 'normal' bulb.

Assuming you've checked the alternator output and it's within tolerance, it's likely due to the nature of LEDs. Your voltage draw is certainly less with them, but they are an 'all or nothing' level of light. Incandescents will light up less with lower power, whereas LEDs (unless they are dimmable) will be either off or fully illuminated. You could be seeing this - a situation where you old incandescents would barely be lit, but the LEDs are fully on.

Check you alternator output - you should be putting out ~13.5-14.5 volts.

As for the horn, it can be finicky, but is easily disassembled to clean the grounding contacts. No need to remove the wheel, just pop the centerpiece open and you can access the grounding ring. I've found that electrical issues in these cars are almost always related to grounding issues due to old wiring, poor grounding points, or convoluted circuit designs. Look at the wiring diagrams and be methodical in tracing your circuit. It's a pain, but almost required routine maintenance on these.

Yes, I did indeed fill the dash with LEDs, and so that’ll be the issue. Thanks both for the quick replies and it is a relief it’s that straightforward. I’ll swap the G light back to the previous lamp in the morning.

Great to hear the horn isn’t a wheel off job l, and something I’ll also take a look at tomorrow [emoji106]

The charge bulb load acts as a exciter current to the generator
Replace that one with a bulb and all should be well