Technical Parking lights issue

[helgioiisac]

I’m experiencing an issue with the parking/side lights: they stay on even when the key is removed (the ignition switch is not in the “Park” position). The car has a custom wiring setup in the cabin. Here’s what I’ve observed:

• Removing fuse #10 (responsible for the cigarette lighter, radio, and interior lights) shuts off the parking lights and cuts power to the cabin.
• The left headlight mode switch has no effect on the parking lights — they remain on regardless of its position.
• When the headlight switch is turned OFF, the radio loses power (the orange control wire is no longer powered).
• Occasionally, the instrument cluster backlight also stays on unexpectedly.

These symptoms can appear and disappear on their own, without any clear pattern.
According to the wiring diagrams (assuming I understand them correctly), the orange control wire should only receive power under the following conditions:

a) The ignition is ON and the headlight switch is in either the parking lights or low beam position
b) The ignition switch is in the “Park” position


What really puzzles me is that removing fuse #10 (which, according to the wiring diagram, is for the cigarette lighter, radio, and interior lighting) also disables the parking lights — even though it shouldn’t be related to them.
Interestingly, removing fuse #2 or #3 also turns off the parking lights, but that’s expected behavior according to the diagrams.
It’s pretty clear that one of the previous owners must have done something wrong during wiring modifications.
At this point, I’m trying to figure out what exactly could cause this, and whether someone with more experience in automotive electrical systems might recognize the pattern or have seen something similar.

 

[LezLezLez65]

I’m experiencing an issue with the parking/side lights: they stay on even when the key is removed (the ignition switch is not in the “Park” position). The car has a custom wiring setup in the cabin. Here’s what I’ve observed:

• Removing fuse #10 (responsible for the cigarette lighter, radio, and interior lights) shuts off the parking lights and cuts power to the cabin.
• The left headlight mode switch has no effect on the parking lights — they remain on regardless of its position.
• When the headlight switch is turned OFF, the radio loses power (the orange control wire is no longer powered).
• Occasionally, the instrument cluster backlight also stays on unexpectedly.

These symptoms can appear and disappear on their own, without any clear pattern.
According to the wiring diagrams (assuming I understand them correctly), the orange control wire should only receive power under the following conditions:

a) The ignition is ON and the headlight switch is in either the parking lights or low beam position
b) The ignition switch is in the “Park” position


What really puzzles me is that removing fuse #10 (which, according to the wiring diagram, is for the cigarette lighter, radio, and interior lighting) also disables the parking lights — even though it shouldn’t be related to them.
Interestingly, removing fuse #2 or #3 also turns off the parking lights, but that’s expected behavior according to the diagrams.
It’s pretty clear that one of the previous owners must have done something wrong during wiring modifications.
At this point, I’m trying to figure out what exactly could cause this, and whether someone with more experience in automotive electrical systems might recognize the pattern or have seen something similar.

Hi, This may not be of use to you, but I had wiring on/off problems and there is correspondence and my eventual successful olution at https://www.fiatforum.com/threads/barchetta-speedometer-units.502542/#post-4696553. Hope it helps, LezLezLez65

 

[LeftyGreg]

For me, the problem is that you have as you describe a “custom wiring setup”

Do you have a wiring diagram for it.

My guess is that fuse #10 is a permanent live when the ignition of off and that has been used to power your parking lights

So, I would expect a non standard switch somewhere to turn parking lights on/off

A wiring diagram will show you that