Small parking light problem
 

I noticed the other day that my right side parking lights, fore and aft, were not working. I looked at the fuse box and the left and right sides have their own separate fuses. I checked the fuse for continuity and it was good. So I checked the power supplied by the grey wire on top of the fuse and it read only 5 volts. I checked the supply wire for the other side of the car and it read the correct 12+ volts. ???

So I temporarily ran a jumper from the left side fuse to the right side and now all my lights work. It's not a big issue as I rarely drive the car at night or early morning. But anyone have any idea why the supply wire would read 5 volts with a fully charged battery? (I thought I had a PhD in odd auto electrics, having misspent my youth with 60s British cars, but this one has me stumped).

Is this effect when the engine is running? When parked engine off, only 1 side will come on depending on your direction indicator position. European system!

lights.
 

Those are called "Standing" lights.

Intended for illumination while the car is parked at night.

The 5v may be an energy conservation idea.

Best,

Gerry

Nope. I checked that first. This is with the ignition on or off with the turn signal in the center position. Headlight switch pulled to first detente.

Check the other side of the fuse block for 12v. I think you are checking the output side. It is probably a bad connection at the fuse block or where the fuse itself makes contact (or possibly a damaged fuse). Check, clean and tighten the connections and the fuse. Try swapping the fuse with a known good one.

The Park light power feeds come via the light switch and indicator switch, lots of places for a high resistance contact or dodgy connector to drop the feed voltage. Even the bulkhead connector could be corroded. I suggest you position a mirror so you can see a park light and start wiggling connections, operating the light switch etc.

There's a diode, 86 only, just off the light switch, inline to the right park lights. It burns out. Replace or just bypass.

What was the logic behind that!

I bypassed mine
I forget why it is there, I would have to look at the diagram to remember.
don't hold me to it, (from memory) it may be there so when you use the right side park lights (with the turn signal) it does not turn on the license plate light.