Turn signal always illuminated when headlights on

They're behind the control panel on the forward centre console

https://www.dropbox.com/t/JHzgHyMYL0aCIp4u

This USA lighting diagram is incomplete, but the relay wiring should be ok.

See relays 210, 209 and 208. Soldered in place and not easily replaceable. 208 is the power relay which selects where the turn signals get their power from ... either from the hazard system or the normal turn system.

 

Now that you mention it, I can't see how the front flasher lights are activated with the hazard lights on. e.g. Relay 209 seems to only power the right hand rear light.

On the 348, do only the rear lights flash when the hazards are turned on?

Could relay 209 be stuck on? But why should it get power when the sidelights are turned on?

 

Disregard. I see that a jumper wire in the steering column provides power to the front rh turn light (from relay 109). Back to the drawing board....

 

Does the flasher unit provide a constant flashing signal whenever it is powered? It only seems to have 4 pins on it. Power in, earth and two outputs.

But it always has power on it. The signals don't go anywhere, though, unless the turn or hazard lights are turned on.

 

Perhaps it only flashes when the module output pins are connected to the lamps (via the column switch or console relays).

 

Yes, the flasher relay will only "flash" when there is load connected to it via the column switch (left or right indicator lights) or by the hazard switch (the three small relays activated by the single push-button switch) connecting all indicator lights to the flasher relay. The three small relays actually perform the same kind of switching as the old fashioned mechanical hazard switches do (in the case where one flasher relay is used for both, the indicators and the hazard).

Otherwise, on the 348, while the hazard lights are "on", the indicator function (the column switch) is inactive by design, i.e. there will be no automatic changeover from the hazard to the indicator function when you move the column switch to the left or right (and back to the hazard function when the column switch is back in its middle position).

 

Agree -- I had (wrongly) thought that something could be wrong with relay 209 (but then the RH turn indicator in the dash would also illuminate), and agree that side lights being on or off should have nothing to do with the state of relay 209. I'm still going most probably with some weird prior Owner modification, and will be interested in Chris Marsh's response if it was OK and then changed, or if it's just always been this way during his Ownership (just can't see how any single failure in the stock system would cause only the RH rear turn signal lamp to be "on" with the side lights "on").

 

Coincidence?

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Not to hijack this thread, but on a related opposite issue on my 355... I changed all the rear bulbs to LED and installed the Scuding relay for the flashers.

I did notice that things seem to operate normally until I turn the headlights on, then the rear passenger side lens flashes on then shuts off (see first pic). After I step on the brakes, however, the light then comes on and seems to operate normally (second pic). Any idea what might be causing this? Could it be related to the new LED bulbs? Do I need to swap back to normal bulbs to compare/check?

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Other than refitting the standard lamps, I wouldn't really know where to start.

Do the LED lamps have to be fitted a certain way (to ensure the correct polarity?).

The outer lamps have dual functions. Does the turn function work normally (with your foot off the brake)?

 

Thought that might be the case.

Are you sure that they didn't cause it? You might compare the wire colors going to the various bulbs as they are now to the 348 WSM schematic and the 348 schematic that Ian posted to see if things got moved around incorrectly or if something strange (wrongly) got added.

 

This is going to be tough to isolate. In some ways it seems like a short, but in some ways not. Maybe there's a diode in the circuit somewhere messing things up.

Did you try putting on your parking lights (with the console switch) to see if the RH turn light illuminates?
Does the RH rear turn light still illuminate with the flasher relay pulled?

How hard is it to trace the wiring in the tail light cluster (to the 9 pins on the plug). I don't know how the pins are numbered.

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Are all the jumper wires present on the car side of the plug? There should be a black one and red one, according to the wiring diagrams.

Did you check the number plate light as Miro suggested?

 

Of course, check/replace the bulb and, if the bulb then works and if there are only two wires linking the license plate lights to the RH tail lamp, then there should be nothing in this circuit that could be the reason for the RH indicator light coming on when it shouldn't.

 

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Looks like the earth wire is spliced on the back of the lamp assembly and the power wire is spliced somewhere upstream (I think it can be found by following the rectangular side marker wiring). See red circle.

 

Both, Fig. 6 and Fig. 6b Ferrari diagrams I have (I do not have "6a"), as well as your GIF diagram I have (Version 34, 22 Sep 2021), show that both license plate light wires go to the RH tail lamp. Which 348 model/version is your diagram above for?

 

They were based on the USA diagrams posted a few weeks ago. Some were a little blurry, but I have a closeup of the RH tail light here, thanks to @EFerrari34 :

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https://www.ferrarichat.com/forum/posts/149177121/

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Not that Ferrari diagrams ever match reality

 

I guess you mean the upper right red light (rear)?

I would recheck fuse 11 in the passenger footwell. You may have shorted something.

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Spider relay panel shown.

(EDIT: I thought you might have put the K relay in the wrong slot, but that would have affected more lights)

 

Ditto.

With your sidelights off, and RH turn signal on, are any of the other (non-turn) lights illuminated even dimly?

Are all your lights non-LED (including dash turn lights).

If you do continuity checks on the pins of the RH rear tail light cluster connector (with the turn bulb removed), are they all open circuit?

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With the tail light cluster disconnected and the sidelights on, do you get a voltage on the blue wire of the cluster harness connector (car side)? (pin 9 in the wiring diagrams).

 

Did you confirm that all the wiring to the RH taillight assembly, 91b, matches the stock schematic (i.e., no modifications/no additions)?

(If everything looks stock) You could also:

1. Measure the voltage on the L wire of pin 9 in the 91b connector when the turn signal light is wrongly "on" relative to another chassis ground (like the engine block). If +12V that would indicate something upstream is amiss (and the L wire is wrongly getting energized somehow),

and

2. Measure the voltage on the black wires of pin 2 in the 91b connector when the turn signal light is wrongly "on" relative to another chassis ground (like the engine block). Should be 0 volts.

 

Could you identify pin 9 on this photograph for future reference (i.e the blue/turn wire)

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Bottom left? Bottom right? Or none of the above.