High beams not working

Probably a switch issue. It turns the low beams off but not the high beams on. You should go to the high beam relay and see it is getting a signal to switch. I bet not.

 

I have left side high beam not working. There is no voltage going to the plug measured after disconnected from the bulb. Right side head beam and both low beams are working fine. Before I changed the relay for high beams, I had no high beams at all. In other words, the new relay restored right side only. I suspect the high beams circuit had issue causing the relay to fail. Anyone had similar experience tracing this problem. The headlight wire harness seems in very good shape.
Btw, both of my doors have no light (one red shining to the back and one shining to the ground). No sure it is a related issue. Please kindly help.

 

Did you change the day and night flasher relay "P"?

 

You may want to create a new message thread for your problem, jcbam, otherwise, it may get confusing for readers. Also, please fill out your profile details, so we know what car you have M, GT, GTA, etc? Did you know there is a fuse in the passenger footwell specifically for the left high beam headlight?

 

Along 495, with your low beam headlights on, if you use your headlight flasher, do the high beams come on? Continuous high beam and high beam flash use a different set of electrical contacts on your steering column.

 

Thanks. I will create another thread. I have M GTA. Let me look for the light high beam fuse.

 

Sounds like bad ground somewhere.

 

So it's probably not a stalk problem.

When you turn on the low beam headlights, it activates two relays. One relay is for low beam power, the other relay is relay "P". Relay "P" disables the daytime flashers in the front grille and diverts the steering column high beam switch signals (when used) to the high beam headlight relays. Although my 456 wiring diagrams suggest that a broken "P" relay would only affect the high beams and daytime flashers, I would still replace/exchange it for faultfinding purposes. I recall there was a special circuit on cars of this era in the USA only, which affected both low and high beams (due to USA vehicle laws). On the Ferrari 550, I believe this legal requirement was achieved with a different type of relay, but, oddly, on the Ferrari 456, the "P" relays for all versions/regions seems to be the same.

 

Just reading the 550 workshop manual (to refresh my memory). In the USA, when the high beam headlights are selected, both low and high beam lights illuminate. Elsewhere, the low beams are de-activated. Only the high beams operate. Perhaps a USA 456 owner can confirm that the 456 is the same as the 550?

 

Get a professional automotive electrician to do it. Easiest way. But not the most inexpencive one. But very sad if something breaks when doing things yourself. Or you could test a light stalk off of another car that you know works.

 

The high beams use the same grounds as the low beams, the side markers, the windscreen wiper, the horn compressor, the turn indicators and the headlight lifting motors.

There are two grounds/earths, one for the left side and one for the right side. Do grounds on both sides fail at the same time?

It doesn't sound like a grounding problem to me.

 

But if you really want to check the grounds, here they are:

Image Unavailable, Please Login

The only other grounds in this system are the relay grounds. Dozens of things wouldn't work if they were faulty.

 

Even a professional automotive electrician will have difficulties with this circuit if he/she is A) not familiar with the 456 or B) he doesn't have a wiring diagram. Only Ferrari technicians would have access to wiring diagrams. Either that, or your local automotive electrician has seen my diagram on the forum :

Ferrari 456M Lighting Wiring Diagram (USA)

You don't need to pull the car to pieces to check the stalk. You can check the circuits very easily with a cheap digital voltmeter at the relay panel. I can provide step by step instructions, if required, without pulling the car to pieces (i.e. other than removing relays).

You can:

Check that the output of the steering column high beam switches are getting to the relay panel (e.g. contact #30 of flasher relay P's socket should have 12volts when using the high beam).
Check that there is continuity between the flasher relay and the high beam relay (i.e. a specific part of the relay panel internal wiring). As you probably already know, these panels have a tendency of frying themselves. You can also check the output of relay "P" at relay "M" (socket) contact 86 (after reinstalling relay P)
Check the output of the high beam relays (either at the fuses or at relay panel output plug "A").

Note that if your high beam indicator light is (also) not working on your instrument panel, the problem will probably be in your relay panel (or upstream of that). The indicator light is on the output of the left high beam fuse.

Rechecking my wiring diagram, I see that it already incorporates the USA variation of having both the low and high beam operate when on high beam.

 

So, in summary:

Pull back stalk with headlights on low beam:
High beams go out, low stay on.
Push stalk forward with headlights on low beam:
Both high and low go out.


Strange. In the second case, do your marker lights also extinguish or dim? If so, it sounds like you have some kind of short in the column switch. Either that or there is something missing in the wiring diagrams.

Image Unavailable, Please Login

If you look at the steering column wiring diagram above, when you put your lights from OFF to LOw beam, (+) ignition power on pin 2 of plug D goes to the (muddy) yellow wire in the diagram (not the real colour on the car). This activates the low beams and puts power at the bottom of the funny looking dogleg high beam switch. When you push the stalk forward (to the left in the diagram), this power goes to pin 1 of plug D, but also to pin 4 of plug A. Pin 4 is not used on the 550. It is used on the Ferrari 355.

Does your dashboard high beam indicator light not illuminate when you push or pull the high beam stalk?

Thanks for the additional information. At least we can confirm that the defect is in the relay panel or upstream of that. Unfortunately (unless the diagrams are incorrect), the symptoms are pointing towards the column $talk. When you put your ear close to the column switch can you hear any arcing when you push the switch?

 

P.S. Please note that I changed my diagnosis when you changed your information

 

My apologies, folks. I have a bad habit of getting my 456's and 550's mixed up.

On the 550:

The dashboard indicator light is on the output of the left high beam fuse. This means the dashboard indicator light should illuminate if you pull or push your high beam (stalk) light switch.

On the 456M:

The dashboard light is directly driven by the steering column high beam push switch via plug A pin 4. With low beams on, the high beam flasher function (according to the 456 diagrams) should not illuminate the dashboard high beam indicator light. Maybe someone with a good car can confirm this?

This is definitely pointing towards a column switch problem. Rifledriver seems to have got it right in post #2 . I went the long way around.

 

Any idea which relay it was?

 

Interesting. That was my first thought, but the later symptoms seemed to be pointing away from that. There may be a fault with my wiring diagram.

Anway, thanks for the update. Good to hear it was fixed.