Bouncing Ammeter

PAGING jselevan!!!

Could be any of the above, plus could be a bad alternator.

The stock unit doesn't make a ton of amps. My car used to fade pretty badly at idle.

There are several threads here about alternators and the supporting assemblies.

http://ferrarichat.com/forum/search.php?searchid=3867076

Happy hunting.

DM

 

Mine has been bouncing for years, mainly at idle. I have not had any problems.

 

Hello SCantera,

My amp meter needle has been bouncing ever since I bought the car (10 years). I did change the regulator to an electronic one and had the alternator rebuilt but it has not cured the problem. Maybe the amp meter itself is the problem?

 

A loose connection?

 

Yes, I had the car at HHI for the Saturday "Car Club Day" in '07. I have not been back with the car since then (mainly because they've been requiring people to be there by 7:00 or 7:30 AM, and it's a 2+ hour drive from Charleston).

 

Most likely, as more often than not, this "issue" is caused by loose or oxidized ground connection somewhere in the circuit.
And this "issue" of "bouncing ammeter needle" is probably more common in vintage cars with alternators than most realize.
Just like everything else in cars, electrical systems require periodical thorough maintenance also.
Timo

 

Contact problems/high resistance of the ammeter terminals is a serious problem, it can lead to burned/melted wires or even a fire behind your dashboard due to the high current in the ammeter wiring.
You might want to check the crimped connectors on the two red wires going to the ammeter and clean them using contact cleaner (Kontakt 60), or replace them. Disconnect your battery first.

As a test, when you bridge the ammeter by connecting both red wires which were connected to the ammeter, to each other using a temporary wire with spade connectors (take care to isolate the temporary wiring well), do you still have the lights dimming/brightening effect? If so, your regulator most probably needs an overhaul or you exchange it against an electronic one, such as HUECO 130216 (14V) or 130217 (14.8V).
If the lights are ok now, clean both the connectors on the wires and ammeter, if this did not fix the problem, have the ammeter checked or exchange against a voltmeter (which is what i did).

 

Adrian has it right.

First, it does not sound like an amp meter. The amp meter is simply a heavy gauge coil of wire creating a magnetic field. It the leads on the amp meter are loose, the contact resistance can vary with road bumps, and this might create your symptom. However, if the dimming of the lights and the frequency of the amp meter oscillation is steady, and not related to road bumps, then it is unlikely a mechanical issue. Nonetheless, with the lights on for a few minutes, reach behind and touch the leads or the case of the amp meter. It should not be hot, but warm. If it is hot, you should quickly tighten up the small nuts that hold the ring connectors to the post. This is a real problem and can cause a fire if these leads are not snug on the amp meter. To do this, please, please disconnect the battery first. Taking the leads off of the alternator to abrade them with sand paper is a good idea, and abrade the nuts at the same time. This also provides an opportunity to short the two amp meter leads together (as suggested by Adrian) to eliminate the amp meter from the circuit. Take a short 6 mm screw and nut, tighten them together, and then wrap them with electrical tape to insulate from everything. Then drive the car to see what happens. I do not think it will make a difference, but it is a good idea to refresh the brass nuts and ring contacts by sanding them. This lowers contact resistance at the amp meter, which is the point of greatest current flow in the car (other than the battery).

If you have a steady oscillation of the amp meter and a steady dimming of the lights, it is more likely a regulator or alternator issue. If you chassis is an early number, you may have a mechanical regulator. These can oscillate as they are referred to as a "bang-bang" feedback control system. Later models, with the red box under the dash, are electronic units and should not lead to this symptom. They will simply fail.

If you have oil on the carbon brushes of the alternator, they can go through periods (milliseconds or seconds) of poor contact, and this can produce your symptom.

A loose ground is unlikely. While grounding problems are common in these cars, one that changes resistance periodically would be unusual.

Please tell us more, that is, the chassis number or model year, the frequency of the dimming or is purely related to bumps, etc.

Jim S.

 

Unless it was a U.S. thing, I suspect that 5216 has the red box (regulator) under the instrument panel. 3002 and 2900 both have the red box.

Jim S.

 

I have found NOS Marelli alternators with built in voltage regulator for $250 that are easy to install and nearly plug-'n-play. You must make a pigtail to short to bypass the voltage reg input to output so the 12V is used as an alternator exciter circuuit (really easy to do).
PM me if interested.

Scott

 

Mine bounce at idle and bounce less when the rpm's increase. I just replaced an alternator on one car and it still bounces. However, it does bounce in a more positive direction. I suspect the bouncing is more from age and corrosion.

Did anyone have this same issue back in the day or did it stay steady and gradually begin to bounce?

 

Never really noticed it bouncing, but it did react to everything that was going on, wipers, blinkers, brake light, just about anything that effected current flow would cause it it move. Actually, a quick flick to the left and then back to the plus side
So I guess, stop and go traffic on a rainy night might keep it very busy.

 

A separate voltage regulator is news to me-- I thought they all had the alternator and VR in one unit.
I looked at the wiring diagram and didn't see it either, but maybe I didn't know what to look for.

My car 2840 is a Euro and I'll look under the dash for this mysterious red box-- might save me having to R+R the alternator. (Ammeters shows poor charging, which worsens w turning on headlights, etc.)

Jim

 

I don't see any red (or any other color) box under the dash-- just a lot of wires and the emergency flasher clicker that was added when the car was imported from Italy in 1976.

Anywhere else I should look?

Unfortunately, I covered the firewall with black foam noise and heat insulation sheet material so seeing what's on there is not so easy. :-(

Jim

 

I see from my English translation of the factory repair manual that I am looking for a box with white, black, and green wires going to it.

But where is it?
I do not see anything like that below the fuse boxes in the front trunk area.

Jim

 

My first Dino, 02832, had the regulator on the relay/fuse board in the front spare tire compartment. It is a black, large box. The later cars 2900 and 3002, have the red box under the instrument cluster, to the right of the ignition switch. I do not believe any of the Dinos had a alternator with built in regulator, but later cars may have ( I do not have experience with later cars).

Jim S.

 

Jim,

Do you see it here?
The second pic is a closeup of the connector to the silver box on the lower left of the cluster.

The black box in the lower right is marked FIAMM, so I presume this is the air horn relay.

None of the boxes have 3 wires of the right colors on them

Thank you,

Jim
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There were several different regulators installed, depending on the series, year and what was available in stock.

The metal box on the left is the regulator in your setup, you can see the two regulator terminals '15' (control voltage, coming from the ignition key via fuse 12) and '67' (regulation output, going to the Alternator field input terminal via 8A fuse on the firewall), as well as ground.
Your wiring looks correct, the white wire is connected to 67 and the red wire to 15.

If broken, a good replacement is a Hueco 13 0723 electronic regulator.

Happy Holidays,
Adrian

 

Adrian - This may well be the regulator. The terminals labeled 15 and 67 are correct numbers according to my schematic. There must be a ground, which I assume is a ring connector to one of the fasteners electrically in contact with the metal "box." Please check to see whether you can identify where the ground makes contact with the device. If you find the ground, then at least we know there are three wires going to this device. My color code calls for a green and white wire. I see a red wire. Can you discern the color of the wire on terminal 67?

Finally, to confirm that this is the regulator, there should be a fused breaker supplying the plus supply to the regulator. Trace the two visible wires connecting to the device and see if one of them leads to a fuse above, and it should be labeled regulator.

If these steps confirm that this is the regulator, then a voltmeter applied to the wires can help identify whether it is working. Before I explain how to do this, please confirm the presence of the regulator.

Others may be able to identify this as the regulator without all this investigation. I do not have an early car to compare. As stated, mine is under the instrument cluster to the right of the ignition switch.

Jim S.

 

The silver box is it and it does have 3 wires, the third one being the ground wire attached to the mounting screw.

Here's what's inside the unit and how I diagnosed mine, Corbani give a few comments on why there might be flicker
http://www.ferrarichat.com/forum/showthread.php?t=193757