Technical ignition lights stays on

[plasticpig1972]

When i start my Giardiniera and rev it up the Ignition/charging light stays on.
So i looked at the Voltage Regulator and the contacts on the right coil were burnt.
I have fitted a new Electronic Voltage Regulator from Ricambi and it's still the same problem. I have looked at the Brushes in the Generator/Dynamo have they are only half worn (still in good condition).
I measured Volts from Generator terminals at Tickover and it's 7 Volts.
Do i need to test at high Revs and how many Volts should i have.
Thanks in advance Boys
Alan

 

[F123C]

There's a free to download copy of the official Fiat workshop manual available in the Downloads section (blue band at the top of the page). Click on this, select 500 (Classic) and click on Fiat 500 Classic workshop manual.

If you then go to Page 112, 2nd paragraph, you'll find the official method of checking voltage output of the generator.
In summary it seems to say to disconnect the 2 wires from the generator (for safety I think these 2 disconnected wire terminals should then be covered with insulation), join the 2 generator terminals with a wire, connect a voltmeter between these 2 now joined terminals and earth, run the engine at a maximum of 1000 rpm and you should get up to 20 volts if the generator is ok.

In general, the ignition/charging light goes out when the generator output voltage exceeds the battery voltage, clearly 7 volts output isn't going to achieve this. On the 500, this light is connected between earth and terminal 51 on the voltage regulator (iirc it's a small green wire?).

Further on in the above workshop manual section, there's instructions for checking/adjusting the voltage regulator but I don't know how much of this info is applicable to the new electronic voltage regulator you've now fitted.

Any idea on why the original voltage regulator 3rd coil contacts became damaged (this is the cut-out relay which disconnects the generator from the battery if generator output drops too low - prevents the battery trying to discharge back through the generator to earth). Maybe some damage was done to your generator? There's comprehensive instructions in the above manual on checking each part of the generator should you need them.

Additionally, in the same Downloads section, there is also available a copy of the Fiat 500F/L Users Manual - this includes a wiring diagram on page 34/35.

Hth,

Al.

 

[plasticpig1972]

Many thanks
Alan

 

[plasticpig1972]

I will remove the brown wire from terminal 51 and also the black wire from terminal 67. These are from the Generator and put them together. Connect voltmeter from them to earth/engine when running to measure volts at fast tickover 1,000rpms. I should get minimum 15 volts.
If ok then the problem is the green wire feeding the ignition warning light on the dashboard.
Alan

 

[F123C]

I will remove the brown wire from terminal 51 and also the black wire from terminal 67. These are from the Generator and put them together. Connect voltmeter from them to earth/engine when running to measure volts at fast tickover 1,000rpms. I should get minimum 15 volts.
If ok then the problem is the green wire feeding the ignition warning light on the dashboard.
Alan

Do NOT connect the wires from the generator together (i.e. the above brown and black wires). Just disconnect them from the generator and cover their ends with electrical tape or similar.

I may not have made it clear, so to clarify, having disconnected these 2 wires, you then bridge the 2 terminals on the generator with a piece of wire and connect a voltmeter between this bridge wire and earth to check the generator maximum output.
[Essentially what you're doing is feeding maximum (i.e. unregulated) power to the field windings from the output terminal to check the maximum output of the generator - the initial charging output to 'get things going' comes from residual magnetism within the generator.]

As you say, you should see 15 volts (some say 13.5v minimum) if the generator is ok. The workshop manual warns against running the engine faster than 1000 rpm if the output is too low, also ensure that the voltage isn't allowed to exceed 20 volts.

Re:- the charge warning light. I got it wrong in my post#2 above - the charge warning light is not connected between terminal 67 on the regulator and EARTH... The warning light green wire I mentioned is connected to terminal 67 on the voltage regulator. This green wire goes to one side of the charge warning light in the speedometer, the other side of the light is connected to battery voltage (not earth!) - it's a sort of balancing act, as the generator voltage comes up towards battery voltage, the light dims and then goes out as generator voltage equals or exceeds battery voltage. If you check out the wiring diagram in the Owner's Manual, you'll see what I mean.

Also, given that the charge warning light is on, means that there is nothing wrong with the w/light (item no. 18 in the wiring diagram) in the speedometer, nor it's wiring and it isn't, iirc, fused - if it fails to go off as the engine speed is increased, it points to either the generator output is too low or the regulator is faulty.

I note you've already replaced the voltage with an electronic version.
I try to avoid using electronic stuff, they're very unforgiving if you make a mistake e.g. accidentally short something out, connect something incorrectly or while there's still another uncorrected fault in the circuit.
Of course you won't usually know if you've damaged the new unit so will assume it has to be ok since it's new and thus spend a lot of time looking for a fault elsewhere in the circuit.
I'm not saying you have actually damaged the new voltage regulator, just bear this possibility in mind if you can't find another obvious fault e.g. faulty brushes or other generator fault.

Re:- Brush wear? You mentioned the brushes seemed ok and were maybe 1/2 worn. Sometimes when the brushes wear down, the springs which push them against the commutator make contact with the metal brush holders, preventing them from pressing the brushes any further. This results in arcing, possible damage to the commutator and low or poor generator output.
Back when I worked on dynamo-type generators (40 or so years ago :chin: ), the most common problem, by far, was brush wear.
Iirc, Fiat used to recommend that these brushes were inspected and changed if necessary at c. 30,000 mile intervals to avoid problems.

Hth,

Al.

 

[plasticpig1972]

ok i've removed Cowling.
I removed the Black/White cable.
removed Brown cable.
I've put a Bridge across the Terminals on the Generator.
Now i need to start the Engine and measure with Tester Volts between Bridge and Body of Generator. On fast tickover is that right.
Cheers
Alan

 

[plasticpig1972]

Just run the engine on fast tickover and i get 11 Volts.
Connected back to Terminals and started car.
If i rev up the engine the Ignition Light flickers and dims but will not go out completly so i imagine the output of the Generator is not enough.
Maybe i need to strip generator and change Brushes and also clean comutator etc.
Alan

 

[F123C]

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Maybe i need to strip generator and change Brushes and also clean comutator etc.
Alan

Hi Alan,

Yes, I think this would be the next step.

While you have the generator apart, you might also check the commutator and field windings, if you have an ohm meter.

The workshop manual (available f.o.c. in the Downloads section in the blue band at the top of this page), describes how to do these tests (pages 112-114) and also how to check out everything else in the generator - read this carefully, there's some very useful info/tips here, especially on how to bed new brushes to the commutator and the easy way to refit the end plate complete with the brushes to the generator body.

Given you were getting 11 volts, I'd be hopeful that a commutator clean and fitting new brushes (as you surmise) should restore your generator output to normal.

Al.

 

[plasticpig1972]

Hi Al,
well i've removed the Generator/Dynamo and cleaned /polished Commutator. Fitted new Brushes. I saw the Communtator is a little worn the width of the old Brushes so i put a very small chamfer on the ends of the new Brushes. To be sure they run in the centre of the worn part and have good contact. The ideal would have been to give the Commutator a very light skim but i don't have a Lathe. The old Brushes had worn down by approx 4 to 5mm so with the new Brushes the springs will put more pressure.
All back together and ready for a test run soon.
cheers
Alan

 

[plasticpig1972]

Many thanks
for all the help my Giardiniera is now charging and running well.
For info i fitted new Brushes Generator and new Electronic Voltage Control.
Cheers
Alan