Voltage regulator wireing

[JohnnyB]

Hey Guys, how are u doing?

I got a little Problem with temperature gauge and my wireing as it seems and i hope that u can give me some hint...
My temperature gauge is always circa 20°C above the value that i measre with my IR thermometer. A few month ago i got the same Problem and thought it was the voltage regulator, that was not regulating any longer. I replaced it and the gauge was fine.

Now i got the same issue again. And again it seems that the electrical regulator that i have now seems to be defect.
I ordered a new mechanical one yesterday. Today morning, i was checking the wireing diagramm and compared it to my wireing.
In the diagramm there are two wires , one (grey) from Pin 677 to the alternator and one (orange) from Pin 15 to fuse L.

In my car, the grey one is fitted correct, but instead a orange one from pin 15 to the fuse box, i got a wire from pin 15 to my
ignition coil. The orange one which i think would be the corret one is connected to a capacitor next to the ignition coil, which i cant find in the wireing diagramm.

Can anyone tell me, what this capacitor is for? May this be the Problem, my regulators were dying?
I guess i can prove the orange one to be the correct one, if i fit it to the regulator and hope i see the charge indicator light, which was never working in my car^^

Thx in advance

Car: 74 Fiat 124 CC1 1800

[aj81spider]

I'm not sure what's going on with your voltage regulator. I think you are correct that the wiring has been modified (I have a 1974 as well, and it matched the wiring diagram until I put in the 95 amp alternator). I'd map out the circuits and create a diagram before changing things. The previous owner was trying to do something and there's no telling what might break if you just disconnect it.

However, fixing the voltage regulator will not do anything for your charging light. That light goes to a relay. The relay is normally closed and completes a circuit when the alternator is not running (the light is lit when the alternator is not running). When the alternator starts up it energized the relay, opening it up and making the light go off. The voltage regulator is not involved in this at all.

[DieselSpider]

The capacitor mounted on the ignition coil is a high pass filter to reduce ignition noise interfering with radio reception. It can also help protect other electronics in the car from spike damage. If solid state voltage regulators are failing regularly there is a potential that the capacitor may need replacing.

[spider2081]

The orange one which i think would be the corret one is connected to a capacitor next to the ignition coil,

Many Fiat cars in the vintage of ignition points use a ballast resistor in series with the ignition coil circuit. In many US made cars the ballast resistor is placed before the coil in the wire from the ignition switch. In some non US manufactured cars like Fiat the ballast resistor is wired between the ignition points and the coil. The ballast resistor Fiat used is a red rectangular shaped device about 3/8 inch thick. Is this possibly what you have mounted near your coil?? Neither a ballast resistor or filter capacitor are shown in the 1974 wire diagram I am looking at but I believe the 74 cars were factory delivered with dual ignition points. This make me curious if there might be a error in the wire diagram, as searching for a coil, on line parts suppliers show only one coil from 1966-1978. Other wire diagrams show the ballast resistor.

[JohnnyB]

Hey guys, first of all thank u very much for ur fast responses.

With my new regulator, the voltage seems to better (up to 14.9 V instead of above 16...) I installed it the way it was in my car as well as the way the wireing diagramm says. Couldnt see any differences.

The orange one which i think would be the corret one is connected to a capacitor next to the ignition coil,

Many Fiat cars in the vintage of ignition points use a ballast resistor in series with the ignition coil circuit. In many US made cars the ballast resistor is placed before the coil in the wire from the ignition switch. In some non US manufactured cars like Fiat the ballast resistor is wired between the ignition points and the coil. The ballast resistor Fiat used is a red rectangular shaped device about 3/8 inch thick. Is this possibly what you have mounted near your coil?? Neither a ballast resistor or filter capacitor are shown in the 1974 wire diagram I am looking at but I believe the 74 cars were factory delivered with dual ignition points. This make me curious if there might be a error in the wire diagram, as searching for a coil, on line parts suppliers show only one coil from 1966-1978. Other wire diagrams show the ballast resistor.

I got that resistor, i can find it in my car, aswell as in the diagram right at the coil. The thing i descibed first is definitely a capacitor. It got 2 connections, one open and one to the orange wire. It got an inscription with "2,2 µF", so i think the statement "DieselSpider" might be correct.

Nevertheless my temperature gauge stays with switched on fan at ca. 105-110°C . Next step would be changing the thermostat and cleaning up all connections.
But im still not convinced weather the temperature is really to high, or if the gauges value is just wrong. When i measure with IR gun, the values at the T are around 85° and 89° at upper cooler. But im not sure how the different surfaces tramsport the heat.
Directly on the Cylinderhead right to the temperature sensors, i measure around 100-110 °C.
Are these normal values?

From my understanding it should be quite normal that the metal is hotter than the running coolant water , or am i wrong? Does anyone got some experience values from the cylinder head.

Thanks in advance

[spider2081]

A friend was showing me a 1972 124 coupe Wednesday. He had a wire diagram that he copied from his owners manual. The wire diagram shower a ballast resistor but there wasn't one in the car. His car has a single set of points and he thinks the coil is original. Maybe there are 2 coils available for the Fiats. Yes Dieselspider sounds correct in its a filter cap for the radio.
I think a few people have posted that their fan comes on around 105-110C when their system has air in it. In addition the over temp switch (also located in the head between spark plugs) and a poor ground on the coolant temperature gauge in the dash can also cause the gauge to indicate higher than the actual temperature.