help: headlights, windows, wipers, radio out

[yalcin]

Greetings all,

Seeking help with an electrical problem. 1980 Fiat 124 fuel injected automatic. The other day I flicked the headlight switch on, and I abruptly lost the radio, the wipers, the power windows -- and of course, the headlights.

I still have the parking lights (the middle position of the headlight switch), and the car still starts and drives. My signaling lights still work, but at a noticeably diminished speed. I still have "open door" light. The seatbelt light and the break light, which used to temporarily illuminate after starting the car, now remain illuminated as long as the car is on. Looks like the cigarette lighter still works. The hazard light is still illuminated.

So these things must be on independent systems.

I am wondering what the electrical weak link here is, such that it unites the headlights, windows, wipers, and radio, but not the other electrical items.

As potentially relevant background, the car has a new battery. I replaced the alternator with a brand new one from auto recambi last summer. It hasn't been long since I cleaned the grounds.

Perhaps I blew a fuse? The way the electric cut out seemed a bit reminiscent of that. If so, which fuses would make sense to look at, where? I have yet to change a fuse on this car.

On the other hand, I have on occasions in the recent past briefly lost power to windows-wipers-radio-headlights. So that could mean a loose connection. Intuitions about where to look? What could the likely culprit be?

I'm definitely a rookie about all matters electrical but I'm keen to learn and fix the problem. Any suggestions would be greatly welcome. Pointers to other relevant threads also welcome -- I have searched the site, but it's so extensive that I've surely missed some relevant discussions.

Thanks a lot! Seth

[spider2081]

The systems not working are your larger current draw items. This could indicate a battery not fully charged even though it's new. I would check the battery voltage at the alternator output terminal with the engine off and then with the engine running. Off it should be about 12V running about 14 volts.

Next I would inspect the connector for the ignition switch.

Then the brown wire connector under the dash near the hood release

A loose or corroded battery cable connection on the started

The ignition switch itself

Hope this helps

[paintdudeluke]

I won't be something like the battery because it would affect all systems. Unless you have multiple main wires fed to the battery and ONE of them feeding the systems involved is disconnected. This sounds to me like there clearly is a systemic loss involving the systems down. You're thinking that it might be the switch is more along the lines I would be looking for. Somewhere in the system there is a common connection for the involved items. It could be one of the main relays behind the glove box to the left of the ECU. There are multiple major connections routed through the various relays on the panel. I would start there. From what I've seen, most of the switches (for example, headlights) are stand alone serving their respective item rather than being a power junction like on some american systems. I would look a schematic over and see if a relay handles the group of items you mentioned. I have a high index of suspicion that your problem will be found on the relay panel.

EDIT: I looked at the schematic and think you have lost a ground connection. G3 is under the dash above the column. many of the items you mentioned route through there. Plus the other things you mentioned running slow suggest feedback ground loop.

[TX82FIAT]

Check each fuse. Fuses are cheap and can buy at any autopart store. Ground under dash. If it is a fuse the bigger question is why it blew.

[aj81spider]

I've looked quickly at the schematics and the electrical diagnostic manual (both of which I can send you if you don't have them - PM me). It appears that the lights, power window relay, and radio are all powered off the same set of wires. Those wires go through C31 originating at the INT connection of the ignition switch. The power for the lights goes to the light switch and the other two go through C20, so they branch pretty quickly.

I don't think it is a fuze, as the individual items are fuzed after the power splits. It's odd that they went out completely when you turned the lights on. Going out completely would imply that the connection got broken - something that should not be synchronized in time with the switch. Do you know for a fact that they went out when you switched the light on (i.e. the radio was on and it shut off when you flipped the switch), or did you turn the lights on, notice they didn't work, then notice that other things didn't work. That would be the more likely scenario for a broken connection.

In any case - I would start by making sure that you were getting voltage out of the ignition switch first. Disconnect C31 and check there. Bad ignition switches are pretty common. If you are then I would keep moving down the circuit checking voltage until you found the place you stopped getting voltage. At that point the problem should be obvious!

I don't think it is a ground because the left headlight and the right headlight are grounded at different points (the star ground pods on each fender).

[RRoller123]

burned out lighting switch? easy to check.

[yalcin]

Wow as usual, tons of really helpful suggestions -- thanks a lot. Thanks especially to paintdudeluke and aj81spider for actually taking the trouble to check schematics, I really appreciate it. I agree with those who reject the idea that it is a fuse. As per luke's suggestion i inspected the ground pod under the dash. That seemed like a likely culprit, however it is pretty much picture perfect.

aj81spider wrote:

It's odd that they went out completely when you turned the lights on. Going out completely would imply that the connection got broken - something that should not be synchronized in time with the switch. Do you know for a fact that they went out when you switched the light on (i.e. the radio was on and it shut off when you flipped the switch), or did you turn the lights on, notice they didn't work, then notice that other things didn't work. That would be the more likely scenario for a broken connection.

Right. So what happened was: I turned on the car; the radio came on; I flicked the headlight switch on; and the radio then cut out. I then confirmed by testing that the wipers and windows were also out.

Today I got a new piece of information which suggests to me that spider2081 is correct that it is a voltage problem. After driving for a while, the radio returned to life. I attempted to activate the wipers when the radio came back on, but this cut the radio out again. Then, after driving a while, the radio returned again. I believe the voltage issue also would explain why the signal lights are very slow at first, but then gradually pick up speed the longer I drive the car.

I wonder why I would be having this voltage problem with a new alternator and a new battery? I had problems somewhat like this in the past, but they went away when I changed the battery and upgraded the alternator. I thought voltage issues were behind me. I don't understand what could be causing this issue. Maybe I got a bad battery?

spider2081 suggests:

check the battery voltage at the alternator output terminal with the engine off and then with the engine running. Off it should be about 12V running about 14 volts.

So I'll try to do this -- I have a multimeter but I'm just starting, barely know how to use it. But anyway suppose the voltage is lower than it should be, what would the next steps be to correct the problem?

Last thing: RRoller suggested maybe it is a burned out lighting switch. if it were burned out, would the switch still work to activate the parking lights (as it does now)?

thanks again for the great advice --

[AriK]

I had a similar problem that would come and go as it pleased. Light switch turned on, radio turned itself off. Turn signals and tach would become erratic or inop. Took months to track it down, changed radio +feed & neg ground, cleaned up ground pods everywhere under dash and engine comp, no joy. Symptoms less evident when engine was cold. Turns out several months later when i was working on something else i discovered the most obvious and under my nose-- the negative ground wire on on the battery terminal needed tightening, duhhh! Check your terminals, not only terminal to battery but wire to terminal too. Don't only give it only a feel or visual, bring a wrench! Just my 2 cents.

[spider2081]

When checking voltage with a meter, make your measurements with everything connected. Unplugging a connector and checking for voltage is not a good test. It is called "open circuit voltage" and does not check for loose or corroded connections. It seldom shows the cause of an intermittent connection either.
If you are going to unplug something to check voltage use a trouble light.
Current should be flowing in a circuit when you are making your tests. So the items not working should be turned on when you are making your tests even though they are not functioning. It is probably their current draw through a poor connection that is your problem. That current draw will cause a voltage loss across the connection and you will see a lower than desired voltage reading.

Many people like a trouble light over a voltmeter for this reason. The trouble light draws current and will either not light or lights dim in a circuit with a bad connection.

Hope this is some help

[yalcin]

Thanks again spider2081. So I went to O'Reilly and just had them check the battery and the alternator. The battery was fine but low, indicating it was not being fully charged. The guy then checked the alternator at the battery. This involved taking a measurement with the engine off and then with the engine running. The exact result on the computer was the following: "#1545 12V ALTER / VOLT REG FAILED /DIODES PASSED".

So apparently the voltage regulator failed. However, this is puzzling, because the car has a new 95A alternator (with incorporated new regulator) from Auto Ricambi, which I just installed in July. I called the guy at Auto Ricambi, and he was very stand up about it and is going to send me a new voltage regulator straightaway. But he said this is the first time he's heard of this happening, and of course I am surprised also.

I am planning to replace the voltage regulator, but meanwhile I welcome other ideas... is there any way the problem could *not* be the voltage regulator in this scenario? Could it be a faulty/corroded connection at the alternator for example?