Front/Rear Lights,Brake Lights, and Horn Stopped Working

[Nasukau]

Hi All,
I came back from a drive last week and all lights were working and the horn. Went to drive today and I have no front or rear lights. No brake lights. No horn and no running lights. But the car starts and runs just fine. Inside dash and dome light do work. I’m confused on what’s happening and where to actually start troubleshooting. Electrical is the worst for me even though this is a simple wire harness. May I get some advice on where to start to troubleshoot.

Thank you,
Denny

[SonicRaT]

You'll want to check the yellow with black wire coming from the terminal box to the generator cut-out, and then the yellow wires coming from the generator cut-out to the horn / light switch.

[Mike Peters]

the power source for your horn and lights originates at the generator cutout and runs to the light switch at the base of the steering column. Did this wire come loose from the cutout? In not, then check to see if there is power to the light switch.

[Nasukau]

I am running an alternator. Should i have 6v at my alternator with the key on/off?

Denny

[SonicRaT]

With an alternator typically the yellow wires are all connected together on the single alternator post. You should be able to get 6V there at all times in most configurations. I've found a handy resource for the wiring is this PDF:

https://www.mafca.com/downloads/Semi...ex%20Janke.pdf

[Nasukau]

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I have no voltage at my alternator. I have 6v at the terminal post on drivers side.

Denny

[Doug Linden]

Your ammeter could be open circuit. Try putting a jumper across the two junction box terminals to verify that.

[Nasukau]

I put the jumper wire on and now all the lights and horn are working. So i have a bad ammeter that needs to be changed out?

Denny

[Herb Concord Ca]

Sure sounds like it.

[Brentwood Bob]

30 amp meter?

[Badpuppy]

Originally Posted by Brentwood Bob

30 amp meter?

20A is all that's needed.

Battery needs only a couple amps to charge. Discharge to full lights and coil load about 16A.

[Patrick L.]

I'r recommend trying to find an original ammeter.

[katy]

In post #4 he says the car has an alternator, it may need a shunt to go w/a 20 amp ammeter.

[Nasukau]

I am running a 20 amp ammeter. It has worked for the last four years with no issues.

Denny

[rotorwrench]

The alternators (one wire) are connected to the battery through the amp meter. There should be voltage at the large alternator terminal all the time unless there is a battery cut off switch. The alternator has a diode bridge inside to keep power from feeding back through it. The horn and light switch are also connected at the alternator terminal so they are connected to power all the time.

[Nasukau]

Thanks everyone. I will switch out my ammeter and see if this fixes my issue.

Denny