Odd electrical behavior (1 Viewer)

[Godwin]

For a few months I've noticed unusual charging, or discharging, activity with my 60's electrical system. What occurs is that at idle up to ca. 1500 the brake and charge lights will pulse brightly on and off at ca. 1 second interval. As rpm are increased the the pulse rate remains but the dash lights become dimmer until no longer lit. This behavior is not consistent. When the Cruiser is cool, as in early morning, the lights may not pulse, but when hot the lights are more likely to pulse. The brake and charge lights will go out when the brake lights or headlights are on.

The alternator is delivering good voltage, on-dash Autometer gauge reads ca. 14 v, but I do notice a slight, almost imperceptible, pulsing of voltage I have swapped out two alternators and three VR and these symptoms remain. I also swapped out the charge light relay to no effect. I don't think this is a grounding issue as I've installed extra ground wires.

Any ideas? This is driving me crazy.

 

[Output Shaft]

Weird..

There could be a long flow chart of trying this, then that, but the first thing to rule out definitively is the alt & Reg. Unplug the alt from the battery completely and start the engine and run it without the alt. See if that changes it.

The fact that the brake light and charge light problem goes away when the headlights or brakes are on, is pointing to a bad grounding junction. Floating ground.
If the alt is ruled out as good after testing the engine with it disconnected, personally I would check that grounding junction plug thingy behind the gauge cluster, tucked in behind the wiring harness to make sure it isn't burnt.

 

[dkyuss]

don't think this is a grounding issue as I've installed extra ground wires.

Im still getting familiar with these cruisers, but in industrial machines, grounding is very specific and can cause weird issues if ground loops are introduced by adding ground wires without reason. These are 'loops' in the grounding system so that current, which will take the path of least resistance has the potential to split and travel multiple paths back to the neg terminal of the battery. Ground loops also create large EMF levels which are not good for the body long term close proximity exposure..... I have now fixed multiple 'electrical gremlins' on industrial machinery by correcting ground loops and the electrical 'noise' they create.

Generally speaking you want to have every ground wire go to one point and only that point (generally neg terminal of battery). If you have wires interconnecting frame, engine and body etc, these will produce loops as current will travel through bolt connection and wires etc all at once. You would want one wire from frame to battery, another from body to battery another from engine to battery etc etc... Hope that makes sense.

With that being said, I can not think of why it would cause the issues you are describing but you never know , but something to watch out for and correct if 'created'.

 

[doug720]

As said above, sounds like a ground problem to me. So many odd light issues are bad grounds. Check all points listed by OS and dykuss.

I believe you cant have too many grounds on a vehicle. I ground the body, frame engine, instrument cluster, in at least 2 places each, and use heavy ground cables, same size as positive battery cables back to the battery.

 

[sfd60]

Weird..

There could be a long flow chart of trying this, then that, but the first thing to rule out definitively is the alt & Reg. Unplug the alt from the battery completely and start the engine and run it without the alt. See if that changes it.

The fact that the brake light and charge light problem goes away when the headlights or brakes are on, is pointing to a bad grounding junction. Floating ground.
If the alt is ruled out as good after testing the engine with it disconnected, personally I would check that grounding junction plug thingy behind the gauge cluster, tucked in behind the wiring harness to make sure it isn't burnt.

View attachment 1275585

did you find out what casued that?

 

[Output Shaft]

did you find out what casued that?

That picture is of someone else's ground connector. They usually get like that from using higher wattage headlamps without upgrading the headlight wiring harness.

 

[sfd60]

mine did that also but didnt change out headlights just upgraded radio

 

[Godwin]

A couple of additional electrical observations that may or may not have any connection to the odd pulsing of the charge and brake lights.

About 9 months ago the I had a VR go into an overcharging state in which it was intermittently producing 16+v for periods of 15-30 sec. I had to drive the Cruiser for ca. an hour under this condition before I could swap out the alternator.

Today my brake switch failed in a constantly on condition. I had to disconnect the switch to shut off the lights and in doing so discovered some PO wiring hack into the brake light switch wiring. Also the metal tube of the steering column under the dash gets rather hot.

I'll be swapping out the brake switch in a day or two and will then see if the electrical problem was with the switch.