Battery dash light + voltage

[rreegg]

Couple months ago the battery light on the dash was on momentarily then went off - seemed like a blip because the after market voltage gauge seemed to be above 13.5V.

Now today I’m seeing the dash battery light come on/off again. While parked with the battery light on I can Rev the engine and the voltage gauge does not change. Then the light will turn off and While parked I can rev the engine and the voltage gauge goes up

I measured the volts of the batteries and they are both about 13.1V.

Any idea what the issue might be here? I’m not sure what conditions make the dash battery light turn on.
Am thinking possible connection/wiring issues.
Alternator has the date 2013 on it replaced by a PO.
Truck has aftermarket equus voltage gauge.

Normally when driving the voltage gauge will be around 13.8V

Gonna drive the truck for the day and monitor things

 

[Kdo58]

I have aftermarket gauge, I just pulled the bulb out.

 

[DougBoy66]

It looks like your oem guage thinks your battery has zero volts. Maybe a dash wire/sending wire.

 

[rreegg]

The concerning thing is when the dash battery light is On the aftermarket gauge will be “stuck” at 12v and not jump up when given throttle. Just want to make sure the alternator isn’t slowly givin out.

So whatever the issue is it has shared behavior between dash cluster and aftermarket gauges

When driving to work the above condition (battery dash light on and no aftermarket gauge response) would occur intermittently.

 

[DougBoy66]

Is the voltage regulator internal on the alternator or external?

 

[rreegg]

@DougBoy66 not sure, is this external?

 

[IDIBRONCO]

That's a 1G alternator. It has an external regulator. It's mounted on the passenger's side inner fender. It's basically square. It had a wide, flat plug with four wires, I believe, going into it.

 

[DougBoy66]

Gonna look something like this

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[DougBoy66]

I think your best bet is to have your alternator tested and if it is working correctly I would guess the voltage regulator is giving up. If I recall correctly sometimes when they are failing they will work sporadically but eventually fail all together.

 

[DougBoy66]

Oriellys has this one. More money though

You must be registered for see images attach

 

[rreegg]

Dash battery light and static 12v on gauge happened both in morning and afternoon driving. It’ll flip flop between on and off for about a minute or two on either side - then stay off when the coolant temp is above ~180

Will test alternator

 

[DougBoy66]

Sounds like a plan, Hope ya find the issue.

 

[rreegg]

Scanner at the auto part store said the voltage reg was bad so just replaced it. Thanks all for the help

 

[DirtyWood]

I've also had the battery light come on/off due to poor grounding on the voltage regulator, but it sounds like you're good to go now.