1977 K10 generator light quit working not exciting alternator

[blackbird454]

also-- check your light bulb in dash for gen/alt- If that light bulb is burnt out it could also be the issue. Like Ricko1966 pointed out- 12v source through light bulb to terminal on alt -which acts as ground- Light comes on. Once alternator starts alternator feeds 12v back up the wire (Think of garden hose with water being fed into both ends- the water doesn't flow)- so since the light bulb is being fed 12v from both directions it will not light up (electricity not flowing)

Edited - @blackbird454 ,you posted when I was typing- Yes, you got it....

Gotcha yeah I was confused since my light has a positive and a ground but I understand 12v to red wire black wire to terminal on alt I got this truck for my sons first vehicle so I’m chasing down all the gremlins trying to make her a decent rig for him

 

[blackbird454]

also-- check your light bulb in dash for gen/alt- If that light bulb is burnt out it could also be the issue. Like Ricko1966 pointed out- 12v source through light bulb to terminal on alt -which acts as ground- Light comes on. Once alternator starts alternator feeds 12v back up the wire (Think of garden hose with water being fed into both ends- the water doesn't flow)- so since the light bulb is being fed 12v from both directions it will not light up (electricity not flowing)

Edited - @blackbird454 ,you posted when I was typing- Yes, you got it....

For some reason I can get the gen light to work even using the oil pressure dummy light still nothing (it works) every time I assume it’s the printed circuit board or wiring

 

[blackbird454]

also-- check your light bulb in dash for gen/alt- If that light bulb is burnt out it could also be the issue. Like Ricko1966 pointed out- 12v source through light bulb to terminal on alt -which acts as ground- Light comes on. Once alternator starts alternator feeds 12v back up the wire (Think of garden hose with water being fed into both ends- the water doesn't flow)- so since the light bulb is being fed 12v from both directions it will not light up (electricity not flowing)

Edited - @blackbird454 ,you posted when I was typing- Yes, you got it....

So I tried this setup yesterday with the gauge light I posted earlier it did not work as mentioned hooking 12v to the positive bulb side and the ground to terminal one did nothing hooking 12v to the light then another 12v wire to terminal 1 worked but the light stays lit

 

[Ricko1966]

So I tried this setup yesterday with the gauge light I posted earlier it did not work as mentioned hooking 12v to the positive bulb side and the ground to terminal one did nothing hooking 12v to the light then another 12v wire to terminal 1 worked but the light stays lit

What???!!!

 

[Ricko1966]

If you wire it just like the picture in post 11 with a plain old 12v bulb, no gauge, nothing else,no led,just 1 plain old 12v bulb switched power to it other side of light to terminal 1. If you wire it just like the pic in post 11 if the alternator is good the light will light when you turn the key and go off when the alternator starts charging. GUARANTEED!!!! You do have terminal 2 connected as before,correct?

 

[Ricko1966]

You must be registered for see images attach

 

[blackbird454]

If you wire it just like the picture in post 11 with a plain old 12v bulb, no gauge, nothing else,no led,just 1 plain old 12v bulb switched power to it other side of light to terminal 1. If you wire it just like the pic in post 11 if the alternator is good the light will light when you turn the key and go off when the alternator starts charging. GUARANTEED!!!! You do have terminal 2 connected as before,correct?

Yep absolutely I have terminal 2 connected and I tried it as stated 12v to red wire on bulb ground to terminal 1 light stayed illuminated but alt was charging at 14.42 at about 2k rpm mind you this is a new alt I believe the issue is with the particular bulb I was using I’m going to find a different bulb holder to try

 

[Ricko1966]

Yep absolutely I have terminal 2 connected and I tried it as stated 12v to red wire on bulb ground to terminal 1 light stayed illuminated but alt was charging at 14.42 at about 2k rpm mind you this is a new alt I believe the issue is with the particular bulb I was using I’m going to find a different bulb holder to try

I want pictures. Lots of them. This mystery red wire bulb holder,the back of the alternator,the alternator plug,how and where you have things connected. You have something connected wrong or your new alternator has a problem.

 

[blackbird454]

I want pictures. Lots of them. This mystery red wire bulb holder,the back of the alternator,the alternator plug,how and where you have things connected. You have something connected wrong or your new alternator has a problem.

Yep will grab them in a few moments the bulb holder is the one coming out of a 2inch Temp gauge (bosch brand I believe)

 

[Ricko1966]

Yep will grab them in a few moments the bulb holder is the one coming out of a 2inch Temp gauge (bosch brand I believe)

That doesn't have 2 leads on it. How are you hooking power to one side and ground side to terminal 1?

 

[blackbird454]

Thar doesn't have 2 leads on it. How are you hooking power to one side and ground side to terminal 1?

Yeah it has a red wire and ground wire although the ground appears to be odd which is why I believe the bulb holder is my issue im going to purchase a 194 bulb holder such as this I believe that will work correctly and I can probably make it fit in the back of the cluster where the gen light is https://www.autozone.com/electrical...0K-GtuId_zO9NKOqe00OYOqbOaemn-YoaAiE9EALw_wcB

 

[blackbird454]

Thar doesn't have 2 leads on it. How are you hooking power to one side and ground side to terminal 1?

Alright there’s the bulb holder it appears that it grounds to it’s own frame once the bulbs inserted (maybe the issue) but I am running switched power from the fuse box in the cab (accessory) verified with multimeter several times the wire you see on term one with green tape (temp wire to verify ) coming from the ground side however the light would never go out if i hit term 1 with 12v charges immediately I depinned term 2 and ran it straight to the alt ( the factory exciter wire is still in the factory plug just for some insight as the the madness.

 

[Ricko1966]

Go under the hood hook the battery + to the red wire,hook the black wire to term 1. The light should come on. Start the truck the light should go out. Do this and verify that that happens.

 

[blackbird454]

Go under the hood hook the battery + to the red wire,hook the black wire to term 1. The light should come on. Start the truck the light should go out. Do this and verify that that happens.

Haven’t had a chance to confirm this yet I am going this afternoon to buy a 194 bulb socket (looks like it may fit in the gen light hole in the cluster) so if it does work it will become the new gen light lol I’ll update later tonight I can’t thank you enough for your time and knowledge you shared