Scratching my head

[jackwarner22]

I recently purchased a 1982 k10 with a c20 cab. It is a running and driving truck. Recently I have developed a severe draw. With the headlights, heat, brake lights, reverse lights. They all draw. Going down the road doesn’t help. Will drop as far as the truck not running if not shut off. When headlights and heater are shut off the volts return. I have a 6 month old battery and have replaced the alternator. No change. Re run block to battery grounds and Ran a cab to battery ground. Any help is appreciated.

 

[EvilGenius]

My guess is check the condition of your battery positive wires at this point. If you've eliminated the grounds as an issue that is.

The coil will probably have a cutoff voltage where it stops working. So with everything on the voltage provided to the coil must be falling below this level. Start with the fusible links maybe?

 

[Ricko1966]

Have you checked output on the alternator,old one or new one? You could have a broken or disconnected voltage sensing wire. Or a 2 bad alternators. But find out if your alternator is functioning properly.

 

[Grit dog]

Separate whether you have an excessive current draw or lack of charging current.
You haven’t provided enough info to discern that from here.
First just check charging voltage at the battery. Whatever the battery is at rest 12.xx or whatever even if it’s a bit discharged.
Then voltage at idle should be 13.xx -14v. Idk exactly but should be way higher.
If that’s good then start isolating components. And check residual amp draw at the battery.
More info needed to diagnose further.

 

[87chevy_com]

second what @Grit dog said.
also what does "Re run block to battery grounds and Ran a cab to battery ground" mean, did you buy off the shelf parts, or home made?

If it has a draw, use a volt meter and measure the fuses to help isolate the circuit that is drawing current. youtube how to do that. you can voltage drop the battery cables aswell. There should be almost no voltage drop when going from batter terminal, to battery cable lug.

clint

 

[Strick]

As mentioned before, start with the battery. When reading your list of problems I would go to the headlamp switch as all the lights are routed through it. Be sure to check the ground gang that is over the fuse box too. It's not easy to get to but often times windshields leak & the water trails directly to that spot.

 

[Grit dog]

As mentioned before, start with the battery. When reading your list of problems I would go to the headlamp switch as all the lights are routed through it. Be sure to check the ground gang that is over the fuse box too. It's not easy to get to but often times windshields leak & the water trails directly to that spot.

Wow bud! Thats a tip from experience with these trucks! Good stuff!

 

[Strick]

Wow bud! Thats a tip from experience with these trucks! Good stuff!

Dad bought his 79 new & this has been an issue with it a couple times. I have the dash torn out now so that I can fix the problem again. I've been baptized by fire with dad's Crew. Maybe it'll help someone else along the way.

HS

 

[jackwarner22]

Have you checked output on the alternator,old one or new one? You could have a broken or disconnected voltage sensing wire. Or a 2 bad alternators. But find out if your alternator is functioning properly.

Pulled the alternator off of a good motor that ran and drove with no voltage issues less than a month ago so I can’t imagine it’s in the alternator but will check the plug and the wires running from it. Thanks

 

[jackwarner22]

As mentioned before, start with the battery. When reading your list of problems I would go to the headlamp switch as all the lights are routed through it. Be sure to check the ground gang that is over the fuse box too. It's not easy to get to but often times windshields leak & the water trails directly to that spot.

I isolated it a little (I think) my dimmer switch has individual wires opposed to the original 3pin plug. So I pulled the 12v power wire and the other accessories still draw. Is the ground gang the 6 pin block? Thank you for the help!

 

[jackwarner22]

As mentioned before, start with the battery. When reading your list of problems I would go to the headlamp switch as all the lights are routed through it. Be sure to check the ground gang that is over the fuse box too. It's not easy to get to but often times windshields leak & the water trails directly to that spot.

The battery was 8years old and I replaced that thinking it was the issue as well.

 

[jackwarner22]

second what @Grit dog said.
also what does "Re run block to battery grounds and Ran a cab to battery ground" mean, did you buy off the shelf parts, or home made?

If it has a draw, use a volt meter and measure the fuses to help isolate the circuit that is drawing current. youtube how to do that. you can voltage drop the battery cables aswell. There should be almost no voltage drop when going from batter terminal, to battery cable lug.

clint

I will look into how to tell what is drawing with a volt meter. Believe that will be my next step thanks.

 

[Strick]

Yes, it's a 6 spade gang.