Parasitic battery draw

[andrewpclayton]

Here’s where I am so far..

Disconnected neg terminal connected multimeter and the reading is .80

I broke a bolt in the old one so I have a new alternator

New external regulator, but it’s buzzing really loud so I think it’s not grounded well? I ordered new rubber grommets for mounting, its mounted directly to the radiator support now.. When I unhook the external regulator the reading goes to 0
I unhook the blue and white wires from the alternator and the reading goes to .35

I unhooked every fuse in the fuse box and the turn signal relay and the reading remained at .80

Also unhooked the electric choke, disconnected the horn relay as I don’t have a horn
Still at .80

I disconnected the wiring harness coming from the cab on the drivers side and the reading went to 0, so does that mean it’s in the cab somewhere?

Is there something in the cab that’s not on a fuse that I haven’t thought to check? I’ve read every post I can find and I am out of ideas

Any thoughts?

[andrewpclayton]

Here’s where I am so far..

Disconnected neg terminal connected multimeter and the reading is .80

I broke a bolt in the old one so I have a new alternator

New external regulator, but it’s buzzing really loud so I think it’s not grounded well? I ordered new rubber grommets for mounting, its mounted directly to the radiator support now.. When I unhook the external regulator the reading goes to 0
I unhook the blue and white wires from the alternator and the reading goes to .35

I unhooked every fuse in the fuse box and the turn signal relay and the reading remained at .80

Also unhooked the electric choke, disconnected the horn relay as I don’t have a horn
Still at .80

I disconnected the wiring harness coming from the cab on the drivers side and the reading went to 0, so does that mean it’s in the cab somewhere?

Is there something in the cab that’s not on a fuse that I haven’t thought to check? I’ve read every post I can find and I am out of ideas

Any thoughts?

[toolboxchev]

Aftermarket Radio with 2 power or positive connections. One is for memory.

I would run back through the fuse panel again, look for mods done by a previous owner.

[andrewpclayton]

I don’t have a radio.. I’ll look closer but so far all looks normal

[VetteVet]

Check the brown wire in the regulator for 12 volts with the key on and zero with the key off. If you get 12 volts with the key off then you have a problem in the cab.

Do you have an idiot light or the battery gauge. If it's the battery gauge, find the two wires to it and pull the fuses to see if the draw goes away. One is by the battery and one is by the left headlight. They are small wires and the fuse holder looks like a tiny football.
The regulator must be grounded to the support and to the alternator.
Mounting it in the grommets does not ground it. Run a short wire from the cover screw to the support and another wire to the alternator body. This won't help the draw but it will help the alternator charging. It's probably the reason for the buzzing.

I'll check in later to see what you find.

[demian5]

I had my horn contacts on my steering wheel stick on (but horn was disconnected so didn't hear). That drained it pretty good.

[Gromit]

Also this is less likely but if interior light is switched on (with the headlight switch) but the light is not working and the wire that runs under the sill plate has a short...

[andrewpclayton]

Checked the brown wire at the regulator, it was getting 12 key on and off so it’s in the cab

Disconnected the ignition switch and the reading went to 0. Not sure what to do with that tho or if that is even helpful

[VetteVet]

Your brown wire at the regulator is connected to the key switch and shares the same terminal as a 12 gauge brown wire that feeds the fuse panel ACC stuff, wipers, heater motor, turn signals,. It is a 16 gauge brown wire to the firewall block and insde the FB it becomes a 10 ohm resistance wire to excite the regulator.

If you are getting juice through the key switch with the key off to the ACC terminal then you should have power on those fuses with the key off as well. The drain would show up as long as the regulator was plugged in because the brown wire is hot even with the key off. so it is closing the contacts in the regulator causing the drain.
this is why pulling the fuses did not stop the drain.

My suspicion is that the key switch is feeding the ACC terminal with the key off and you will see voltage on the fuses that the 12 gauge brown wire feeds with the key off. The wipers heater fan turn signals etc. will work with the key off as well.

I had a member with this exact problem a few weeks ago and it turns out that he had a burned connector on the key switch from years of heating and it had cause a short between the red power wire and the ACC wire in the key switch plug. Yours is not that because the draw went away when you disconnected the Ign switch.

Check the switch for continuity between the battery terminal and the ACC terminal with the key off and if it shows 0 ohms then there's your problem.

Here's the key switch with the black arrows showing the two wires. the 24 gauge wire is the resistance wire to the firewall block which connects with the 16 gauge brown wire to the external regulator. It shares the same terminal (ACC) with the 12 gauge brown wire that runs to the fuse panel.




Here's the 12 gauge brown wire going to the fuse panel to feed the wipers turn signals heater fan etc. It has a black arrow on it also.

[Steeveedee]

Another possibility- make absolutely certain that when you take the key out of the ignition switch, that it is in the "off" position. My truck's key can be taken out in any position (going to get another), and one of my sons took the key out with the switch in the "Acc" position, because "all the way counterclockwise" is the way all the new cars have been for decades. When I went to drive it 4 days later, I had a dead battery. You can't always tell, with a gauge setup, because there are no idjit lights indicating that there is power to the electrical system with a gauge setup, and you won't see that small a draw on the system, looking at the ammeter (which is what that gauge is, even if it says "Battery", which most people would think to mean "Volts". Actually, ALL gauges are ammeters, (except for mechanical oil and temp gauges, of course) but we can discuss that some other time.

Not trying to insult your intelligence, BTW, it's just something that came to mind.

[andrewpclayton]

Originally Posted by VetteVet

Your brown wire at the regulator is connected to the key switch and shares the same terminal as a 12 gauge brown wire that feeds the fuse panel ACC stuff, wipers, heater motor, turn signals,. It is a 16 gauge brown wire to the firewall block and insde the FB it becomes a 10 ohm resistance wire to excite the regulator.

If you are getting juice through the key switch with the key off to the ACC terminal then you should have power on those fuses with the key off as well. The drain would show up as long as the regulator was plugged in because the brown wire is hot even with the key off. so it is closing the contacts in the regulator causing the drain.
this is why pulling the fuses did not stop the drain.

My suspicion is that the key switch is feeding the ACC terminal with the key off and you will see voltage on the fuses that the 12 gauge brown wire feeds with the key off. The wipers heater fan turn signals etc. will work with the key off as well.

I had a member with this exact problem a few weeks ago and it turns out that he had a burned connector on the key switch from years of heating and it had cause a short between the red power wire and the ACC wire in the key switch plug. Yours is not that because the draw went away when you disconnected the Ign switch.

Check the switch for continuity between the battery terminal and the ACC terminal with the key off and if it shows 0 ohms then there's your problem.

Here's the key switch with the black arrows showing the two wires. the 24 gauge wire is the resistance wire to the firewall block which connects with the 16 gauge brown wire to the external regulator. It shares the same terminal (ACC) with the 12 gauge brown wire that runs to the fuse panel.

Attachment 1699788


Here's the 12 gauge brown wire going to the fuse panel to feed the wipers turn signals heater fan etc. It has a black arrow on it also.

Attachment 1699789

Can you explain checking the ign switch for continuity? This is so far outside of my comfort zone I’m trying my best to follow

[andrewpclayton]

Would a new key switch solve what you’re thinkin here? I was planning on getting a new one anyway as mine is going what steeveedee’s does with the key coming out of the ignition when it’s on.. or would a whole rewriting kit fix it? I need this truck to be reliable so whatever it takes

[demian5]

Originally Posted by andrewpclayton

Would a new key switch solve what you’re thinkin here? I was planning on getting a new one anyway as mine is going what steeveedee’s does with the key coming out of the ignition when it’s on.. or would a whole rewriting kit fix it? I need this truck to be reliable so whatever it takes

Did you confirm the accessorys work with the key off as VetteVet said?


Don't start throwing part at it yet. Keep hunting.

[VetteVet]

Originally Posted by andrewpclayton

Would a new key switch solve what you’re thinkin here? I was planning on getting a new one anyway as mine is going what steeveedee’s does with the key coming out of the ignition when it’s on.. or would a whole rewriting kit fix it? I need this truck to be reliable so whatever it takes

Based on what you said I think a new switch is in order. The other checks don't seem to fit this problem, however if the key switch was not completely off you would see those power on items.

[andrewpclayton]

Heater fan motor and turn signals work with key off, wipers do not.

Did a continuity check w key off, it beeps when connected to brown and the other smaller gage brown terminal, and when it’s the big brown and the pink. Does not beep when it’s red and bigger brown wire.

Is this still consistent with needing a new ign switch? Store in town has one I just called

[Steeveedee]

For sure the heater blower motor and turn signals should not work with the key off. Emergency flashers, yes, but unless they are on you won't see a drain. It would appear that some wires are connected incorrectly. That doesn't mean it's the ignition switch as a certainty, though. If you don't like the fact that the key comes out in any position, you could replace the switch, but without expectation that it will be certain to correct this problem.

Edit to add- if you buy a new switch, it may be that the lock cylinder is the actual culprit, and a new switch won't correct for that. Getting a new lock cylinder will mean that, unless you take it to a locksmith, the door keys will not match the ignition. I'm in that boat with my truck, currently. It can be considered a feature, since some thieves pop out a door lock and go back to their vehicle where they cut a key and take your truck. Joke's on them, if they do so, and the ignition key is different.

[andrewpclayton]

I found it! Steeveedee was right the ignition switch was poorly mounted so the key was loosely just kinda flopping around. I was pulling it out in the ACC position every time. I didn’t realize the acc was all the way to the left until I was starting to put in the new ignition switch I bought.

Thank you all so much I can’t begin to tell you all how much I appreciate your help. I’m on these forums every day learning so much