can parasitic draw be caused by wrong bulb size?
 

I have an 1156 light in an 1157 socket that wasnt working correctly for the turn signal, but i fixed it, and just now remembered that I also had the other bulb from that pkg in the cargo light. I am also suffering from a battery that drains if I dont drive the truck everyday. Is it possible this is related?

Re: can parasitic draw be caused by wrong bulb size?
 

Not likely a bulb issue. How is your stereo wired? Or any of your other add-ons for that matter. My stereo amp will drain my battery overnight if I don't have it shut off.

Re: can parasitic draw be caused by wrong bulb size?
 

I don't have a stereo yet, waiting to relocate the gas tank before I spend money on that. All I have changed that is remotely related to wiring is new light bulbs, added an edelbrock 1406 and cleaned up the rear light harness wires.
I did the test w the multimeter and the ground disconnected from the battery and red lead on the ground wire and black on the neg battery. the reading was around 12.7 which is about what it is when the truck is on. I removed each fuse 1 by 1 and no change.
The headlights tho are wired into a bolt on the frame by the battery then connected from there to the battery. this seems weird to me but I am brand new at this stuff and could be wrong.
when i disconnected that the reading went to 0 but the truck wouldn't start and the lights wouldn't work obviously.

Re: can parasitic draw be caused by wrong bulb size?
 

You want to check for an amperage draw. Set the multi-meter to amps. Then pull fuses 1 by 1 as you did before.

Re: can parasitic draw be caused by wrong bulb size?
 

pull all your fuses and turn everything off. then remove and replace each fuse , one at a time. when you go to install each fuse, if you see any sparking or arching when you go to install it that is the part of your system that the drain is comming from. from there you must do some investigative trouble shooting on each circuit attached to that fuse

Re: can parasitic draw be caused by wrong bulb size?
 

2 things come to mind...we are assuming there is a parasitic drain...

1 / How old is the battery? It could just be a bad battery...

Start your drain tests using the multi meter set to Amps...

WARNING! Do not attempt to start the engine with the multi meter inline with the battery and positive lead...

Remove the positive lead from the battery and connect the multi meter in series between the battery and the positive lead. With everything OFF, doors closed, lights off, etc....there should be zero 0 amps being drawn.
If there is any amp draw showing, immediately unplug the alternator feed wire.

If the amp draw drops to zero, the alternator or the regulator needs to be repaired...or replaced...

If after unplugging the alternator you still have a current draw...start looking at removing fuses one at a time...when the draw drops to zero...you have found the circuit causing the draw...look for dash lights back feeding, fans running etc...

Re: can parasitic draw be caused by wrong bulb size?
 

Don't know the bulb number for the cargo light but do know its single filament with 2 poles, one positive and one ground, the 1156 in that socket could short out the circuit.

Re: can parasitic draw be caused by wrong bulb size?
 

Did you say you only have 12.7 at the battery with the truck running or did I read it wrong?

Re: can parasitic draw be caused by wrong bulb size?
 

Do you have the choke wired direct or key on?

Re: can parasitic draw be caused by wrong bulb size?
 

yes 12.6-12.7 on the battery, the choke is wired to ign on the fuse box. i also tested with that disconnected same result.

Re: can parasitic draw be caused by wrong bulb size?
 

You should have roughly 14 V at the battery with the engine running. Is your alternator any good?

Re: can parasitic draw be caused by wrong bulb size?
 

Yes when it’s running it’s just over 14

Re: can parasitic draw be caused by wrong bulb size?
 

Through your comments i realized I didnt have it on the correct setting.
I did the test again, and now its showing -.75
is that an appropriate amount meaning I dont really have a draw? I am wondering if I just drained it w the dome light and/or ignition on and didnt realize it

Re: can parasitic draw be caused by wrong bulb size?
 

A 0.75 Amp draw is too much, assuming nothing is turned on or running...

Start deeper check by unplugging the battery wire to the alternator and the plug and note the Amp reading....if it is now zero...the Alt has a slow draw and needs an overhaul or replacement....

If it is still at 0.75 Amps, start removing the fuses one by one...have someone check the multi meter for each removal...if no change, put the fuse back in...

There will be one fuse that will drop the readout to zero...it is on that circuit that you have the slow draw...

:chevy::chevy::chevy:

Re: can parasitic draw be caused by wrong bulb size?
 

I think he is saying MINUS .75 which can't be right but I've seen multi meters bounce around depending on quality and low batteries.

Re: can parasitic draw be caused by wrong bulb size?
 

If he swapped the leads around it would read + 0.75....

I have seen - readings all my life and never worried about them...just means the meter leads are backwards...

CMG CMG CMG

YVEHC YVEHC YVEHC

Re: can parasitic draw be caused by wrong bulb size?
 

after all of the cursory tests check out out good, I'd look at the regulator/alternator..

b/o diode in the rectifier can discharge battery when not running and still charge battery when running..

good luck!

Re: can parasitic draw be caused by wrong bulb size?
 

Disconnected the alternator and it went down to .33

Re: can parasitic draw be caused by wrong bulb size?
 

lol

Re: can parasitic draw be caused by wrong bulb size?
 

OK...is the alternator a single wire unit of a 4 wire unit with external regulator?

Re: can parasitic draw be caused by wrong bulb size?
 

External. I put the new alternator on and no change. I will change the regulator tomorrow. thanks so much everyone i really appreciate the help!

Re: can parasitic draw be caused by wrong bulb size?
 

The answer to the original question is no.
A - current flow means you have the meter leads connected backwards of what the meter thinks is right. Actual current flow direction theory is up for debate, but makes no difference.
Swapping parts for no real reason wastes money. That's called shotgunning. Troubleshoot.

Electric systems are simple, but hard to figure out. A circuit is a circle from the source and back through a load. A load is something like a group of lights such as park lights or whatever. From the battery/alt the exact same current flows to and from said circuit. Its a circle. Nothing is lost or gained in the circle.
E=IR
or elecromotive force, (Volts) is equal to current times resistance. You can transform that w/ simple algebra.

Re: can parasitic draw be caused by wrong bulb size?
 

Disconnecting the blue and white wires from the alternator cuts the reading from .75 to .35. Does this mean the voltage regulator needs replaced or something else all together?

Re: can parasitic draw be caused by wrong bulb size?
 

Post a pic of the alternator and the voltage reg...

The results so far show most likely a faulty circuit diode in the alternator.

But you also have a secondary draw loss...most likely a bad regulator...

Unplug the wiring to the regulator and retest draw...

If its now zero, you have both of your draws identified...

:chevy::chevy::chevy:

Re: can parasitic draw be caused by wrong bulb size?
 

I put a new voltage regulator and it read 2.2 so I put the old back on. Now it’s reading .65
Am I wired wrong? I didn’t use the river bushing grommet things on the new install

Re: can parasitic draw be caused by wrong bulb size?
 

Unplug the regulator and let us know the draw ..ign off...

Thanks

Re: can parasitic draw be caused by wrong bulb size?
 

.95

Re: can parasitic draw be caused by wrong bulb size?
 

Thanks Captain Obvious. Nice Google search.

Re: can parasitic draw be caused by wrong bulb size?
 

Different reading with the alternator can be misleading. This is because on a lot of older cars/trucks, the alternator wire runs to the starter solenoid, and sometimes there are other factory/accessoriesattached there or at the alternator stud itself. The OP needs to be familiar with meters and settings. When you originally said .75 amp draw, I am unsure of if you know what the actual reading is.... .75 amps, 750 milliamps, .750 milliamps? the first thing I would do is buy a small cheap battery load tester and test the battery. You can also start the vehicle, let it run for at least 10 minutes, write down the battery voltage running, then take off the battery terminals as quickly as possible and hook your meter leads to the battery. Write down what you first see when you hook up the leads, then what it finally settled at.

Re: can parasitic draw be caused by wrong bulb size?
 

Another way to find a parasitic draw is to place your meter in milivolts range and place the meter leads across each fuse. A circuit carrying current will show a small amount of voltage drop across the fuse.

Re: can parasitic draw be caused by wrong bulb size?
 

In my opinion, it won't be the bulb, if it's a regular bulb type. LED's can operate on minimal power, so the slightest residual power left through the switch could drain power, but if it was the middle of the night and dark outside, you would see the light on, dimly lit.if you want to "throw parts at it", replace the wrong bulbs with the correct ones. But as long as the power requirement on the incorrect bulbs you installed are at or above the correct bulb specs, it's not going to drain unless the actual light is left on. When the switch is off, there is no or very little residual power to the bulb.

Re: can parasitic draw be caused by wrong bulb size?
 

Found it! The PO removed the horn for some reason but the horn relay switch was plugged in. The steering wheel is pretty hammered and there isn’t even a spring in it for a horn button.. I’m thinking they couldn’t get it to work with this “new” steering wheel.. I’ll find a new one soon enough but I think I’m good on the parasitic draw and I have a shiny new alternator lol

Re: can parasitic draw be caused by wrong bulb size?
 

OK I didnt have it like I thought.

when I disconnected the horn relay, I also had the external regulator disconnected so the reading went to 0

if when I disconnect the external regulator the reading goes to 0, is that indicative of a faulty relay?

I purchased a replacement external regulator and connected it, the reading went up to 2.35, so I put the old one on and we are still at .80
I did not however turn the truck on so maybe it didnt get a chance to "activate"?