The BEST Way TO Perform a Parasitic Draw Test

This guy was clean shaven when he started looking for the draw.

I chased a parasitic draw on my 2010 Ram for months. I even took it to a dealer and a local shop after I failed to find the culprit. They couldn't pinpoint it either. I checked everything...or so I thought. Just by dumb luck, I dropped something in the driveway at night and it rolled under my truck. I glanced up and saw a faint light in the engine bay. Turns out that the hood latch (and the hood light actuator/switch) was slightly askew. The hood would latch, but since the latch was out of position, the light switch never disengaged. Makes sense that this light would never show a draw as I would disconnect the hood light at the bulb connector since I had the hood open testing for current draw. Crazy stuff, but I learned a lot from videos like this one. Hopefully, my story helps someone out. Thanks!

I've been a master tech for 25 years and never once did I think about physically latching the doors etc. And this is a great method for finding gremlins. I'm glad I found this channel, as unusual even as good as I am in still learning! Awesome video

Some of the new fuses now don’t have the test spots on the back because engineers decided that was too handy and they pride themselves in making things more difficult for us mechanics. Great video man

I’ve used this method with success several times. I’ve recently learned an extra hint to go along with this test. Prior to testing each fuse(especially with vehicles with a large amount of fuses), use a thermal image camera to look at the fuses. The one with the draw will show up warmer than the rest. Helps pinpoint the circuit quickly.

I've been a tech for over 25 years. I thought I was pretty good at electrical diagnostics. This video set me straight. What a great technique. Thanks for these videos. I wish these were around in the 90's.

I've been a master tech DIYer , weekend warrior, shade tree mechanic , jack of all trades master of none, under sensai mr Miyagi, for the past 30 years never ever seen such a great great video'. Thanks!

For new viewers, just an observation that 1006 milliamps is just over 1 amp, not 0.1 amp as was said at 7:06. Humble Mechanic has acknowledged that he mis spoke in old comments below.

Had a draw on a skid steer. Not as much out there for help with equipment as there is for automotive. A fuse panel is a fuse panel so I administered your test and used in line amp draw method. Ended up being a bad starter. Thank you for taking the time to share the knowledge

Car newbie here. I was super excited to try what you talked about. I had to do several adjustments and it took me quite awhile to understand everything, but I found out I had such a huge draw by my burglar alarm I had to adjust my meter up to volts from millivolts to get reading. I sure hope you have a video about this now. Thanks, a very informative video.

Found your channel through engineering explained and couldn't be happier I did. I love learning as much as possible about cars since I do all of my own maintenance as well as repairs when I feel confident enough in doing so. Looking forward to watching as many of your videos as I can thanks for what you do for us.

This guy is easy to watch and always adds little touches of experience that simply following an instruction manual doesn't give you. Always good to see a Humble Mechanic video appear in my Google search results...

I feel we are blessed to have you and several others on YouTube sharing your knowledge with us . Those who do not wish to learn and those jealous of your knowledge and capabilities will always try to discourage others . I am 51 and wish training videos like yours were available when I was in my teens . Truly truly helpful . Thanks for all your work .

Thank you so much for this. I have been trying to figure out how to do a parasitic draw on my homebuilt aircraft and none of the aviation sites were any help. I've been looking for exactly this info for weeks. Seems so easy once someone explains it to you. I appreciate you taking the time to post this.

Qualified automotive electrician for 15 years and have never seen this method before! Seems way superior! Never too old to learn something new 🤙 cheers!

One small correction to note. 1006 in speaking of amps is 1.006A not .1A, simple mistake but for students it could be detrimental when they are struggling to understand 1000mV is 1V ect. Good video, glad to see other putting things out like this to help promote the industry.

When I worked as a diesel mechanic it was always aftermarket shit. Even high end GPS trackers that were tamperproof. Always start with aftermarket add ons.

I've tried to explain this technique in words to people on a number of occasions, but they generally do not get it. Thanks for the excellent video.

Mr. HM, you are excellent at presenting and maintaining your audience. I love learning and your videos are just that: excellent learning tools. Cheers!

Its very important to check fuses before start metering. If a fuse is blown you might have 12v on one side and ground on the other (through a windshieldmotor or windowheater etc) and your multimeter might get damaged when measuring up to 300mV. Set meter to 20v dc atleast and do this test before switching over to 300mV.