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thanks CraigS. could you point me in the right direction for a "good" multimeter? there are so many options. I'm not sure what to look for.
Hi Chewy,

Pretty much any multi-meter has a current draw measurement function, but you have to break into the circuit to make the measurement. For current draws over a few hundred milliamps, you'll use a separate, dedicated socket for the probe (see the picture https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1). Your meter's instructions will show the proper connections.

Some multimeters have a lobster-claw-looking probe that goes around the wire under test, allowing you to measure the current without breaking the circuit. Last time I looked years ago, meters capable of measuring milliamps of DC current get expensive really quickly.

For your parasitic draw test, the less expensive meter is fine. You may need a helper to keep the alligator clips on each end of your battery circuit.


John
 

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Discussion Starter · #22 ·
The big question is, why did that happen? The fuse blew for a reason. You shouldn't just replace the fuse and move on.
I know, right? I chalked it up to a bad fuse. I've had both seat warmers on with no issues in the past. And since replacing the fuse, both seat warmers are working again. I figured if there was a short, it would blow immediately after turning the heaters on.
 

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I do have a kill switch, but it does have a low amperage self resetting fuse bypass. This allows the clock and ECU to get constant power if key is removed, but will blow if someone tries to start the car leading to a surge in amperage.
If only the clock & ECU have juice (when the Batt. kill switch key is removed),they might be the problem areas ,dunno.
 

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An old school simple parasitic drain test: Remove the neg battery cable. Put a test light between the battery and terminal. If the light goes on you have a drain. Start pulling fuses to find the circuit. Doesnt work well on newer systems that have small drains, but a dead short should really light the bulb bright.
 
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I found it hard to tell if a meter will measure that low. Most provide specs as to how much current they can measure. I found a couple that 'may' work though. Notice that this one has a separate plug to the red lead that is labeled mA.
Klein Tools MM600 HVAC Multimeter, Digital Auto-Ranging Multimeter for AC/DC Voltage, and Current, Temperature, Frequency, Continuity, More , Orange - - Amazon.com
I searched " multimeter to measure mA" and got a bunch of useful info. EMAC is correct and since it is a inexpensive test it could be a good first attempt. You could get a simple 12V single element bulb like this
Sylvania 89 Long Life Incandescent Mini Bulb (Pack of 2) 34229 | O'Rei (oreillyauto.com)
and a couple pieces of wire a foot long. Disconnect the battery cable and set it so it doesn't contact any metal. One piece of wire goes to the terminal on the battery and held against the small tip on the bottom of the bulb. The other wire goes to the battery cable end and to the silver metal around the base of the bulb. Probably a good idea to have a helper for extra hands.
 

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Discussion Starter · #26 ·
I found it hard to tell if a meter will measure that low. Most provide specs as to how much current they can measure. I found a couple that 'may' work though. Notice that this one has a separate plug to the red lead that is labeled mA.
Klein Tools MM600 HVAC Multimeter, Digital Auto-Ranging Multimeter for AC/DC Voltage, and Current, Temperature, Frequency, Continuity, More , Orange - - Amazon.com
I searched " multimeter to measure mA" and got a bunch of useful info. EMAC is correct and since it is a inexpensive test it could be a good first attempt. You could get a simple 12V single element bulb like this
Sylvania 89 Long Life Incandescent Mini Bulb (Pack of 2) 34229 | O'Rei (oreillyauto.com)
and a couple pieces of wire a foot long. Disconnect the battery cable and set it so it doesn't contact any metal. One piece of wire goes to the terminal on the battery and held against the small tip on the bottom of the bulb. The other wire goes to the battery cable end and to the silver metal around the base of the bulb. Probably a good idea to have a helper for extra hands.
thanks craig
I actually ordered this exact multimeter yesterday from amazon and just got notification that it was delivered already today. I went to my local ACE hardware and found it for $54 on the shelf. Bought it on amazon for $44 shipped next day.
Not sure how these brick and mortar stores are able to compete.
I also have a bulb tester as well. I should be good to go once I get everything hooked back up tonight.
 

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Discussion Starter · #27 ·
update
got the multimeter tool today. hooked the pos terminal back on the battery. plugged in my leads on the multimeter to the mA socket and turned dial to mA range. touched one side of the tool's probe to the neg battery terminal and the other to the neg disconnected battery cable. Getting a reading of "0.38" mA. not sure if the decimal is correct of if it should be reading "38 mA".
Anyway, started pulling fuses while my buddy was watching/holding the multimeter. no voltage drops but did have a temporary spike when i removed the EFI/coil and horn/4way flasher fuses, but then dropped back to the 0.38mA reading.
Also disconnected pos feed to the alternator w/o change/drop in current.
Plugged battery back in for several hrs and just went out to touch the alternator to see if it's warm. No difference in temp.
At this point, I'm going to check the voltage of the battery daily to see how fast and if it drains again.
If so, I'll pull my fuse to the seat warmers (turns out it was the wiper fuse, not the radio fuse) and see if that fixes the issue.
 

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You may have mention it at the beginning of the thread but I don’t recall. How old is the battery?
 

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Discussion Starter · #29 ·
You may have mention it at the beginning of the thread but I don’t recall. How old is the battery?
Less than 1.5 yrs old. Good old fashioned lead acid battery. 500CCA. had it checked out over the weekend at the battery shop and checked out ok.
 

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Not to throw a curveball your way as you work to figure out the issue, but it’s not entirely unheard of for a battery to test well yet have actual issues. If you find that you can’t figure out what’s draining it just keep that in the back of your mind. I had it happen with 2 “platinum” batteries in my old Powerstroke. They were 2 years old and I went through a new battery harness, alternator test, etc. I had just assumed it couldn’t be the batteries because they were fairly new and they would test well and charge on a traditional battery charger. But if they say longer than say 5-6 days they’d be nearly flat
 

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At 38mA, I am thinking that the battery is suspect. The first thing to do is to charge the battery up and while unplugged, check the voltage. It should read between 12.4v and 12.8v. Next to a simple load test. I would get a 12v light build that uses about 1A and plug it in. It should run for days. I would leave it on for 4-6 hours and see what happens.
 

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Discussion Starter · #32 ·
At 38mA, I am thinking that the battery is suspect. The first thing to do is to charge the battery up and while unplugged, check the voltage. It should read between 12.4v and 12.8v. Next to a simple load test. I would get a 12v light build that uses about 1A and plug it in. It should run for days. I would leave it on for 4-6 hours and see what happens.
battery was reading 12.4v fully charged at the battery store. I'll consider the light bulb test.
 

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You might want to have it tested at a different store just to cover all bases. 20 years ago as a Lexus tech we used one of the old adjustable load testers until Lexus sent us a new high tech tester. This all solid state thing told us the current battery state as well as 'state of battery life'. I had a car come in and used the new tester which said replace it. Service adviser asked me to re-test w/ the old one which said it was OK. 2 months later the advisor got an email saying the first tester was correct. He was on a trip and the battery died and he had to buy a new one. that was the last time I used the old tester.
 
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