Parasitic draw issue

[culturedredneck]

My 97 Fzj80 has sat parked for a few months, and during this time I noticed the battery was dying every 3-4 days. Having fixed a previous parasitic draw with the door close switch, I figured I could solve this one too. I ran through the routine of pulling all the fuses with the multimeter hooked up, and I couldnt find any issues at all. I swapped in a new battery since this one was older and had been drained and recharged a few times, and still no dice. Alternator is charging fine. I took the car to a mechanic who retraced my steps with an Amp Hound and ran a few other tests, and he couldnt find any parasitic draw either, but did confirm that something is still killing the battery every 3-4 days. Just before I parked it I had a mechanic disconnect the rear diff actuator unit due to my rear locked being stuck. I believe he left it disconnected while ordered a new unit.

Can anyone think of an obvious next step? Are there any known issues that would cause a draw on the battery, but not show up on a parasitic draw test?

Thanks in advance, this one has me stumped!

 

[TXMeatball]

Saw a video the other day of a tech that used a thermal imager to find one on an older f250.

 

[jonheld]

Use an ammeter. Typical quiescent draw should be between 20-30mA. Anything significantly over that can indicate an issue.
If you get a high reading, disconnect 1 fusible link at a time. Each one feeds a different sub-system. Once you isolate it to a link, go from there using the Toyota EWD.

 

[culturedredneck]

Use an ammeter. Typical quiescent draw should be between 20-30mA. Anything significantly over that can indicate an issue.
If you get a high reading, disconnect 1 fusible link at a time. Each one feeds a different sub-system. Once you isolate it to a link, go from there using the Toyota EWD.

The mechanic who is working on it now tested it with his his Amp Hound (which i believe is an ammeter) and confirmed that all fuses were within the 20-30mA range.

 

[jonheld]

The mechanic who is working on it now tested it with his his Amp Hound (which i believe is an ammeter) and confirmed that all fuses were within the 20-30mA range.

I don't know what that statement means.
The TOTAL quiescent draw from the battery positive terminal should be in the range stated. He should be measuring off of the battery, not individual fuses.

 

[culturedredneck]

I don't know what that statement means.
The TOTAL quiescent draw from the battery positive terminal should be in the range stated. He should be measuring off of the battery, not individual fuses.

I’m probably not explaining it correctly, since I’m not familiar with this method. Let’s just say that he confirmed that range with me when I asked about testing. If that were the case, would it still be possible to have a parasitic draw that doesn’t show up?

 

[ozarkmud]

If the draw is really high, and it may be high enough here, you can use a clamp amp meter to the positive or ground cable. You can then pull fuses to see what gets it under control.

 

[Brindleboxer]

What @jonheld is saying is test at the fusible link that is connected directly to the battery. With this method you can identify a system that is drawing the power and then focus on that system only. There are three "branches" on the fusible link all powering a sub group. Once again, as he stated you can then use the FSM (download under resources section) to troubleshoot.

I don't know your mechanic so I won't assume anything but I have been on this forum for years and @jonheld always gives sound advice, we just need to follow it.

 

[jonheld]

I’m probably not explaining it correctly, since I’m not familiar with this method. Let’s just say that he confirmed that range with me when I asked about testing. If that were the case, would it still be possible to have a parasitic draw that doesn’t show up?

There's no such thing as current that doesn't exist. Either it's there or it's not.
There are 3 fusible links bonded together as a set. Each one feeds a different sub-system. Please see the picture below.
As @Brindleboxer stated, I would attach an ammeter between the positive battery terminal and the fusible link bonded terminal. This will give you a reading of the TOTAL CURRENT DRAW FOR THE VEHICLE, as the only other connection to the positive battery terminal is the starter motor.

 

[Mark W]

Not feeling mentally energetic to put the effort into making deep analysis. I will toss this out, just because I have seen it a few times lately and it is therefore high on my list to check.

Check and make sure the green courtesy light around the ignition switch is not staying on full time.

Mark...

 

[jht3]

if the draw in consistent, it will show via meter at the battery.

but if its intermittent, like i had last year, it will pass all the static tests. what i discovered is my auto headlight relay was energizing itself, at random, and turning the headlights on over night. it could go weeks without issue, but then the next day i'd have a dead battery. what i found is the fuse in the kick panel was not making constant contact due to the female terminal in the fuse block. i was able to squeeze that terminal closer and its been perfect ever since.

 

[culturedredneck]

Thanks everyone for all the help so far. @jonheld Thanks for the detailed explanation, that all makes sense now.

Unfortunately I can't confirm anything 100% until the vehicle is back in front of me, but I did speak to the mechanic last night and he did say he checked between the positive battery terminal and fusible link, and the reading was in spec, between the 20-30mA. Obviously, I wasn't there so I cant verify.

If he is unable to solve the problem then I'll retest everything and start back from the beginning and see where that leads.

 

[TrickyT]

Sorry, late replying but I thought I would throw in some data from measurements I made a few years back in hopes it helps with your troubleshooting. These are measurements I made when nothing was wrong with my 80, but I wanted to record the parasitic current on the various circuits so that if I ever had a problem I would have known good values to compare to.

FZJ80 Parasitic Battery Loads — 26apr15

EFI: 2 mA
ECU-B: 5 mA
Dome circuit (clock, radio, antenna ecu): 5 mA
Scanguage: 4 mA (when sleeping)
Misc (undetermined -- RS3000 alarm?): 3 mA
Blue Sea ACR: 15 mA
2m radio: 9.2 mA
============
Total: 43.2 mA

Very likely some things don't apply in your situation (e.g., 2m ham radio or the automatic charge relay for my 2nd battery), but you can see that even with a lot of extra stuff the current draw is minimal. Like @jonheld said, 20-30ma.

I measured these values by pulling the various fuses for these circuits and then sticking the leads from a quality (Fluke) ammeter in place of the fuse. (Ignition off, of course.) I then measured the total drain at the battery by disconnecting the positive terminal and sticking my ammeter in between. It matched the total in the table above, so I was confident I had captured all of the circuits that had parasitic draws associated with them. From the brief internet search I did about the Amp Hound it looks like it does something similar, but I'm an old school (at this point quite old school) EE and always just use old school proven technology.

Back of the envelope math, but if you have a 75Ah flooded cell battery (so 1/2 x 75Ah useful capacity), then it should take 1,250 hrs (52 days) to drain the battery. So if yours goes dead in 3-4 days then you either have a bad battery or the parasitic draw is much great than 30ma.

Hope this helps!

 

[12bit]

do you have an aftermarket stereo installed?

 

[Trollhole]

Not feeling mentally energetic to put the effort into making deep analysis. I will toss this out, just because I have seen it a few times lately and it is therefore high on my list to check.

Check and make sure the green courtesy light around the ignition switch is not staying on full time.

Mark...

Love it. That's what I'm betting it is as well.

 

[culturedredneck]

@jonheld Alrighty, I've got my cruiser back in my garage now and unfortunately the mechanic wasn't able to fix the issue. I started trying to diagnose it myself based on your above recommendations. This is my first time using the amp setting on my ammeter, so not 100% sure if I'm doing this right. This was with the car completely off, and no key in ignition.

 

[culturedredneck]

Sorry, late replying but I thought I would throw in some data from measurements I made a few years back in hopes it helps with your troubleshooting. These are measurements I made when nothing was wrong with my 80, but I wanted to record the parasitic current on the various circuits so that if I ever had a problem I would have known good values to compare to.

Very likely some things don't apply in your situation (e.g., 2m ham radio or the automatic charge relay for my 2nd battery), but you can see that even with a lot of extra stuff the current draw is minimal. Like @jonheld said, 20-30ma.

I measured these values by pulling the various fuses for these circuits and then sticking the leads from a quality (Fluke) ammeter in place of the fuse. (Ignition off, of course.) I then measured the total drain at the battery by disconnecting the positive terminal and sticking my ammeter in between. It matched the total in the table above, so I was confident I had captured all of the circuits that had parasitic draws associated with them. From the brief internet search I did about the Amp Hound it looks like it does something similar, but I'm an old school (at this point quite old school) EE and always just use old school proven technology.

Back of the envelope math, but if you have a 75Ah flooded cell battery (so 1/2 x 75Ah useful capacity), then it should take 1,250 hrs (52 days) to drain the battery. So if yours goes dead in 3-4 days then you either have a bad battery or the parasitic draw is much great than 30ma.

Hope this helps!

Thanks for this breakdown. I know nothing about electronics, and this was a super helpful way to explain it. I posted some photos below, and it looks like I'm only drawing 2ma? I think that would be considered normal... Am I reading the meter right?

 

[george_tlc]

No, you are not using the meter correctly. If you look at the terminals, the CENTER is for mA (and volts etc), the right terminal is the 10A range. So, you are plugged into terminals to read 10A but are on the 200mA range. Possibly you are seeing 0.2A being displayed - depends how the meter is reading stuff. Anyhow, I'd suggest leave the terminals as you have them and rotate the knob to the 10A range. If it still displays 0.2 then you have 0.2A draw - which is TOO MUCH with everything 'off'.

cheers,
george.

 

[landcrshr]

...and the red lead goes on the positive battery post.

 

[culturedredneck]

No, you are not using the meter correctly. If you look at the terminals, the CENTER is for mA (and volts etc), the right terminal is the 10A range. So, you are plugged into terminals to read 10A but are on the 200mA range. Possibly you are seeing 0.2A being displayed - depends how the meter is reading stuff. Anyhow, I'd suggest leave the terminals as you have them and rotate the knob to the 10A range. If it still displays 0.2 then you have 0.2A draw - which is TOO MUCH with everything 'off'.

cheers,
george.

Thanks George,

I switched it to the 10 setting and it reads .02 now.