2005 4runner, 200,000 miles , battery draining randomly

toolhawk

Full Member
Joined
Mar 3, 2007
Messages
100
Points
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Make
Toyota
Model
4runner
Year
2004
Miles
200,000
Engine
4.0
05 4runner , 200,000 miles , Anyone here have any history of any relays getting stuck open and draining the battery... or? I have an issue with something draining the Battery randomly, could do it overnight or could do it over a period of four or five days when sitting or it may not do it at all. I did replace the battery thinking maybe it had a dead cell.. and it OLD! . had back surgery so the vehicle sitting probably for the next 3 months but It allows me to check every day. I'm Going Out every day with the Muti meter testing It .. stays fully charged days and then next day it's dead (4 volts).. If I could catch the voltage dropping slowly while it's parked I could start playing with relays ( fuses) and or ? to try to find the issue.. No, add ons to where a screw went through a wire. Everything works as it should on the vehicle. This is my second vehicle so I can sit and play with it for as long as I need as I have another vehicle to drive when I can start driving again? Thanks for any Ideas
.p.s New battery and I tested new battery.
Vehicle sat at hospital for 10 days... came out Started right up, wife drove it home, parked in driveway... went to move three days later It was completely dead, Fully charged battery, now it's been sitting for about 5 days Holding the charge ... this has been happening like this roughly for 2 plus months. ... alternator test good also.. Thanks!
 

billr

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Clamp-on DC ammeters are getting inexpensive enough that I'm thinking you should check parasitic current draw every time you shut the engine off. When you hit an occasion when draw is higher than usual, you can start pulling fuses/relays or flicking switches on/off For me, on an old Chevy, it was the ignition switch. If the steering wheel wasn't wiggled until the anti-theft pin fell into place to lock the wheel, then the somtimes the ignition switch/lock didn't move fully into the "off" position. The ignition would kill and the key come out, but the alternator control circuit was still powered. Took me a long time to find that one!

Before you rush out and buy an ammeter, let me try my son's meter on a couple of cars and see if it can reliably detect normal parasitic draw. I will post results later today. Brand of meter, too, just for reference.
 

toolhawk

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Clamp-on DC ammeters are getting inexpensive enough that I'm thinking you should check parasitic current draw every time you shut the engine off. When you hit an occasion when draw is higher than usual, you can start pulling fuses/relays or flicking switches on/off For me, on an old Chevy, it was the ignition switch. If the steering wheel wasn't wiggled until the anti-theft pin fell into place to lock the wheel, then the somtimes the ignition switch/lock didn't move fully into the "off" position. The ignition would kill and the key come out, but the alternator control circuit was still powered. Took me a long time to find that one!

Before you rush out and buy an ammeter, let me try my son's meter on a couple of cars and see if it can reliably detect normal parasitic draw. I will post results later today. Brand of meter, too, just for reference.
THANK YOU !!
 

billr

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Using an Ames CM1000A meter ($100 at Harbor Freight) I can detect whether the interior "dome" light is on or off. Incandescent lamps, drawing about 1/4A. Your only real problem will probably be trying to find a single cable to clamp around. Most battery cables now split right at the battery terminal, with several grounds and positive splitting to the starter, PCM, and everything else. This meter has a 1000A range, but I don't think many DIYers will have any use for that. I would be happy with a 400A maximum range, and would expect better reliability/accuracy at low readings if the max is lower. Just sayin'...
 

grcauto

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A module is not going to sleep every time. Likely the BCM due to a switch that is intermittent. If you can just check each time 30 minutes after shut down and it it's high you can start pulling fuses. Modules first. BCM the very first.
 

Haeynous

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Feb 5, 2024
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Tracing down an intermittent parasitic drain on a vehicle can be a very time consuming process. The key to tracking it down is making extreme effort not to disturb the vehicle's electrical state when testing. On modern cars simply having the key fob too close to the perimeter sensors can send many modules into a wake up mode that draws very low amperage and may appear to be an intermittent drain. I've had cars in my shop for two months before having the correct conditions and testing to positively identify a drain. Drains as low as 50 milliamps can zap a battery in a few days depending on battery health and amp/hour ratings. I don't have an amp meter that reads lower than 100 milliamps that has a clamp large enough to go around a battery cable, so I have made a wire loop to install between the battery and cable end that amplifies the reading by 10 and is small enough for my lower amp meter can clamp around it.

The number one issue I have encountered with all of the parasitic draw complaints has actually been the battery. The digital battery testers that are widely used are only about 85% to 95% accurate in finding a faulty battery. When people are told their battery is good the most popular explanation for loss of voltage over time is an electrical draw. Find someone who has an actual carbon pile load tester and have your battery tested with that method as well. The second most common cause of electrical drain issues is aftermarket equipment. I would say nearly half of the parasitic drains I locate are aftermarket stereos or devices that either have an internal fault or cause the vehicle network to stay active when it should go to sleep. Many times aftermarket radio drains will be intermittent. Another common issue is water damage in a connector. When tracking down an electrical drain I will scan the vehicle for signs of water intrusion and ask the owner if they have noticed any water leaking into the vehicle.

Good luck.
 

billr

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I sounds like you are a well-experience professional. I hope you stick around with us for while!
 

toolhawk

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Joined
Mar 3, 2007
Messages
100
Points
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Tracing down an intermittent parasitic drain on a vehicle can be a very time consuming process. The key to tracking it down is making extreme effort not to disturb the vehicle's electrical state when testing. On modern cars simply having the key fob too close to the perimeter sensors can send many modules into a wake up mode that draws very low amperage and may appear to be an intermittent drain. I've had cars in my shop for two months before having the correct conditions and testing to positively identify a drain. Drains as low as 50 milliamps can zap a battery in a few days depending on battery health and amp/hour ratings. I don't have an amp meter that reads lower than 100 milliamps that has a clamp large enough to go around a battery cable, so I have made a wire loop to install between the battery and cable end that amplifies the reading by 10 and is small enough for my lower amp meter can clamp around it.

The number one issue I have encountered with all of the parasitic draw complaints has actually been the battery. The digital battery testers that are widely used are only about 85% to 95% accurate in finding a faulty battery. When people are told their battery is good the most popular explanation for loss of voltage over time is an electrical draw. Find someone who has an actual carbon pile load tester and have your battery tested with that method as well. The second most common cause of electrical drain issues is aftermarket equipment. I would say nearly half of the parasitic drains I locate are aftermarket stereos or devices that either have an internal fault or cause the vehicle network to stay active when it should go to sleep. Many times aftermarket radio drains will be intermittent. Another common issue is water damage in a connector. When tracking down an electrical drain I will scan the vehicle for signs of water intrusion and ask the owner if they have noticed any water leaking into the vehicle.

Good luck.
 

toolhawk

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Thank you for the detailed write up.. I do know the battery is good as this is a second new battery with issue, And both were purchased brand new and Brand name battery ... battery does not bleed down at all when completely disconnected from vehicle.... Nothing after market on vehicle.... And no evidence of water leak anywhere. I do believe there's something being woke up due to the randomness of this issue.... A GM engineer told me about an issue they had with an hvac evac system being woke up for emissions in the middle of the night on vehicles and it would get stuck open and completely drain battery...
 
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