What the heck is draining my battery....

[nchacon1984]

When I purchased my 4R it ran great. No issues. I’ve slowly have started upgrading or replacing things in it. Starting with seats, carpet etc. Then moved to replacing my interior lights with LEDs. Besides the interior bulbs, I’ve done nothing else electronically. So now, I’ve been having the problem where I’ll come out to use the 4R and it’s completely dead. I’ve replaced the battery and alternator this past Saturday. From Sunday to Wednesday night, I had no issues. It’ll turn over, come to crank it today...completely dead again.

Any ideas what it could be?

 

[calimobber]

When I purchased my 4R it ran great. No issues. I’ve slowly have started upgrading or replacing things in it. Starting with seats, carpet etc. Then moved to replacing my interior lights with LEDs. Besides the interior bulbs, I’ve done nothing else electronically. So now, I’ve been having the problem where I’ll come out to use the 4R and it’s completely dead. I’ve replaced the battery and alternator this past Saturday. From Sunday to Wednesday night, I had no issues. It’ll turn over, come to crank it today...completely dead again.

Any ideas what it could be?

How ling did you have it where it ran good? was it a long time or still recent?

 

[nchacon1984]

How ling did you have it where it ran good? was it a long time or still recent?

Ran good up until June/July when I installed the LEDS but sat from April to June, drove it sporadically in July, then sat the rest of the year til maybe from Christmas to now. That’s when I noticed it kept draining by battery. Figured they were just old and tires so I replaced them.

 

[LittleCaesar]

Start with this:
https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

 

[wcjeep]

Start with this:
https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

That's a great link. Recommend OP do exactly as shown. Helps if you can have recreate the conditions as the vehicle sits. Lights off. No accessory on. Something could have been pinched during carpet swap. Be sure your multimeter is set to AMP. Most multimeters require moving one of the leads to the "10A" port as well as setting the dial to "10A".

 

[Ruiner]

When I purchased my 4R it ran great. No issues. I’ve slowly have started upgrading or replacing things in it. Starting with seats, carpet etc. Then moved to replacing my interior lights with LEDs. Besides the interior bulbs, I’ve done nothing else electronically. So now, I’ve been having the problem where I’ll come out to use the 4R and it’s completely dead. I’ve replaced the battery and alternator this past Saturday. From Sunday to Wednesday night, I had no issues. It’ll turn over, come to crank it today...completely dead again.

Any ideas what it could be?

if you have a scan guage and leave it plugged in all the time it will drain your battery. Granted i work from home and dont drive very often so its more noticeable for me.

 

[octanejunkie]

Great link [MENTION=69868]LittleCaesar[/MENTION] deffo worth investigating.

Another cause of drain (poor charging) could be increased resistance in wiring, specifically the main POS and NEG battery cables, or an old battery that doesn't want to take a charge anymore.

Are your battery terminals white and chalky? Are the cables making optimal contact at the battery posts?

I thought I was chasing a parasitic drain issue at one point too, but it turned out to be combo of bad battery and resistance in wiring/bad connection at battery. I resolved those and now I leave my BAFX plugged in all the time and no issues with drain or weak starts.

20 year old trucks, lots of issues to consider. Good luck, report back with what you find!

 

[IBallEngineer]

Start with this:
https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

This is a very good link to explain how to check for a draw. Be sure to read some of the questions and the answers at the bottom, could clear up some confusion for you OP.

That said I'm going to tell you what the first rule of electrical trouble shooting is! CHECK THE EASY THINGS FIRST. So I'll give you a short list of EASY THINGS.

1. With the car running, check that the voltage at the battery is around 14V, and then with the car off(battery charged) the voltage should be 12.7 ish.

2. Have the battery tested! I don't care if it's one week old, one day old, or 3 years old, have it tested! New doesn't mean good, it means you just bought it.

3. Look at the battery cables very closely, make sure they aren't dirty or rotten, if they are, fix it!

One more tip that is strictly a 3rd gen thing. My wife's 2000 had a dead battery one day, I started it drove it around and tested the battery, it check out fine. Next day it was dead. I started to test for a draw and I had a big one, when I went to start pulling fused in the Engine Bay fuse block, I noticed a relay was very warm. I pulled that relay and the draw was gone. That was the rear defrost relay and it is controlled by the Body ECU. It grounds the relay when you turn on the switch and in this case was grounding it ALL the time. It's still broken but this is California, we don't need not stinkin' defrosters!

:cheer2:

 

[MStudt]

Here's a good video that I used in the past.

 

[fourwd1]

Don't just check the battery cables at the battery end, check both ends to be sure they are clean and tight.

 

[TheDurk]

This is a very good link to explain how to check for a draw. Be sure to read some of the questions and the answers at the bottom, could clear up some confusion for you OP.

That said I'm going to tell you what the first rule of electrical trouble shooting is! CHECK THE EASY THINGS FIRST. So I'll give you a short list of EASY THINGS.

1. With the car running, check that the voltage at the battery is around 14V, and then with the car off(battery charged) the voltage should be 12.7 ish.

2. Have the battery tested! I don't care if it's one week old, one day old, or 3 years old, have it tested! New doesn't mean good, it means you just bought it.

3. Look at the battery cables very closely, make sure they aren't dirty or rotten, if they are, fix it!

One more tip that is strictly a 3rd gen thing. My wife's 2000 had a dead battery one day, I started it drove it around and tested the battery, it check out fine. Next day it was dead. I started to test for a draw and I had a big one, when I went to start pulling fused in the Engine Bay fuse block, I noticed a relay was very warm. I pulled that relay and the draw was gone. That was the rear defrost relay and it is controlled by the Body ECU. It grounds the relay when you turn on the switch and in this case was grounding it ALL the time. It's still broken but this is California, we don't need not stinkin' defrosters!

:cheer2:

Good points. Another trick is pay very close attention to any relay noise when you connect or disconnect the battery. If everything is off, there should not be any. Have a helper listen inside the cab, too. If a relay is energizing with key off, that is your culprit.

This is no substitute for systematic chasing with a meter, but sometimes it is a faster route to the answer, and it takes zero effort as you are undoing the cable anyway.

 

[19963.4lsr5]

I don't know about Toyota but other vehicles need to have their BCM and PCM go into sleep mode before the current draw can be done.


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[nchacon1984]

Thank you everyone...im going to reference everything you have all mentioned and will start looking for the issue this weekend.

 

[trchandler]

Thank you everyone...im going to reference everything you have all mentioned and will start looking for the issue this weekend.

Did you every get it resolved? I have the same issue now. I've used the multimeter to check all the fuses and relays I could remove. None of them dropped the drain. Can't figure out what to try next.

 

[trchandler]

What's next to find the parasitic draw

Start with this:
How to Find a Parasitic Battery Drain: 11 Steps (with Pictures)

Great resource! Thanks for sharing. I set up the millimeter as described and see I have a 170 milliamp draw. That felt like a step in the right direction. I pulled all the fuses and relays in both fuse boxes, and never saw a drop in the draw. Any suggestions on what to check next?

 

[gamefreakgc]

Do you have any aftermarket gadgets hardwired or plugged into any ports?

 

[spartacus]

Did you every get it resolved? I have the same issue now. I've used the multimeter to check all the fuses and relays I could remove. None of them dropped the drain. Can't figure out what to try next.

May be a bad diode in the alternator. disconnect the power wire from the alternator and check again. Do the same with the starter wire.

 

[19963.4lsr5]

Great resource! Thanks for sharing. I set up the millimeter as described and see I have a 170 milliamp draw. That felt like a step in the right direction. I pulled all the fuses and relays in both fuse boxes, and never saw a drop in the draw. Any suggestions on what to check next?

How long did you let it sit? The ECU needs to be in sleep mode to do the test which means it has to be sitting key off for a while. If you disturbed the power to the ECU hooking up your meter it isn’t in sleep mode.

When I do that draw test (after it’s sat at least an hour) I put one meter cable on the 100a fuse in the under-hood junction box and the other I wedge into the battery clamp. Then I remove the smaller positive cable coming from the under hood junction box

My battery was going half dead just sitting overnight. I did that test and had .025a which was well within spec. Here the 3 or 4 year old battery was toast and interstate gave me a prorated new one.


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[trchandler]

Thanks. I have not been letting it sit for hour first. I will try that. I'll also try hooking up the meter probes the way to recommend. I did have three auto parts stores test the battery and all said it was good. I appreciate the tips. Thanks.

 

[trchandler]

May be a bad diode in the alternator. disconnect the power wire from the alternator and check again. Do the same with the starter wire.

Thanks I'll try that.