Parasitic battery drain on a 1992 toyota 4runner, my Runner has the 3.4 swap. I am having a battery drain issue if the vehicle is left parked more than a few days the battery is significantly depleted. I am not electrical savvy so I'm running off youtube. Set multi meter up for 10amp. and removed negative battery cable and checked for a battery draw. I am getting .28 on my meter. When I pull the efi fuze I drop out to 0. Is there anyone here who has experience with this?? So where do I go from here as a process of elimination to get it fixed. I have a new battery and alternator installed prior to this issue being found.

thanks everyone

 

The fact that the drain drops to zero when you pull the EFI doesn't indicate the fuse is bad. It shows the drain is in that circuit someplace. NOW, you need to track down just where in the EFI circuit the drain is. Follow the circuit down, and remove the various parts connected to it, one at a time, until the drain vanishes. Problem is, you need to keep the rest of the parts in, because you need your meter to keep telling you whether the drain is still there of not. When you find the right part, it will show up on the meter as no draw on the battery, or minimal draw, anyway. If you haven't found the right part, it will show draw when you remove a part. Like say you remove the alternator. Still have the draw: alternator is good. Put it back into the circuit. Next, you remove a headlight. OH! The draw vanishes! That headlight is the problem.
You need a good schematic so you can track down what all parts are in the circuit, and all the circuits that branch off of them.
If you want to continue to use the truck while trouble shooting, pull the negative lead off the battery, or the EFI fuse. Put it back when you want to drive.

Good luck, and let us know what you find.
Pat☺

 

"Follow the circuit down" is generally the correct advice, but may be difficult with an engine swap. Who knows what else was modified?

Assuming a more-or-less standard installation, the EFI fuse (sometimes referred to as MFI in Toyota documentation) https://web.archive.org/web/20120417.../2powersou.pdf feeds the "keep alive" BAT pin on the ECU, and the EFI relay. So pull the EFI relay and see if that changes your draw. If it does, then the relay (or the socket or wiring ...) has failed closed and is the cause of the draw.

If that doesn't work, and the BAT pin of the ECU is the source of your 280ma drain, that will be a bigger problem.

 

what I do know about the fuel side (electrically) that is altered with this swap, is that there is only 1 O2 Sensor that had been installed upstream of the Cat, so I have been getting an O2 sensor code for O2 Sensor Bank 1 & 2. I installed brand new O2 Sensor too though, codes have never left, so I assumed that would be due to the lack of a second 02 sensor not being there? I also don't know if I may have a bad MAF, at one time I got a MAF code, pulled and cleaned it and the code didn't come back is that tied together with the EFI Fuse? since June, I have had a few misfires/hard starts since I got the swap back in june, and thought maybe dirty fuel as the vehicle sat for 5 years with a dry tank and old fuel in the lines maybe when the guy dumped fuel into start the rig it sucked in some debri and gunk and plugged up some injectors? I replaced the fuel filter the other day when I did my oil it looked like crap, ran a quart of MMO through the crankcase 500 miles before the oil change, ran a can of Berryman's Chemtool B12 through a tank of fuel and have added 4 oz of MMO to the fuel after that to every fill up. just some extra TLC to it. I just put in a new battery and alternator the other day.

 

[QUOTE=scope103;52492058]"Follow the circuit down" is generally the correct advice, but may be difficult with an engine swap. Who knows what else was modified?

Assuming a more-or-less standard installation, the EFI fuse (sometimes referred to as MFI in Toyota documentation) https://web.archive.org/web/20120417.../2powersou.pdf feeds the "keep alive" BAT pin on the ECU, and the EFI relay. So pull the EFI relay and see if that changes your draw. If it does, then the relay (or the socket or wiring ...) has failed closed and is the cause of the draw.

If that doesn't work, and the BAT pin of the ECU is the source of your 280ma drain, that will be a bigger problem.[/QUOTE

So I hooked my diagnostic scanner up and here are the codes thrown

P1600 (stored) 1.Ecm Batt malfunction 2.EEP-ROM Read or write error.

P0100 (stored) MASS or Volume Air Flow Circuit.

P0135 (pending) Oxygen Sensor Heater Circuit (Bank 1 Sensor 1)

PO141 (pending) Oxygen Sensor Heater Circuit (Bank 1 Sensor 2)
What does anyone make of this? Did the dude install my wiring harness wrong during the 3.4 swap?