Parasitic Draw 3rd Gen

I'm having my battery die in 2-3 days If don't drive it, tries to start but doesn't (battery still have a decent amount of charge, around 10-11 volts during these moments). once charged the battery tested fine at the local auto parts store. I only drive the truck a couple times a week, but don't think it should be dying in 2 days. I did a parasitic draw test and was reading at like 400ma, I checked all my aftermarket accessories, besides my alpha rex headlights (Remote start was removed completely and the turn on wire for aftermarket amp was disconnected, no change). So I started pulling fuses and when I removed the ECU-B No.3 Fuse that the draw dropped significantly down below 100ma. This was the only fuse that once removed showed any change on the multimeter. But From my understanding that ECU-B No.3 fuse is linked to quite a few things. Can anyone tell me what systems that fuse links to so I can continue to isolate whatever issues is causing the draw? Any diagrams or help regarding similar parasitic draw issues would be much appreciated. (2016 Tacoma Limited 50k miles, Yellow Top Altima Battery about a year or two old)

 

Welcome to the forum. ECU-B 3 goes from the battery to the ECU and then the ECU controls a bunch of stuff as shown on these schematics.

 

Maybe this will help too?
You might have to start unplugging modules.

 

Pretty long list...

1. A-TRAC
2. ABS (Hydraulic Booster Type)
3. ABS (Vacuum Booster Type)
4. Air Conditioning (Automatic)
5. Air Conditioning (Manual)
6. Audio System (Built-in Type Amplifier) (From Sep. 2019 Production)
7. Audio System (Separate Type Amplifier) (From Sep. 2019 Production)
8. Auto LSD (Hydraulic Booster Type)
9. Auto LSD (Vacuum Booster Type)
10. Automatic Glare-Resistant EC Mirror with Compass
11. Automatic Light Control
12. Blind Spot Monitor System
13. Cargo Light
14. Charging
15. Combination Meter
16. Condenser Fan (Automatic Air Conditioning)
17. Condenser Fan (Manual Air Conditioning)
18. Cruise Control (2GR-FKS)
19. Cruise Control (2TR-FE)
20. Door Lock Control
21. Downhill Assist Control
22. Dynamic Radar Cruise Control
23. Electronically Controlled Transmission and A/T Indicator (2GRFKS)
24. Electronically Controlled Transmission and A/T Indicator (2TRFE)
25. Engine Control (2GR-FKS)
26. Engine Control (2TR-FE)
27. Front Fog Light
28. Garage Door Opener
29. Headlight
30. Hill-Start Assist Control
31. Illumination
32. Immobiliser System (w/ Smart Key System)
33. Immobiliser System (w/o Smart Key System)
34. Interior Light
35. Key Reminder (w/o Smart Key System)
36. Lane Departure Alert
37. Light Auto Turn Off System
38. Multi Mode 4WD
39. Multi-Terrain Monitor
40. Multiplex Communication System (CAN) (From Sep. 2019 Production)
41. Navigation System (Built-in Type Amplifier) (From Sep. 2019 Production)
42. Navigation System (Separate Type Amplifier) (From Sep. 2019 Production)
43. Panoramic View Monitor System
44. Parking Assist (Intuitive Parking Assist)
45. Parking Assist (Rear View Monitor) (Built-in Type Amplifier) (From Sep. 2019 Production)
46. Parking Assist (Rear View Monitor) (Separate Type Amplifier) (From Sep. 2019 Production)
47. Power Outlet (120V)
48. Power Window (w/ Jam Protection)
49. Power Window (w/o Jam Protection)
50. Pre-Collision System
51. Rear Differential Lock (4WD)
52. Seat Belt Warning
53. Sliding Roof
54. Smart Key System
55. SRS
56. Starting (w/ Smart Key System)
57. Steering Lock
58. Taillight
59. Theft Deterrent
60. Tire Pressure Warning System
61. TRAC
62. Trailer Towing
63. VSC (Hydraulic Booster Type)
64. VSC (Vacuum Booster Type)
65. Wireless Door Lock Control (w/ Smart Key System)
66. Wireless Door Lock Control (w/o Smart Key System)

Note, some may not apply depending on year and available features.

 

That's almost 1/2 amp, should be easy to narrow down. Just leave the meter in series with the battery and start pulling fuses till it drops, then you found the circuit

 

He did that and found one fuse but there are a lot of things tied to that single fuse.

 

Then just leave the fuse out. attach the meter to it and start unplugging all the crap connected to it. That's the only way to do it. The only shortcut is if there are known issues and you go there first

 

Yes, Op appears to understand what to do based on their post. They wanted a list of what uses that fuse and diagrams.

 

Just FYI:

 

Thanks for the tips! Think I got it figured out. Much appreciated yall

 

Waaaait, what was it!

 

Pulled all the fuses with the ECU-B out like suggested, didn't find anything. Even went a bought a new battery while my yellow top was on the charger, still the same results with new battery (even though yellow top tested fine I was just trying anything and everything). In another desperate attempt to figure out anything I tried reseating harness C29 on the ECU. I read some post about it on here or another forum (cant find it now) that it was linked to ECU-B no.3 in some way and thought maybe it couldn't hurt just to try. After I did that I retested for draw and I was down to 40ma consistently and it stayed like that for more than an hour, so in all honesty not sure what was causing the issue or if its really even fixed, so saying I figured it out is a stretch. Its hasn't been 24hrs since I "fixed" the issue, but no drop in voltage on the battery after sitting overnight and still no excessive draw. Hopefully it continues to stay that way, planning on letting the truck sit until tomorrow afternoon and retesting again to be safe. Will post if anything changes. (Id like to mention during all my testing I made sure to wait awhile after unhooking the battery to do the test, didn't keep the key nearby, and made sure the hood latch sensor and door sensors were disabled so none of the systems would be awake, just to confirm there was no draw from that stuff).