Significant Fuse #5 parasitic draw?

MBIVER

MEMBER
2014 FORD MUSTANG
3.7L
V6
2WD
AUTOMATIC
121,000 MILES

I have a parasitic drain that drains my battery within 24 to 30 hours.
I used the following procedures to check fuse draw -

1) Turn off car, open car doors and wait until lights turn off by themselves.
2) Disconnect Neg Battery cable.
3) Set Multimeter to read Amps (10AmpMax).
4) Connect red lead to Neg Battery cable.
5) Touch Black lead to Neg Battery Terminal for 3-5 seconds to obtain reading.

Initial reading right after car is asleep is about 6.2 Amps
Next morning reading was about 1.08 Amps (but battery was drained a lot.

80Amp fuse in the engine compartment pulled and Amp draw is negligible, telling me it is definitely a passenger compartment issue.
With the 80Amp engine compartment fuse installed, I proceeded to check the interior fuses.
I noted the following:
Console, interior, headlights all flicker whenever I check anything - so I removed it, and it drops by about.4 Amps.

BTSI (Fuse #5) is biggest drain - 5 Amps.
Radio.2 Amp draw.
SYNC.2 Amp draw.

I have an aftermarket stereo - just installed.

Son drives the car about 1 mile each way to work, longer drives only about once per week.

No issues with car getting stuck in park or anything to suggest a problem with the Brake Transmission Shift Interlock (BTSI) but that seems to be the biggest problem.

Next step is to reinstall OEM radio and check radio and SYNC draw from that. If similar, might just leave SYNC fuse out. I don't think I need it with new radio.

Currently leaving on charger every night.

Any suggestions?

2 Replies

MBIVER

MEMBER
2 POSTS

Also- Alternator replaced Aug '22. Battery replaced Jan '23.

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Wednesday, March 1st, 2023 AT 9:10 AM

STEVE W.

MECHANIC
13,467 POSTS

Leave the meter connected and see where it sets. Leave the doors open but use a screwdriver to trip the door latches closed, there are switches in the latches that will keep activating the security module if the doors are simply left open with the latches open. The act of disconnecting the meter and the 2-3 seconds of the initial connection is enough to wake modules. The 6 amps is likely a module waking up as soon as it sees power.
What you need is the number once all the modules are off.
https://www.youtube.com/watch?v=6xFo_oHFF48

I show fuse 5 in the under-hood box as a power point socket fuse 5 in the smart box on the right kick panel as a module that does more than just the shift interlock. Wouldn't surprise me if it was a bad SJB. However, I would disconnect the radio as well if this started after it was installed.

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