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Ask A. Penland Your Own Question
A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6488
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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Found that shaker stereo was draining my battery in my 05

Customer Question

Found that shaker stereo was draining my battery in my 05 mustang
JA: Have you tested the battery with a voltmeter? And can you see if it's leaking or not?
Customer: I did an amp test and its 1.5 amps. When I disconnected fuse 56, it dropped to 0.15
JA: Are you fixing your Mustang yourself? What have you tried so far?
Customer: Yes I am. I discovered that if I completely kill he power to the head unit, I won't lose battery power.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I think that should be enough to get started. Basically what I need to know is whether a new Stereo will fix the issue. As long as the fuse for the stereo is disconnected, the car is fine.
Submitted: 3 months ago.
Category: Ford
Expert:  A. Penland replied 3 months ago.

The radio, which is actually called the ACM (Audio Control Module) is the problem. If you unplug the ACM or remove the fuse and the current draw is gone, then the ACM is the problem. But Fords specs for current draw is 0.05 or lower. Make sure you have the amp unplugged also and check the current draw.

Customer: replied 3 months ago.
What other fuses should I unplug to completely remove the draw from the ACM? I only unplugged fuse #56 under the hood. Vehicle is equipped with Shaker500.
Expert:  A. Penland replied 3 months ago.

Remove fuse 16 in the engine bay fuse box for the amps and see what the amp reading is.

Customer: replied 3 months ago.
Okay. I will have to wait a little while as I have the vehicle running and will need to wait for all draws to settle. Will reply with new reading.
Expert:  A. Penland replied 3 months ago.

No problem. I completely understand. I go through these tests almost every day at work at my dealership.

Customer: replied 3 months ago.
Okay, I removed fuse 16 and amp reading is still at 0.15. When I reinstalled fuse 16, it did not change the amp. At this point, I'm not sure what else could be causing the extra 0.10 amp draw. Any thoughts on other things I could test? By the way, this all started when my passenger floor flooded, due to the drain plug by the firewall getting clogged causing water to come in through the air cabin filter. This caused the stereo and dash cluster lights to stay on after I would exit the vehicle and close the door. I removed the SJB and dried the connectors that were a little wet. I reinstalled the sjb and the electronics work normal on the vehicle again, except for the extra amp draw.
Expert:  A. Penland replied 3 months ago.

Inspect the dash fuse box close to the floor. Make sure no corrosion was caused by the water soaking into the carpet. Check the wiring connectors to the fuse box.

Customer: replied 3 months ago.
Okay I will try that next. I will have to wait until next weekend to get in there again and give the connectors a cleaning. But assuming the current draw was 0.05 without power to the ACM and over 1.0 amps with power to the ACM, would that indicate that I need a new stereo? I would hate to buy a new stereo and still have a high current draw. Thank you again for all of your help. I appreciate it.
Expert:  A. Penland replied 3 months ago.

Yes. Any replacement ACM will have to be programed to the vehicle for it to work. The ACM is a programmable module.