Unusual 0.6 amp Parasitic Draw
 

I have a 2005 Mustang V6 Convertible w/ Pony Package (originally had the Shaker 500 but that's been replaced). Currently when the car is off and at rest it is pulling .14 amps according to my multimeter. I had water intrusion years ago like many others (which I have since mitigated), but it got some water and corrosion on my SBJ at the time.

Steps I have taken to try to fix/diagnose this issue:

• I replaced the battery just in case it was contributing (but did not help).
• I removed all the fuses in the SBJ, but this does not change the draw.
• I replaced the SBJ box, but this did not change the draw.
• I cleaned the corroded contacts on the connector plugs to the best of my ability (but had no impact)
• There do not appear to be any shorted lights staying on in the trunk, car, or glove compartment.
• I tested the alternator (both the Red B+ line and the 3-pin connector) did not impact the draw.
• Disconnected the amplifiers to see if they were staying powered due to the corrosion but they are not.

My next idea is replacing the wiring harnesses that had some corrosion with new ones and check my new radio. The Ford Job Aid for “Parasitic Battery Drain" suggested minor corrosion on connectors could cause a parasitic draw. It's a bit expensive and I'd rather not waste money if that's probably not the problem.

Based on my symptoms and the diagnostic attempts I listed above does anyone have a suggestion of what else I should try to either diagnose or fix this issue?

Welcome,

It Seems The Drain Issue is Never Ending and Many Threads Have Been Done on Them and it Sounds Like You Have Covered a Lot of Bases.

Check Out This Post For Some Alternator Perspective!

https://themustangsource.com/forums/...7/#post7093111

Also For Some Chasing an Electrical Gremlin I Would Watch These Vids!

https://themustangsource.com/forums/...issues-551265/

KC

welcome to the forum

The only way I know to isolate the source of a current draw, is to remove fuses one at a time, while measuring the draw, to see when the draw stops -- then you have at least narrowed it down to one circuit

So I misdiagnosed the draw's amount. The draw is actually only .14 amp (I forgot to put a screwdriver in the door latch while I was working so the vehicle was staying in awake mode). :doh: I'm going to update my original post accordingly. With that realization:

• I re-tested all the fuses while vehicle was asleep and none of them had any impact on the draw.
• I also tested the alternator diode and 3-pin connector, no issue with the alternator.

I need to see if my aftermarket radio is pulling power while off (it's not supposed to but who knows). Any other ideas you all can recommend for a draw that doesn't seem to be impacted by any fuses? I feel like if it was corrosion on wiring after the SJB then pulling fuses would de-power those lines and drop the draw.

Parasitic draw - Check your starter
 

Hi.

This problem plagues most early S197s.

Two years ago I got fed up and restarted the pain staking process of tracing every wire, ground and components. I had swapped my radio and SJB a few years prior.

What I finally found was my starter was pulling about the same draw as you found.

I tried swapping out the wires and the same thing. I then ended up changing the starter.

So far 2 years and no issues. 🤞

I hope this helps.

Stumbled on This & Watched It! Seems Like a Good Way To Search For The Issue!

Anyhoo, Hope It Helps!

KC

I can relate. I had my 2006 for 15 years and put eight batteries in her. Some of those, at least, were replaced under warranty by the dealer. But it was a nuisance.