Hello everyone, new member here and seeking some assistance on a problem with a 2006 V6. About six months ago, it developed a parasitic drain (130 ma) which was killing the battery every few days. By process of elimination, I was able to trace the drain to the SJB (passenger foot well fuse panel), but no further.

First, before I was able to isolate the problem as the SJB, I had to take ALL the fuses out of the main, under hood fuse box. After some trial and error, I localized it to fuses 59 and 67 (which are two of the three feeds to the SJB), but the drain only stopped when BOTH fuses were removed. Further, even removing ALL of the fuses and the relay from the SJB had no effect on it; it was present as long as at least one of either fuse 59 or 67 were in place in the main fuse panel.

This leads me to believe that the problem is likely a fault with the SJB module itself since under normal circumstances removing one fuse from the main panel should have stopped the drain, and because the problem doesn't seem to go downstream from the SJB, but rather stops within it.

I've had a good look around and there are no obvious signs of water damage, but I haven't actually removed the SJB module from the car yet, so, questions:

1. Does my hypothesis of the fault being internal to the module make sense?

2. Is this a part which should be sourced only from OEM, or is after-market (if such a thing exists) or junkyard replacement reasonable?

3. Is this a plug & play module, or does it need some sort of initialization to work with the car? I read one article that indicated it came with factory set DTCs which had to be cleared in a specific sequence to "initialize" it.

Any other points, thoughts or words of wisdom much appreciated.

 

Howdy!

Your situation made me go in 'follow rabbit hole mode, so I did. Here we go!

Fuses 59 and 67 are hot at all times, and shown here:
http://iihs.net/fsm/?d=40&f=Power%20...n-SJB.pdf&p=11
In the middle. F59 and F67 go to 'connections' K and J, respectively, in this set of diagrams, which are shown below.

---
F59 to K:
http://iihs.net/fsm/?d=40&f=Power%20...on-SJB.pdf&p=6
This is powering some Low Current Board items, and nothing else:
Various low power lamps.
Shift interlock on the automatics
Heated window (rear defroster?)
Trunk release
And then continues on via 'connections' Y, V and W:

K to Y, V and W:
http://iihs.net/fsm/?d=40&f=Power%20...n-SJB.pdf&p=17
Which you can see are more lights. All the big exterior illuminators.

---
F67 to J:
http://iihs.net/fsm/?d=40&f=Power%20...on-SJB.pdf&p=3
This is powering:
Data Link (F8 SJB)
Instrument Cluster (F8 SJB)
Overhead Console (F10 SJB)
Climate Control (F10 SJB)
More Low Current Board items, all of which appear to be various lamps.

---
Removal of F8 and F10 on the SJB will remove all but the Low Current Board from the equation, and you've done that, so the other items aren't the problem.
The obvious issue you're having is the Low Power Board in the SJB. It's either the board, or one of those things attached to it.
The issue I have is that both F59 and F67 on the BEC (the box in the engine bay) has to be removed to solve the problem. Unless I read that wrong...

Therefore the actual issue is the Low Current Board in the SJB, and the entire SJB has to be swapped out for a good one. As far as I can tell given the description...
Assuming it's not a shorted lamp somewhere... because it totally could be...

To answer your questions directly:
1) Yep, seems to be. But maybe check the lamps/whatever else the Low Current Board runs?
2) You can get after market, ebay, junkyard, etc. Ford might still have them... maybe... it's kinda iffy, last I heard...
3) I understand it's not plug and play unless you miraculously get an *exact* replacement. Aka, the cars are identical in every feature: engine, transmission, axle ratio, power passenger seat or not, etc, ad nauseam. All of it. It'd be better to take it to get it programmed by someone if you can't do that. Read this thread for more info: https://themustangsource.com/forums/...531649/index2/

Finally... it could just be corrosion. Which if it's bad enough on the SJB connectors... but you'd need to take the thing out and see. Maybe a cleaning and some reapplication of dielectric grease before reconnection would fix the problem...

I hope that helps. Electrical gremlins are SO fun... Welcome to the forums!

 

Wow, thanks for the super-detailed reply. I'll start following up on this shortly.

 

Did you ever find the cause of the drain associated with these two fuses: 59 and 67? I have the exact same issue with an 07 Mustang. I took out my interior fuse panel, took it apart, and it looked fine, no corrosion or anything damaged on the circuit board that I could see. There are eight plugs to the interior fuse panel. I unplugged seven of them, leaving only the plug that brings in the hot leads from 59 and 67. I still had the drain. Even with so few circuits connected, I still can't find the drain. I would hate to replace the fuse box only to find out that it wasn't the problem. Thanks - Tom

 

I have the same issue and would love to know if you found the cause.

 

I did not yet solve the problem. Based on a lot of reading, and some more testing, I think it may be as simple as reprogramming the SJB. It can be done at the dealer. I'm going to try a local repair shop first. I think I sourced the problem at the SJB. There are 8 plugs going to it. I unplugged 7 of them, all but the plug with the wires from fuses 59 and 67. With all the other 7 plugs disconnected, I could not get a single component in the car to work. It was as dead as if the battery had been removed. But the battery drain was still there, about 154 milliamps. So I don't know what else could be the problem other than the SJB. I've taken it apart and it looks fine visually, no noticeable corrosion. I've read that if they get wet, then stuff stops working, or causes a battery drain, then will work again after drying out and/or if you get it reprogrammed.

I have a quick disconnect on the battery. Plus it's my wife's car. Plus we hardly go anywhere because of Covid. So I haven't gotten around to seeing if the SJB can be reprogrammed or if that will work. You've reminded me that I should it. I'll do it soon and let you know. Or you can do it and tell me!

Thanks, Tom