Ford Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #1
Hi All, just wondering if anyone has had any luck repairing a smart junction box(SJB)? We have a 2004 Freestar (3.9) that has some issues, including 1 with the power door locks, that point to the problem being with the SJB. We've spent some time trying to find a short or some other problem with the power door lock wiring without any luck. Since the problem is with all the power door locks it appears that the culprit might be with the relays that are embedded into the SJB. Why Ford would design the SJB so that we couldn't remove/replace relays is beyond me but it is what it is. Getting a SJB from the junkyard is iffy since the junkyard unit may be defective as well. So I am hoping that someone here has some advice on how to test and repair the smart junction box. Any and all advice is welcome! :)))

Also, what is the latest advice on how to handle/fix the instrument cluster lights (too dim)? We can't see any of the digital readouts unless it is at night, and even that is hard when we have the headlights on. I have read other posts where this is a common issue so I am hoping someone here could point me in the direction of a fix.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #3
Thanks for the help. Any advice on which door might be the probable source? (ie: Is any door more likely than the others to have this problem that I should check first)? Also, does replacing the OEM Instrument panel interior lighting dimmer switch usually take care of the dim odometer readout problem? On our F150 there is a cold solder joint that can break free and cause a similar problem.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #5
Thanks for the advice on the drivers door to be the 1st place to look, do you happen to know what color wires I should be looking for (that control the door locks)? Also, as far as the dimmer switch, isn't is just a variable resistor/rheostat? If so, then if I just unplugged it and put the wires together to just bypass the switch, wouldn't/shouldn't the odometer readout come on bright? That would be the easiest solution in the short term or am I missing something? (Of course at my age, I am probably forgetting something). I did see a you-tube video where the guy said there were some resistors on the back of the instrument cluster that cause this problem. I know our F150 odometer has that same problem (cold solder joints breaking and causing the odometer readout to go off and on or fade out). Thoughts?

Once again, thank you for your help with this, I do appreciate it!
 

·
Super Moderator
Joined
·
19,788 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #8
Hi All, and thanks for the SJB electrical diagrams. Not being too familiar with electrical schematics, I can't get as much information out of them as those who use them all the time. However, they are very helpful in letting me know what is controlled by the SJB so I can troubleshoot our problems with the the power door locks and the too dim to read odometer (during the day). Having the base model Freestar, we don't have the rear control panel or the message center on our display, but it does show me that the power door locks appear to be linked to the power windows. (JPEG 1 of 4-Master Window/Door lock-unlock switch). So my thinking is if the windows all work OK, then my problem with the door locks not locking is probably more related to a broken wire?? Or am I missing something The doors will unlock with the remote, but won't lock at all whether or not we use the remote, or if we use the buttons on the doors. (although my wife says every once in a while they do lock using the door button but I have not seen this myself). A replacement dimmer switch is over 40 bucks on ebay so if by-passing the switch fixes the too dim to read odometer, then I might just do a permanent bypass.

Any thoughts or advice?
 

·
Registered
Joined
·
22 Posts
Discussion Starter #10
So far, I haven't been able to find any trouble with the wiring but that doesn't mean there isn't a broken wire where the sheath(wire covering) isn't broken so that I could see the break. Is there a way to test the locks, other than using the remote or the door buttons? By that I mean, is there a key/on key off sequence that can be used to verify the signal is getting to the locks? That might eliminate the chance of the problem being a broken wire? If there is a way, maybe it would help me determine if the trouble is the smart junction box or the locks. Other than that method, is there another way to force the locks to lock or unlock?. Perhaps with the lock diagram if I knew what wires to cross together I could rig a temporary switch to help isolate the trouble. Of course, with my old eyes, it might be difficult to see what the wire color code is and totally understanding a schematic is still something I need to master.

In any event, any and all advice is welcome!
 

·
Super Moderator
Joined
·
11,057 Posts
On the drivers door switch, ground the dark blue/light green wire for unlock and the white/violet for lock. Make sure 30amp.fuse 1 is okay. Do you have any friends that understand wiring diagrams?
 

·
Registered
Joined
·
22 Posts
Discussion Starter #12
I can ask my son to come over and look at it. Is the 30 amp fuse under the dash somewhere, or under the hood?
 

·
Super Moderator
Joined
·
11,057 Posts
I should have said fuse 60, the wiring diagram shows 1.60 meaning fuse box 1, which is under the hood and #60 fuse in that box. I missed putting the fuse number after the box number. Sorry about that.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #14
Thanks everybody! I have a day tomorrow when I can devote all my time to this and I will use everyone's advice to try and locate the problem(s). I'm a good bit slower than I used to be (many, many years ago) but I am really curious as to what is the cause of the trouble.
 

·
Registered
Joined
·
2 Posts
Good afternoon Everyone, Name is Justin

I have a 2008 Ford Mustang. My issue is the AC CONTROL HEAD has no power. Bought a new AC CONTROL HEAD, that wasn't the issue. I had water coming in on the driver side floor board for a long time. Was able to fix that problem after weeks of looking and research. I wanted to ask could the Junction BOX be the issue as to why my AC isn't coming on? I took it to a AC SHOP and they told me control head first bought that it wasn't the issue and he thought the only thing it could be was the Junction box? I have started looking at prices and is very expensive. If I buy a new box can it go directly into car or does a professional have to install it? Are there any way to look and see if the JUNCTION BOX is the issue. I have checked every fuse and there is some corrosion but all fuses are good. I need some help with this as I am at whits end on what to do next.

Thanks
Justin
 

·
Super Moderator
Joined
·
7,984 Posts
The smart junction box is what sends power tot he clutch for the AC compressor. Did you check that fuse F14 is not blown and that power exists there?
 
1 - 16 of 16 Posts
Top