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brake light / turn signal light Diagram


Tike

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can someone share a wiring schematic for the taillight wiring. i am getting rear right bulb out message tried new bulbs new socket testing power but my trailer brakes and signals work fine... does the trailer harness splice off the turn signals or have a homerun to SJB....?
08 ST xlt job 1
 


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bdmaash

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the trailer lights have their own fuses (left, right << wrong, its one fuse), won't be home for a few hours to check. I would think that SJB would only check lightbulbs on the truck.
It is a current draw test, so a broken power or ground wire at/to bulb in addition to failed bulb will trigger bulb out.


 
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bdmaash

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Tike

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THANKS bdmaash!!!! been digging through every explorer and ford forum on the web to find this.

Questions - what is "HSD" inside the SJB and
what are C0532, C405, C4001 (dotted lines labeled 5, 5,6) ? is there another device in-line here?
is HSD the 'sensing' device? -- it appears the front and rear turn signal on the right are both coming out of the HSD. i am going to check the front right bulb -even thought its working- maybe there's an issue with that causing a load/ line resistance issue for the sensing device?

SJBs are so stupid.
 




J_C

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If the diagram is correct then yes the HSD has to incorporate the sensing circuit.

The Cxxx numbers designate connectors, presumably this one diagram covers multiple vehicle years and/or options packages and the connector wiring could change, though assuming the colors are correct is the place to start.

Have you visually checked the right rear bulb to see if it works, as a turn signal or brake lamp?

The typical way to test this is use a multimeter on that VT-OG wire coming out of the HSD to see if it has 12V on it when the bulb should be lit. Backprobe the connector or check on the HSD contact, obviously you can't unplug the connector from the HSD and check on the wire side going to the bulb. Since the front right bulb is working, make sure you are getting 12V on that YE-VT wire as a sanity check.

if you are getting 12V out for the right front (relative to chassis ground) but not the right back, it looks like your HSD has a problem. In prior generations a common problem with bulb sensing circuits was the resistor the current passes through would get hot and over time, break the solder joint or delaminate the copper trace off the PCB, and could often be repaired if you have fair soldering skills.

If you are getting 12V out to the right rear lamp, check resistance between the wire harness connector to the HSD (VT-OG wire), and the bulb socket positive contact. It should be pretty near 0 ohms and the light does not have to (supposedly) be on for this test, unlike the others.
 




Tike

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Thanks - cxxx is the harness clip into the SJB then.
is HSD and acronym... or replaceable :D?
i was talking to someone on the sport trac forum about this too and forgot to post what i have done here.

i am not getting power at the rear right turn/brake socket. so i opened up the drive side kick panel and found the violet/orange wire(rear-right) and and the grey/brown wire (rear-left) and checked voltage with the Multi-function switch in neutral and they both had like ~.03V then turned on the left and get alternating 12V,6V,0V (guessing my multi-meter cant update fast enough) then tried the right and there is Voltage fluctuation but it appears random and max 3V. the

i am going to take a look at the front bulb/directional. if it shares the HSD there is a chance that could be causing the issue. might snip the violet-orange wire at the kick panel as its right next to the SJB and alligator clip to a bulb and bulb to ground to test. i also have forscan i just haven't had time to learn it or use it (if it would even make a difference). worst case i will probably buy a 4 pin trailer harness for dirt cheap and wire that in or something to at least be legal and pass inspection.
 




J_C

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There is no need to snip the wire to just do a bulb test. You can hook a multimeter positive probe to it and the negative probe to chassis ground to check for 12V, but from what you wrote you already did that?

If you'll pass inspection with the bulb out display still showing, but the bulb working, then you can just wire the GY-YE wire from the MFS (multi function switch) to the VT-OG wire. I mean both these wires should be accessible at the SJB connector, you don't have to do a jumper wire run all the way from the MFS.

If the right front bulb works this indicates your MFS works, and power is getting to the SJB, so based on the above, all that remains is power isn't getting OUT of the SJB to the right rear, correct?

If all this is true, I would open the SJB and inspect the solder joints if you have a soldering iron, or even if you don't, you can measure at the resistors it presumably uses to measure current to determine the bulb circuit is working or not. Having the varying voltage but that stays low, is a fair indication of a bad solder joint.

It would not surprise me if you took the bulb out and then measured the voltage, it would be closer to 12V (instead of 3V), like the other side since it then has no load on it. A bad solder joint (or connector corrosion or wire frayed almost in two) can cause a voltage drop under load.
 
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Tike

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yeah i did that, i wasn't sure if the SJB cuts power to the bulb after it sense an issue in the circuit. wonder if a grounding issue caused the solder to go bad...

yes - testing the VT-OG wire showed no power out.(rear socket or kick panel) the SJB is only a few years old as i blew one up before by accident. and it was 550 ish to replace. wish i asked for that back...

ever open the SJB? seem to remember its under the driver dash but there is also another little box control unit thing there. cant image its more than 20 minutes to replace with a new one and about $250 for the new sjb. but id feel unconformable trying to program it with forscan...
so if i go the solder route how do you open these "sealed units" it looks like its just a few clips, maybe heat gun if theres adhesive?
 




J_C

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yeah i did that, i wasn't sure if the SJB cuts power to the bulb after it sense an issue in the circuit. wonder if a grounding issue caused the solder to go bad...
No, it just measures current flowing through the circuit and triggers to display the warming message if the current is lower than expected by comparing a voltage drop across a resistor for each bulb monitored. It does not have the capability of cutting power by design, would only lose power output from an internal fault (as long as it has power input and the MFS or headlight, etc, triggering it).

No, a grounding issue could easily cause the bulb not to light, and could cause the circuit to display the message, but could not cause the solder to go bad.

yes - testing the VT-OG wire showed no power out.(rear socket or kick panel) the SJB is only a few years old as i blew one up before by accident. and it was 550 ish to replace. wish i asked for that back...
Absolutely, ALWAYS ask for high priced modules back. It is a common repair scam to claim one has failed then they sneakily repair the real fault instead and never tell you about that.

ever open the SJB? seem to remember its under the driver dash but there is also another little box control unit thing there. cant image its more than 20 minutes to replace with a new one and about $250 for the new sjb. but id feel unconformable trying to program it with forscan...
so if i go the solder route how do you open these "sealed units" it looks like its just a few clips, maybe heat gun if theres adhesive?
One step at a time. AFAIK it is behind the radio, next to the glove box. You should access it anyway to make sure that power is coming out on the pin going to the VT-OG wire, AT the SJB to be sure there is no fault at that point. After that point a wiring fault could cause it so you want to find the first point in the circuit that power fails.

It should be fairly simple to remove and examine it to determine if it has more than clips or fasteners holding it together. In the past Ford has not used adhesives that needed a heat gun, but with each passing model year, it wouldn't surprise me, but for now I would assume it is just plastic tabs or fasteners. If plastic tabs, remember they are old and will be less prone to crack apart if in a warm environment.

I do see plastic friction-lock type tabs on the perimeter of the SJB you pictured. Odds are you just need a small flat blade screwdriver, some finesse, and for it not to be cold during prying. It could help to have a spare credit card or whatever to wedge in as you work your away around the seam popping it open.

I like to point a hair dryer at old plastics to soften them first, but being an interior part, even if there are clips holding it together that break, duct tape or whatever would be fine to hold it back together after an examination. It's not like it needs to be sealed in an interior cabin location.

If it's just a bad solder joint there is no need to buy a new one. That is easily repairable as good or better than new. AFAIK, you cannot program it with Forscan which is only used to toggle established values in existing programming. I could be wrong, never tried that. Regardless if you pulled one from an equivalent vehicle at a junkyard it probably wouldn't need programmed.

There's no way I'd pay hundreds just to resolve a bulb out issue. Even the text display of the error condition should be possible to hack away with the existing module. If it's like the last generation bulb out monitor circuit, it just required severing a signal line on the PCB with an x-acto knife.
 
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Tike

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will having the SJB unplugged for a few hours cause any issues or need for reprogramming?

really its in passenger dash? i think this is a labeling error, i thought it was the under the driver dash by E-brake - housing the fuses -and that's where i see the harness running into and matches the photo i posted above... Ford (8L2Z-15604-B)
there appear to be different models of SJB too. variations -- 8L2Z-15604-A 8L2Z-15604-B 8L2Z-15604-C 8L2Z-15604-D
i have a diagram below and it has 2 SJBs....

only other thing i could think of that might have caused this - i had LED side-view turn signals spliced into the turn signal lines for over year with but had no issues so im guessing that wasnt the issue either. i removed them last week when trying to trouble shoot this anyway.

Explorer Sport Trac 4WD V8-4.6L VIN 8 (2007)



View attachment 175992
 




J_C

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I don't know that diagram, whether it is correct or not. It easily could be, if you find it there then that is settled. It will not cause a problem to have it unplugged for hours, days, weeks, etc.

The part # variance happens with many ford parts. The important string in the part # is probably 15604.

LED turn signals would only "potentially" cause a lamp out warning if they replace an incandescent bulb monitored by the SJB. They have no effect on monitoring any other bulb, UNLESS that other bulb had the same power source and the wiring came apart and shorted, blew a fuse or is still shorted, but that does not seem to be what is happening.

You seem to be weaving around instead of following my suggestions. That's fine but that is the only thing I can recommend, to first test and find the fault.

You'll know you have the right box because when you unplug the connector to it, ALL the bulbs it senses will cease to work, and if the wire colors match up that is another indication.
 




bdmaash

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just saw the followups
good suggestions
I think J_C's suggestion of a short on the added led side marker wiring is still plausible, but more open/almost open circuit where it was spliced, and would be my first check.
Tike, would you be able to take some pics of SJB, (internal, mounted...) I want to modify the one in my truck to eliminate the "LED" bulb out warning (lower the current setting)

(edit) I've always thought the SJB was part of the fuse box - under dash at the parking brake, maybe the "HSD" high side detect - my interpretation is in that box pictured, < that is the part that needs to be modified for LED bulbs

thanks
 




Tike

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just saw the followups
good suggestions
I think J_C's suggestion of a short on the added led side marker wiring is still plausible, but more open/almost open circuit where it was spliced, and would be my first check.
Tike, would you be able to take some pics of SJB, (internal, mounted...) I want to modify the one in my truck to eliminate the "LED" bulb out warning (lower the current setting)

(edit) I've always thought the SJB was part of the fuse box - under dash at the parking brake, maybe the "HSD" high side detect - my interpretation is in that box pictured, < that is the part that needs to be modified for LED bulbs

thanks
i remove all spliced in wires two weeks ago from the VT-OG and the left rear brake/turn wire aswell.


il grab some phots now. i have the truck apart now. give me a few minutes....

interesting enough.... i used forscan for the first time today and pulled all the DTCs and saw fault B106E....
B106e Ford Description When a repetitive fault causing a circuit overload is detected on certain output circuits, the Smart Junction Box (SJB) disables the circuit by removing voltage, or ground, to the affected circuit. The circuit remains disabled until the fault is corrected and an on-demand self-test is run. When the on-demand self-test has been run after all faults have been corrected, any DTCs related to the fault are cleared. Read more: B106e Ford - Solid State Driver Disabled Due To Short Circuit

--- SJB can stop power going to a location with the issue then...

then i took off the front headlights and saw the blinker and marker bulb are all charred up with damaged bulb but still functional. - replacing those bulbs tonight for sanity sake.
 




Tike

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J_C

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It is hard to get a good idea of working room and orientation from someone else's pictures under a dash.

I would try to pull the SJB out and see how much slack you have on the wiring harness/plug for the lights, probably not easy to measure wires there or jumper from SJB 12V input to the output for the faulty light as a test.

I would still try opening the SJB and look at the large resistors inside for faulty solder joints. Another option is put a jumper wire from any 12V source (like direct to the battery but you should put a few amps, say 5A fuse on it) to the VT-OG wire, with the connector unplugged from the SJB.

Otherwise I would seek availability and price of a SJB for same generation Sport Trac (or first pull the SJB to get the part # and research online which vehicles (such as a regular Explorer) and model years used the same box. As far as programming it, do you know if there is anything more needed than to get it to work with your key transponder chips and remotes? I imagine the remotes can be programmed in yourself with nothing more than a couple working keys (see the owner's manual) and the keys themselves, probably the full version of forscan app on a windows device can program in the keys.

I'd still open the SJB and look for bad solder joints. If you were going to replace it anyway, then you don't have much to lose but if you were to jumper to the VT-OG wire first to see if the bulb lights, then at least you'd know the wiring from that point back to the bulb is working.

Sideways diagrams give me a headache so here it is again rotated.

sjb.png
 




Tike

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dug this up from forscan forum posting for everyone.

"After a long day my turn signals and 4 way flashers quit working! I didn't know that on these particular vehicles, there is no flasher can! The flashers are controlled by the GEM/SJB!
To replace this devil of a device, its not all that hard but, you will spend a lot of time on your back!
It is located directly behind the dash above the parking break and is the fuse box assembly!
First you need to access and save the data in your current GEM/SJB. FORScan does a great job at this and is a invaluable tool!
Disconnect your battery!!
According to Ford, you will need to remove the Parking brake assembly and the hood latch. This isn't necessary to remove the SJB but it is necessary to reinstall it!
Once you have scratched your knuckles to remove the wiring connectors and the three screws holding it in, it comes right out.
The three screws are strangely located. 2 screws are located behind the headlight switch. Simply remove the dress panel on the left side of the dash and push toward the rear on the top of the light switch assembly. Once the switch comes out, you can clearly see one of the bottom screws. The top screw is hidden behind the wiring harness. The other screw is located behind the firewall and just top of the fuses! Remove all the connectors(I used two long screwdrivers), and out it comes.
To install the new one, connect the wires first! If you removed the parking brake assembly and everything else, it should be easier to hook up the wires.
The first screw you should put in is the one from the back side. Then put the two from the front in! Trust me on this, that back screw doesn't want to line up any other way!!

Once you have cleaned up all the blood from getting attacked by the sharp edges, upload the data back you your GEM/SJB and all should work!!
Best of luck and keep trying!"
 




bdmaash

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photo's didn't work (may be in a non-shared folder)

Don't think there is anything wrong with the SJB since it is shutting down the output to protect the system from the short (over current condition).

but yes - read out module data with forscan if replacing with a different one
 




Tike

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photo's didn't work (may be in a non-shared folder)

Don't think there is anything wrong with the SJB since it is shutting down the output to protect the system from the short (over current condition).

but yes - read out module data with forscan if replacing with a different one
i have not tried the procedure to cleat that dtc keeping the sjb in that state. the only way to get power back is to clear all dtcs then run a self test. i wonder if i was grounding out in the LED wire that a spliced on- it triggered this safe mode state and then i remove the wire but never did this procedure. more testing ensues thursday when i am off. til then riding the KLR in the cold!

Normal Operation The Smart Junction Box (SJB) - controls the output of several vehicle systems by means of solid state drivers. A DTC sets when an overload occurs on any of these drivers. The module also tracks the number of repetitive faults on each of these circuits, and then it compares said number of overloads to 3 progressive thresholds established for each circuit. If the third threshold has not been met, the DTC for the affected circuit can be cleared by eliminating the fault, clearing the DTCs and then running a self-test. At the point that each of the first 2 thresholds is met, DTC B106E sets along with a DTC related to the affected circuit. Once the final (third) threshold has been met, the affected output is permanently disabled, and DTC B106F sets, at which time the SJB must be replaced. • DTC B106E (Solid State Driver Disabled Due to Short Circuit) — a continuous DTC that sets when the SJB has disabled an output circuit due to a repetitive fault that overloads said circuit. A corresponding DTC for the circuit in question is also set. • DTC B106F (Module Disabled Due to External Fault) — a continuous DTC that sets when the SJB has permanently disabled one or more output functions due to a repetitive circuit overload. DTC B1342 also sets at this time. When DTC B1342 is set because the module has reached a third threshold and the SJB has permanently disabled an output, no DTCs can be cleared from the SJB. Using the module self-test to confirm a repair is not possible and a measurement using a digital multimeter of the affected output circuit is required to make sure the fault condition no longer exists.

also regardless of whether i figured this - the amount of research on these SJBs was pretty limited on the forum - so we are giving people future information all in one place, at least!
 






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