Hey Folks! Just got a 2013 Ford E-150, pretty decently used during those past years but both turn signal and brake lights, only on right side are not working. This is what I've checked and it's ok:
- Wiring continuity from the bulb (replaced by a new one) up to close to the internal fuse box. I say close because it's hard to see where the wire goes, what pin it goes to, etc when it goes up and backward to the IP.
- Ground is good. Checked.
- 20A yellow fuse (internal fuse box) is good. Checked.
- Relay? Couldn't find it. Even though all the other turn signal blinks, so I assume it's ok.
Funny thing is the brake light works on the left side - isn't the same circuit for the right side?
I saw a couple of comments about the turn signal key on the steering column, is there something I can check it?

Sorry for so many (dumb) questions, and thanks ahead!

 

All the lights on your van are connected to the BCM module, not a dedicated fuse slot for brake or turn signal lamps. So if you want to check continuity you check from BCM to your right brake lamp. Like you said, the left and right brake lamps should be turned on/off together. So why didn't you check continuity of the left and right brake lamp too? On the brake lamp circuit there won't be a dedicated left and right to your BCM, but there will be a splice somewhere along the brake circuit to split up the left and right, so check the connection at the splice if there is no continuity between left and right brake lamps.
Please also note that almost all ford truck/van use 3157 bulbs on the rear taillight. 3157 is a dual filament, one filament for brake the other for turn signal. If your right brake+turn signal lamps suddenly don't work at the same time, you can remove the left 3157 that is known to work, and insert it into your right side, at the same time, insert the right 3157 to the left, just for diagnostic purpose.
Also note that when all the lights are handled by BCM, even if there is a short circuit on your brake lamp, it might not even blow a fuse, let alone a dedicated fuse for the brake. If you have a capable scanner to retrieve ford specific DTC, you should then see the exact code.
Sorry I don't have any wiring diagram for your 2013, I have up to 2007. If I were you and I do find the diagram I would measure not just continuity but voltage and resistance on the circuit between the BCM and your brake/turn signal lamps.

 

Thanks Heiko!

yes, I’ve checked the right side and both signal indicator and brake lights are working. I’ve swapped bulbs and bulbs+socket and confirmed the right side keeps working and left side keeps not working.

Ive Tracked the wiring up to close to the so called junction box. Continuity is ok.

I’ve checked the voltage and I’ve got something weird . When hazard switch is on, I can see up to 11v approximately for the left side (it’s a digital multimeter and the voltage goes up and down faster than it can process), which makes sense once the left side is working fine. However, for the right side, it doesn’t go farther than 1 or 2v and than goes down.

is it a sign of a short circuit, bitten/smashed/damaged wiring? Or the junction box may need a replacement, or I need to dig in deeper?

thanks

 

On older E/F series those use flasher relay for turn signal, and even another flasher relay to control the hazard light. Your 2013 the blinker/hazard is managed and controlled by BCM. If you want to throw part at your van you replace the BCM, not any junction box.
I wouldn't recommend replacing the BCM at this point since you can try to reset your BCM like disconnecting the battery ground cable for half hour or so, or if you have a capable scanner you can also do a reset, or run active test (before and after a reset) and turn on or off any lamp on demand for 15 seconds duration with a click of a button. Software wise forscan should be able to do active test I suppose. Hardware wise (a physical scanner) Foxwell NT510 Elite **might** be able to do it. On old E/F series when all the lights are not controlled by BCM, then you can't run active test just because the scanner can only communicate with the BCM module, and not a particular lamp itself.
First thing you need to locate your BCM module and test all the wiring. Next thing is to download forscan and run free trial, and of course go amazon and buy the adapter, keep it if you like it. It's better to reset with a scanner/forscan than battery ground disconnect. And most importantly you want to retrieve the ford's specific DTC on BCM. and those codes won't trigger a CEL.

 

As mentioned above these lights are controlled by the Smart Junction Box (SJB). In 2013 it wasn't called a BCM.

Each individual light filament has a separate FET and separate output from the SJB.

See the attached wiring diagram and connector pin out.

It shouldn't be power / fuse as the LR brake light is supplied from the same circuit in the SJB.

I'd pull the C2280D connector from the SJB and apply power to pin 26. If the RR brake light illuminates, it's not a wiring issue and there's something going on in the SJB.

A SJB reset is then certainly in order although the FET may be damaged.

According to Ford, the FETs in the SJB are not serviceable although I've seen videos where the SJB is disassembled and components replaced.