Well I'm stumped (electrical).

[OFC Ranger]

I think you have to break this down into buckets to diagnose.

This get's convoluted trying to type out the scenario, but here's the ole college try.

You have two circuits, left and right, with four current draw sources.

1. Left stock light housing
2. Left after-market signal
3. Right stock light housing
4. Right after-market signal

With everything stock you get a hyper-flash which points to the BCM interpreting the circuit as being under drawn on current, ie. bad bulb or replacement bulb drawing less current than expected.

In one setup the after-market signal does not function but if you swap to the other it functions as expected but you still get hyper-flash in both scenarios.

It's possible that the after-market signal went into thermal runaway damaging a circuit on the BCM resulting in a loss of its ability to read the current on the line and enough damage was done that now it puts out less current than the other side. There is enough current available for the stock LED but not with the addition of the after market signal. The after-market signal may (most likely) have a higher current draw demand than the stock light housing.

Yeah that makes sense I got a few things I can try before I just will assume that that's happening and leave the signals disengage for now and just deal with the hyper blink.

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[OFC Ranger]

Well some good news. Sort of...

Still have aftermarket turn signals disconnected, but yesterday my hyper flash went away for a trip across town. Sadly on the way back I stopped for gas and upon restart it returned. So that means there is hope yet.

On my next set of days off I am going to move to the engine bay to troubleshoot. This is the only other location I tampered with to splice in turn signals on the aftermarket grille I previously had installed. I am going to delete those splices and see what happens.

I will catch this gremlin dammit and when I do I am going to smash his shit like the hammer of God.

Why I am here, are there any bulbs that share the turn signal line besides the obvious ones? My rear lights are LED, but everything up front is still halogen. Currently all obvious bulbs still work fine.

 

[JDowns]

You mentioned you have stock LED lights in the rear???

Keep in mind that LED's will have different current draws based on temperature.

At cooler temperatures LED's will draw less current, but as things warm up they will draw more current. This is why constant current drivers are used to prevent thermal runaway and for high lumen applications heatsinks are required to lower junction temperatures.

This is a common issue for folks who replace halogen with LED and get differing results from region to region and from season to season. You may find a drop in LED without a constant current driver works just fine in the winter months but come summer all of a sudden you have an issue.

 

[cfhgarza]

Did you by any chance install Lariat headlights and change the settings in Forscan?

I was having a similar issue, Hyper flashing but all turn signals worked. Turns out the brake lights were going out intermittently. The cause was I loaded the incorrect settings when making the Lariat lights work causing some sort of a BCM fault.

Check to make sure your brake lights are working.

 

[OFC Ranger]

You mentioned you have stock LED lights in the rear???

Keep in mind that LED's will have different current draws based on temperature.

At cooler temperatures LED's will draw less current, but as things warm up they will draw more current. This is why constant current drivers are used to prevent thermal runaway and for high lumen applications heatsinks are required to lower junction temperatures.

This is a common issue for folks who replace halogen with LED and get differing results from region to region and from season to season. You may find a drop in LED without a constant current driver works just fine in the winter months but come summer all of a sudden you have an issue.

Unfortunately previous use has been across all weather spectrums when they were working can you think of anything I can add in the line between the signals on my rack and the factory tail lights to help reduce this possibility?

It's still bizarre that I can swap over right to left connections and it works fine but at this point I have nothing better to do and start checking off the more meticulous things.

 

[OFC Ranger]

Did you by any chance install Lariat headlights and change the settings in Forscan?

I was having a similar issue, Hyper flashing but all turn signals worked. Turns out the brake lights were going out intermittently. The cause was I loaded the incorrect settings when making the Lariat lights work causing some sort of a BCM fault.

Check to make sure your brake lights are working.

No I have not and I don't use forscan.

 

[JDowns]

Unfortunately previous use has been across all weather spectrums when they were working can you think of anything I can add in the line between the signals on my rack and the factory tail lights to help reduce this possibility?

If you don't know the current rating of the fixture then you'll need to use a multimeter or other piece of equipment to test the amp draw. Once you know the amp draw then you just need to size the appropriate size constant current driver. All sorts of companies make constant current drivers, LuxDrive has been my goto when I need one (buck-block, buck-tooth, etc). If you undersize it will act like a dimmer and slightly oversized will give you a bit of lee-way.

You would want them in between your non OEM add-on and your splice.

It's still bizarre that I can swap over right to left connections and it works fine but at this point I have nothing better to do and start checking off the more meticulous things.

The fact you can switch just isolates the problematic circuit to that one side.

The BCM has individual circuits for each of the four corners and each of the individual circuits. Example you short the front right marker, everything else but that marker works. Reset the BCM and that front right marker works again.

If you go down the rabbit hole of searching for the issue then it has to be associated with one of the turn signal circuits, hence the hyper-flash.

Might want to hit up the section of the forums for the technical shop manual. Maybe some one in there has the test point procedure to help isolate the hyper-flash. Also visiting a shop and having the BCM scanned. Getting the BCM scanned for any errors, error counts, etc.. may save you a ton of man hours tracking down the issue.

 

[Msfitoy]

I'd go drown myself with a 6 pack and hope it fixes itself...

 

[OFC Ranger]

I just went scorched earth and re-did all my bed grounding points and moved them to beefier connection points. Everything was sized correctly before, now its more overkill than anything.

But whatever, its fixed now. Go figure.

 

[JDowns]

Possible third issue, although unlikely since the lights worked for a long period of time before the fault. Are you sharing the ground? If so you may be adding resistance to the reference ground path. If the design is for low side current sensing you could be adding resistance to a signal ground.

I just went scorched earth and re-did all my bed grounding points and moved them to beefier connection points. Everything was sized correctly before, now its more overkill than anything.

But whatever, its fixed now. Go figure.

I think that answers the question if the BCM design utilizes low side current sensing.

From a spec sheet from TI.

The major disadvantage of low-side current sensing is that the voltage drop across the sense resistor appears as a difference between the supply ground and the load/ system ground. This can be an issue if other circuits are referenced to the supply ground. To minimize this issue, reference all circuits that have interactions to the same ground.

Good lesson in not sharing any grounds, since they are in essence a signal wire., which is a no no.

Great job on getting it fixed, and thank goodness its not a fried BCM, that would be a major PITA. Why this popped up after so much time is a head scratcher though.

Regards,

 

[D Fresh]

Glad to hear you found it!

 

[OFC Ranger]

Well the issue came back sporadically.

I gave up and wired everything into the trailer harness under the truck. I lost my sequential turn signal feature (they blink normal now), but at least now everything is working 100%. No one really knows why the trailer system prevents sequential from working, but whatever.

Added bonus, cause I am using the trailer wiring my turn signals override the brake lights properly and I could reduce the entire system down from 5 wires to 3 because of how trailer wiring works.

 

[awesome1740]

I have the same problem, I’m currently running a putco rear light bar and my left turn signal in the cab is hyper flashing but the turn signals outside are normal speed and my left turn signal on my light bar doesn’t work.

I disconnected the left turn signal and swapped it with the right and the problem moved to the right side. So I believe the problem is in the taillight itself.

 

[OFC Ranger]

Funny this thread got brought back up again, I planned to run a test in the near future and run a wire all the way to a front turn signal to see if the problem persists.

 

[Dirtball]

I have the same problem, I’m currently running a putco rear light bar and my left turn signal in the cab is hyper flashing but the turn signals outside are normal speed and my left turn signal on my light bar doesn’t work.

I disconnected the left turn signal and swapped it with the right and the problem moved to the right side. So I believe the problem is in the taillight itself.

I have the same problem with the Putco tailgate light (LED tail light version) comes with harness that pigtails off both tail lights. I took the truck through a laser wash and immediately turning right out of lot, had a hyper flash inside cab. Pulled over and all passenger side lights are working and flashing normally. The Putco light is not flashing on passenger side. I inspected the Putco harness that that pigtails into tail light. I have continuity through out. I unplug the whole light bar and put everything back to factory and I still have Hyper flash inside, but outside lights are flashing normal. I plug four pin from the light bar into the trailer four pin and the Putco light bar starts working for the turn signal, but still have the same hyper flash. I'm stumped like the OP.

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