Tail light mod (both lights used as brake and signals)?

That is about the greatest tidbit I’ve seen on tw! Thanks for opening the door

Forums like these are first and foremost peer to peer IMO.

edit: the good posts unfortunately get lost in all the bullshit… so I screenshot your post

 

No problem. I spent hours researching anything and everything I could and funny enough I found most of the info I needed here on TW. Once I figured out that little tid bit, everything I have done electrical related I always look to see if I could build a harness for it so I wouldn't have to cut/tap/splice into the OEM harness.

Right now, I am trying to find the male side of connectors for the switches so I can relocate them into areas that work better for me.

 

Yesterday I installed Diode dynamics “turn as tail” module along with 6 ohm 50 watt resistors...I also installed Led bulbs. Install went quite well, soldered all connections, mounted resister up high, verified DD module had no broken wires and clear silicone sealed them. Before buttoning up tails, I verified everything worked. 4 ways, brakes, turn signals etc. good ? Nope. Headed down road and I notice my left, only left signal not working. 4 ways will engage but left side won’t flash. Stop, restart, they work. If I have brake pedal pressed, they strangely re activate.
I pull both tails and verify all wiring. It is correct.
I see a post on here about “extra in series resistor. Is that what I need? I guess I should have “ohm” checked my 6 ohm resistor. I guess it’s possible it failed spec range when built. I’ve installed resistors in front on my 78 TA ( LED switch backs for DRL) with no issues.

any thoughts?
Thanks

 

Did you follow the diagram that is floating around on this thread? Any chance you can post up pictures of your install?

 

No pics tonight, truck is outside and I’m done for the day. I’m 110% positive it is correct. I did passenger side first (no issues). I followed print out posted here.
I’m curious if I possibly have a bad DD unit or funny quirk I need more than 6 ohms. I did go out earlier and DVM’d resister and it is 6 ohms.

 

All trucks are different. 1 resistance may work on 1 truck, but not the next. When the turn signal is totally “out” it means too much resistance on that circuit. You need LESS than 6 ohm. Try a 10 or 20.

 

ok, I think I understand that. If I have 6, why try 10? Isn’t 10 more than 6? I actually thought about inserting old bulbs (non led) to see if they worked.

 

Yes it’s a higher number but higher resistance.
Edited

 

I'm gonna argue that.

10ohm is higher resistance than 6 ohms.

 

Doh. Brain fart. This is correct. Higher number= higher resistance. the truck is seeing too Much, so dropping the resistance (or raising it however you wanna think of it) will eliminate the dead flash.
If you don’t have enough load the truck will hyperflash. Too much and it will flash Once and go dead. You need to find the happy medium of resistance the truck likes.

 

You wanted to say he needs more current. More current will require less resistance

 

Makes sense...but is it possible one side is ok with 6 ohm and the other needs 4 ohms? It does make sense that with no flash there is too much resistance.

 

Yes you can mix resistances. As long as the end result is correct functionality.

precisely

 

I'm not sure how the unit works, but basically it would be monitoring either the total circuit resistance or total circuit current (they go together basically)

With all the filament bulbs in place they pull a certain current. If their resistance increased (bulb burnt out) then the unit would be able to detect that.

On the flip side if a short circuit were to happen (resistance too low) then it would possibly detect that and not allow the system to operate.

All you need is to find the load of the stock system and add a resistor sized to bring it back into spec.

With all that said, most of these items are labeled in watts. I think even leds are in watts. In the end it's just algebra

 

Yup. Unfortunately, I fell asleep in math class.
Fortunately, I excelled in auto shop.

 

I think the hardest part is determining the resistance of the led that is replacing the bulb. Bulbs can be checked with a meter on ohms.

The led kinda can but you have to have polarity correct and I'm not so sure they are as "simple" to figure as standard filament bulbs.

We've exhausted my current electrical knowledge

 

Update: issue seems to be corrected.

8/29/20

Saturday evening, prior to my post...I double checked all my connections. I did come across one solder connection I just didn’t like the looks. I re did this connection, buttoned lites up and called it a day. I started my truck Sunday only to move it so I could get my Trans Am out. While it was running, I noticed the left blinker was working and did not stop like it did before I re soldered that one connection. This morning I drive truck to my morning run location....no issues. I’m almost certain I had one poor solder connection that caused my issue. The 50W 6ohm resister seems to be sufficient. I am putting in heat shrink spade connectors...so if and when DD is acting up, I can unhook and return to factory settings. I’ll also keep old bulbs in glove box.
Thanks guys for chiming in...this is a nice mod in my opinion.
Cheers!

9/2/20
issue came back tonight. I will need to address resistance issue or return to factory settings. I thought maybe it’s the LED bulbs...I switched drivers and pass side and still had error. I doubted it was bulbs but thought I should try.

diode Dynamics believes I have a bad module- sending one out to me today. Good company.

9/6/20
received new DD parts (very fast shipping). Wired up new unit, works as advertised...until driven ugh. Tried replacing 6ohm with 4 ohm resistor and signal doesn’t even come on at all.
9/7/20
DD Doesn’t have any suggestions to fix it. One thing suggested to try is use module with out resistor (which works until headlights are on, and then hyper flashing starts).
I decided to try 2 4 ohm resistors in series (8 ohms total). So far, 10 miles of driving and 3-5 minutes of idling with left blinker on...has proven to be the fix.
If this doesn’t fix it, I am done and going back to OEM. Lesson learned, use spade connectors so returning to factory settings is quick and easy. Also, have a selection of resistors on hand just in case. 6 and 4 ohm were good choices for me.