anotherfordguy

Hey guys, I'm pretty stumped here so I figured I'd get some opinions from you.
I am currently trying to wire up my Diode Dynamics C-Clamp LED lights as part of my retrofit and I've hit a small hurdle. To pretty much sum up how these LED's work:
They have 4 leads coming off: black, yellow, red, white.
Black is for ground.
Yellow ties into turn signal (these are switchback).
White turns into low power (these illuminate white whenever headlights are on as additional brightness is no longer necessary).
Red is high power (this signal acts as DRL and the LED's are powered on brightest until low power signal is detected).

So I have all of these functions working correctly except switchback. My truck didn't have DRL's but my OBDLink MX came in today so I enabled my fogs as DRL's and tapped into them for these LED's to work as DRL's. Low power is tapped into regular headlight, lowbeam circuit (so led's cut power whenever high beams are on).

So here's the kicker. Switchback function works perfectly fine whenever engine isn't running. The moment I power on the engine and put a turn signal on, regardless of whether or not its the hazards, the power is cut to the entire circuit and both the LED and turn signal lose power. I did have load resistors wired up as I've replaced my front turn signals with LED's as well. Thinking this may be the issue (2 taps on each wire) I turned turn signal lamp outage warning off in Forscan and removed the load resistors from the circuit.

So as of now there are only 2 taps on that circuit, ground and turn signal. Looking in Forscan, I get these 2 error messages:


BCM indicated a short to ground but I have no idea where this could be occurring. The circuit runs fine until I add in the C-Clamp LED.
Weird since they run fine when engine is off and testing them with a 9v battery they ran fine.

Here is what I'm tapping into if that helps.


Moving ground doesn't solve issue either.
Insulation is a little chewed up from the vampire connectors I used with the load resistors but the wires appear to be in good shape still.
Any help would be sincerely appreciated!

Additionally I have tested these wires with a multimeter so I know they are the correct ones. However I did noticed I'm reading about .1 VDC when engine is running off the ground.

anotherfordguy

bump

Chad Walker

Don't ground to the plug if that is what the picture is showing. Use a bolt or some other chassis ground and see if that does anything.

santa06

Just a shot in the dark, but bcm have to be matched exactly to truck options.

You pretty much order it with your vin.
Just changing ECM program for Dtrl lights might not be enough , could bcm also need program change.

Cut and paste from Rnlcomp posting on Forscan.

I started by not only activating my DTRL but I also programmed the BCM (body control module) to make my fog lights dtrl, Ford's IDS does not give that option, IDS is limited to either headlights or front turn lights (2013-14).

Now when ever I shift out of park, they come on. With Ford IDS activated DTRL, using headlights or turn lamps come on only when in drive. Using forscan they are on in any gear position other than park.

anotherfordguy

Thanks for the suggestions guys. I've tried chassis grounds, grounding in other circuits, etc, and nothing works. I'll just have to live with the switchback function not working properly. Contacting Diode Dynamics was kind of a waste of time, all I can get is generic instructions, not vehicle specific instructions which is odd considering this is a vehicle specific product. When I get some more free time I might try using a relay to power the switchback function, although I'm not confident it'll work.

Other functions work fine though, and these lights are sharp!

Eco-BEAST 28

I have the exact same problem with the exact same lights and almost identical situations. Heres what you can do to fix it. Short term, reset it every time it happens via a for scan app for your phone. Some trucks are touchier than others but mine does not like these new lights and I've had to do this several times. Now it wont even let me clear it so i can't use my switchbacks the way they were designed. Long term fix.... your truck thinks something is wrong because of the draw from the new lights and fancy features. What i did was take a wiring harness and run power and ground to only the switchbacks and power them to a fuse that was empty in the engine fuse box. Im literally in the middle of doing it right now so i will let you know if it works and i can also grab pics and schematics for you if you are interested.

Eco-BEAST 28

Got the harness installed to help take the load off the BCM and give the switchbacks their own power from the battery and relays. However, it is now obvious that my problem is much later then I though. Coupled with the DTC's that I have and the fact that I can't clear them, I believe my BCM is done I've ordered a replacement and it's on its way but I will now have to swap it and take it to Ford to have it programmed not the result I was hoping for, hopefully you have better luck

anotherfordguy

Shoot yeah I wish I had checked this earlier. I did some digging and bought 3 days worth of the Workshop Manual in order to pour over the Wiring Schematics to see where I was going wrong. Come to find out that the BCM is protected by a MOSFET that will cut power to the BCM when a short to ground condition is detected in either turn signal circuit (drivers or passenger side, considered 2 separate circuits).

According to the manual the system has levels of fault tolerance built in, roughly in intervals of 200. At 200 shorts, the DTC won't clear until the issue is resolved and I believe it will clear IIRC after a certain length of time w/o being tripped again. This will keep on until the codes cannot be cleared and so on and so forth until the BCM is damaged and needs to be replaced. I will try to use a relay for signal and draw the power elsewhere as you suggested but if that causes the condition again (which I don't see why it would/should to begin with) then I'll likely leave it alone as I don't want to damage my BCM.

Hate to hear it man, I know that won't be cheap.

Eco-BEAST 28

Thanks for the info, that makes sense about a certain amount of faults before it throws the DTC because it would work fine for a week or so and then all of a sudden it would throw the code which must of been me hitting the tolerance. I was able to reset it 4-5 times before the final code. From what you said it sounds like I allowed it to happen so many times I damaged the BCM for good. I got one off another truck for $138 and I'm going to have to pay Ford prob $200 in labor for them to install it and program it but the only upside I can see is I may have resolved this issue for good and I will finally be able to enjoy my lights without worry. This has been about a 4 month process of trial and error

Eco-BEAST 28

Here is how I ran my tap