So first off - I am not looking for someone to say "hey I know exactly what that is", although that would be neat. This is more of a very odd experience I just had and I want to document it and see if anyone is interested in talking through it or bouncing ideas out there. I guess that's how most of these threads on here are though!

2017 F350 XLT Premium 6.2L Snow Plow Prep XXHD Alternators.

So as many might know I have a rather elaborate lighting set up in my truck. I used a Feniex 4200DL controller to run everything. This controller gets it's main power via an 8AWG fused wire (60A Fuse) that runs directly to the battery. Then there is a ~1A 12VDC "Ignition" wire that would tell the controller that the vehicle is on, so that it isn't running 24/7 . When the "ignition" wire sees power, the controller starts up, when there is not 12VDC coming from that wire, the controller is in Standby mode. Instead of wiring that 12VDC "Ignition" wire directly TO an ignition switched wire, I ran it to Upfitter 1. I did this because I could leave the switch in the on position and the controller would function as if it were wired to an Ignition-On source. However it also gave me the option to turn the entire system OFF, which I figured would be great in case of malfunction. It's been installed 2.5 years now, with only one issue early on, which was actually an internal defect in the controller (Feniex OVERNIGHTED me a new one, talk about C/S). Today, I was running through the various light configurations while recording it, for an information video on the installation/controls that I am making. Things started getting weird a few minutes in. Here's the sequence of events:

1. 2/6 lights on the front end of my truck stopped working, which is odd because there is a single wiring bundle feeding power to all 6 of them. So for 2 to cease working while 4 others continued to work was essentially impossible.

2. When I went into the truck to check the controller, nothing appeared wrong. It was displaying activations and functioning as usual.

3. I turned the truck off, and instead of simply turning off, the controller power cycled 3 times, and stayed on for about 10 seconds.

4. Turning the truck back on, the controller functioned normally. I activated ALL lights, and went for a walk around.

5. The 2/6 front mounted lights were still inop.

6. Dash lights worked fine.

7. ALL other lights on the truck that are controlled by the controller were inop.

8. Checked my ground point first with a test light, all good.

9. Checked outputs on the controller with test light, all good.

10. Checked for power at all accessible lights with test light, all good.

11. Got out a volt meter (should have started with one) and checked voltage across the Positive bus and Negative bus at the controller - barely registered voltage (3-4VDC). These busses are both PRE-controller. That would certainly cause lights to be inop, as they mostly require 12-24VDC.

12. Checked all fuses in entire installed system, all good.

13. Made sure my meter was set right, went back to the controller, began checking each terminal on the Positive bus with the meter and now all showing a strong 12VDC.

14. Everything now functions normally and shows proper voltage.


So to recap, everything went from being fine and functional, to haywire in seconds. Issue appeared to be low voltage coming into the controller setup - with that voltage being supplied by Upfitter 1. As I began checking connections with Multimeter, system recovered and voltage bumped back up. Truck was running the entire time, no other odd symptoms in truck systems were noticed. It is also currently 12 degrees outside.

I can't really think of any reason off the top of my head for there to be a dip in voltage here, which is why I'm writing it all down. Thoughts? Or just chalk it up to a WTF situation and move on? I personally just hate when things go wrong and I have this NEED to figure it out!! So let's talk it out!! Thanks y'all!

 

Follow-Up question - Do these trucks have a system that would prevent excessive draw on the electrical system with the key only in the ACC position and the truck off when temps are extremely low? Scenario is I just put the truck into ACC position and was experiencing the same low voltage issue with the lights as before, except as soon as I turned the truck on, everything was totally normal. Currently 11 degrees F. Just adding all info here...

 

How’s it grounded?

 

Grounded via a 12 or 14 AWG wire running up to the front driver side of the engine compartment, it is grounded to the Stud next to the upfitter switch wires. It is not grounded directly to the battery (like it probably should be). However it's been years with no issues and my other driving lights that are upfitter controlled are grounded there too. Think that could be a contributing factor?

 

I’m reacting to the 3-4v measured at the controller. In my experience people rarely get positive wiring bad, but often junk for ground.

I’d measure voltage controller positive to body and see how it differs.

if you’re 13v at the battery... and 4v and the controller, the possibilities are:
bad ground connection
bad positive connection
faulty wire
grounding out
high current draw relative to wire gauge/length (voltage drop occurring in length of wire)

 

Grab a length of wire attach it to the meter negative probe and measure the voltage for the + of the controller to the negative of the battery. That will tell you if you ground or ground wire is bad. You can also do the test negative from the controller to positive on the battery to test the plus side

 

My plan is just as you said Wildcard - grab my jumpers and run a test ground right to the battery to measure voltage. I've been out and about several times since the post this afternoon with no issues...but that doesn't make me want to know any less. Today is too damn cold to spend more time outside than I have to, so I'll wait until the temp goes back above freezing. I've spent too many hours freezing my a$$ off in the driveway to count...but well be back to mid 40's this week so I'll get that test done and then likely run a fresh ground wire straight from the battery, just for kicks.


Thank you to Section and Wildcard for getting in on the conversation. I'm very meticulous with my wiring and installs and plan everything out carefully but sometimes need a good conversation on the theory of troubleshooting!

 

It’s highly unlikely your factory chassis ground is gorked, so you should be able to test to any exposed metal as ground or, the metal part of your cig lighter in the cab.

But if you get weird results that way... yes, going to the source is wise.

 

Did you find a solution? I'm having a similar issue. I'm running two smaller lights on the front of the truck using the upfitters. Worked great for over a year and now it outputs low voltage and the lights wont come one. the second a load is applied the voltage drops to 2-4V. truck off with no load it was 13+ even when the battery was only 12.7. Driving me nuts!