Anyone put a plow on '14 gmc need light help

pancepance · October 30, 2014

Posting here instead of the plow forum because I feel its specific to this model truck.

Truck is a '14 sierra 1500 denali.
The truck is real nice but the stock headlights were horrific. I replaced them with HID kits using relay harnesses and capacitor to get it working right. Once installed have worked flawlessly since May.
Had a new plow installed last week and For some reason now the Hid's do not work. Well they sort of work but only for a couple of minutes. Now when headlights are on the hid relays to consistently buzz which I know is trying to turn itself off/on/off/on. The lights will stay on for a while but then crap out completely. The installer is blaming the Hid's but I had the exact same kit in a tundra with a plow and they worked fine. I'm at a loss what to look for. Was thinking maybe I could just have the plow without the switch for "plow/truck" lights. Would that work? I don't mind having to turn off my headlights when the plow is on and visa versa. I am not sure that will work because I'm not sure how the plow gets the signal for the lights. I know the newer trucks are very sensitive to anything electrical. Was hoping someone may have a similar issue with one of these or the Chevy counterpart. I just cant figure out what changed between having no plow and now a plow. From what I understand the plow harness should just go in line before where the factory bulb would be. If that is the case why would it interfere with the hid's? Is there something I am missing? I admittedly am no expert in plow wire harness set up. Its just frustrating because nobody wants to help. Plow installer blames hid's, Hid's blame the plow installer. I know these trucks are finicky. I can tell that when the hid's do shut off its being done so by the truck. I can hear a distinct "click" from somewhere other than the hid set up. Almost on opposite side of engine compartment. Seems that a computer or another relay is turning the fee off.
The only suggestion I've been given is to run the hid's from one side and only hook the plow up to the other. I only need one factory connection for the hid's as they both work off one side. I am not sure the plow can work off one side only though. The suggestion was feed hid's from pass. side and feed plow from driver side.
Just figured I'd inquire.
If nothing comes up I'll be sure to post what winds up happening as I know as time goes on I will not be the only one with this type of issue.
And yes, I know, I shouldn't have put a plow on this truck in the first place. Now I just need to fix the issue cause its dark early and I am running into issues getting home from work cause the lights don't work. Any thoughts are appreciated.

No ConeSS · October 31, 2014

What about taking the HIDs out *temporarily* and putting the original bulbs back in and seeing if there is still an issue? If so, not HID related and it's something with plow (or inadvertanly done during) install. If problem goes away, then there is an issue where the HIDs and plow do not get along.

Just thinking of an easy troubleshooting method to eliminate or narrow down where the issue is...

pancepance · November 1, 2014

I was out of town when I made that post. I was hoping to have some direction when I get home Saturday cause both the plow installer and the hid company are closed on weekends.
I spoke with both in last few days. Still getting the "must be the other ones fault" But I did get a wiring diagram from the plow manufacturer which I will use to make sure all is done to their spec. Then I'll try process of elimination. The hid comp. told me how I can disconnect them and run a 12v feed direct from the batter to make sure they are still working properly. I also figure with the plow wiring schematics I should be able to get that part isolated and out of the situation as well.
The plow wiring does seem to be very intricate. It has relays and power sources and separate switches. I assume one or many of those could be causing issue by themselves.
I figure once I isolate both systems I can at least figure out what combo creates the issue. Not sure if that will actually get me any results but its a start. Being away all week on work and could think of nothing other than my light fiasco was fairly unproductive with regards to my job but in a few hours I'll be home and start removing stuff and see what happens. From what both places said just getting to the headlight housings is a major undertaking by itself. I'll search here on the flight and hopefully find a step by step to getting access to the lights. It seems fairly simply from what I remember but the installer said there are 2 bolts on top and 2 on bottom. He claims I have to remove the top half of the bumper just to get to the other bolts. That seems wrong to me but I'll find out tomorrow.

If anyone knows a post on removal of the gmc front bumper I'd appreciate it. Otherwise I'll search here till I find something. Of if he is wrong and I don't need to remove it to get to lights please let me know.

Imcrazy · November 1, 2014

I didn't think you could get a plow prep package on a 1500 in anything but a regular cab.

GMMediumDutyMQ · November 1, 2014

I didn't think you could get a plow prep package on a 1500 in anything but a regular cab.

You can't...

pancepance · November 1, 2014

Absolutely True,

No plow prep package for these trucks.

redwngr · November 2, 2014

Imcrazy is correct, on a 1500 snowplow is only available with reg cab.

VYU Snow Plow Prep Package includes power feed for backup and roof emergency light, (KW7) 170-amp alternator, forward lamp wiring harness, (TRW) Provision for cab roof mounted lamp/beacon, (K47) high-capacity air cleaner, (NZZ) underbody shield and Heavy Duty Front Springs. VYU not available with 20" wheels without Z71 suspension.

1 - Only available on 4WD models.

Spurshot · November 2, 2014

Wow. Plowing in style.

Anyway...sounds like the expensive truck has a cheap light kit on it. Do you have a relay circuit to power the HID lights?. If so, only one side of the factory harness should be powering the HID relay. If you don't have a relay harness for the HID lights, get one.

seansharley · November 2, 2014

Sounds to me like the additional lights/wiring is overloading the circuit breaker, unfortunately the easy fix would be run factory lights in winter, hid's in summer. Might work, but kind of scary putting a heavier breaker in. I bet a good GM tech would have the answer