Intermittent Wiper and Headlight Issue

[Lezperado]

Good morning,

I'm having some strange issues with my 2015 XL SLT that I'm trying to see if anyone else has experienced. The issue that I'm experiencing is both an intermittent right headlight failure warning and an intermittent windshield wiper failure (inoperable).

 

I would like to start with the headlight issue: when the warning light comes on, the interior signal indicator blinks fast, however, when you go outside both lights in the front and rear are operating as normal. This problem seemingly only occurs below 32 degrees Fahrenheit and when driving in the snow/ice. The warning light will go out and be fine for days and even weeks and then come back. This originally led me to believe that there was an issue in the wiring because when this happened it also affected the mirror turn signal.

 

Secondly, about a week or so after this started, I got into my vehicle and my windshield wipers wouldn't work. I took it to a trusted family mechanic, as I didn't have time to fiddle with it, and he changed the windshield wiper assembly. We came to that conclusion after the mechanic hooked up his computer to override the turn signal and wiper control stalk and he also couldn't operate the wipers. We were both under the impression that this was the issue. I got back into the vehicle following the assembly replacement and the wipers didn't work. We checked the part and the dealership we purchased it from and it was not the assembly. I ended up needed to drive the truck and upon driving it the wipers started working again but went back out again This issue ALSO only happens when the temperatures drop below 25 degrees Fahrenheit it seems.

 

This is where I'm at now and why I'm hoping for some advice/second opinion. The mechanic believes that my fuse box is faulty, however, when we took the fuse box out there is no corrosion. We looked up the wiring schematics and it turns out that GM unfortunately hard wired the wiper relay into the board that's on the fuse box and they are known to go bad but there's no way to really see if it is bad. The only solution is to replace the fuse box itself but the part new is $500 and once the box is opened (if it turns out to not be the fuse box) the parts store/dealership will not let us return it.

 

Has anyone else had this issue before? Are we looking in the right spot? I apologize for the lengthy post but if I don't have to spend $500 on this fuse box I really don't want to. Used was also not an option due to not being able to find a tested unit and additionally when finding a tested unit it was also not able to be returned. Thank you for reading this and for any advice that can be provided.

 

TLDR; intermittent wiper and right turn signal inoperability issue. Mechanic believes issue is $500 fuse box but we can't prove it. Wanting second opinion from masses.

 

 

[TrueBlue]

Anyway you can bypass the hardwired fuse box relay and add another outside of it? 

 

Also, given that you may be parking our rig outside, are your wipers by chance sticking to the windshield?

[Lezperado]

That I’m not sure about. At a fault of my own I’m not great at electronic fixes on vehicles but can do mechanical fixes. I’m sure there’s somewhere I could look that up maybe? Do you have any leads to that? 
 

I initially thought that but they aren’t frozen  because as soon as you drive and hit a bump they will sometimes work. 

[PhilB]

Sounds like it could be a faulty ground wire?  

[TrueBlue]

If you don't do electrical you're kind of at the mercy of someone who does. Wiring relays is not hard, however in today's bus systems in which resistances (impedance), are critical to the system working correctly, it makes it harder to just do things "the old way". If you have a mechanic who's familiar with the bus systems in today's vehicles that would be your safest bet, as they would probably know whether or not you could essentially bypass the relay in the fuse block, and if so what a suitable replacement relay might be.