# Exterior lighting problems caused by plow circuits (03 Chevy w/ Western plow)



## BigRedBarn (Jan 4, 2003)

I've had some weird things go on with my truck. It's a 2003 Chevy Silverado LS 2500HD regular-cab long-bed with 8100, Allison, snowplow-prep, trailering package, and 7½ foot Western Ultra-Mount plow (installed by an outfitter but coordinated & paid for through the car dealer).

I've been having trouble with the exterior lights. Sometimes a rear taillight won't work, then it'll start working again, then stop working. More often that not it's OK. 

More frequently is that the left headlight lights up when it's daylight and the daytime running lights are on. If I go into a dark garage or turn on the headlight switch, both headlights come on and the daytime running lights go out; so there's no problem there. The right headlight works fine when it should.

I've had trouble with the radio at times, too. The display will work fine. It will look like everything it working (it'll accept a CD and eject it, the display works OK, etc.). But, no sound comes out. Not on CD, or on any radio station. If I turn the truck on and restart it, the radio will be fine.

So, obviously, none of these problems happen when I take it to the dealer. Even before he tries to fix it he claimed he sees this sort of thing all the time. He claims it's either a snowplow or a remote starter causing problems like this (there's no remote starter on this truck, just the plow).

Is this dealer making any sense? Has anyone else seen these sorts of electrical gremlins?

My main worry is that my taillight won't work properly when I need it the most (like when I'm followed by a police or sheriff's car). The bulbs are all fine, but certain lights come on when they shouldn't and others don't when they should. I haven't been able to tell everything that going on, because it's a bit difficult to do so when driving. But, I notice the left headlight a lot in daylight when I pull into the local convenience store or drug store and see the reflection in the store window. The daytime running lights seem to work OK.

I appreciate any assistance I can get. I tried to search this topic a bit, but got too many hits that weren't of value. Thanks in advance for any help you can offer.


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## Earthscapes (Feb 2, 2001)

It sounds like you may have a bad relay in your plow light harness. I believe the westerns use 2 or 3 relays like my snoway does. I had one go bad last year and my lights would flash (for no reason during the day) if i was on a bumpy road...kinda cool cause the people would get out of the way. 

But it sort of does not make sence because your also saying you are having problems with the radio. I would call the western dealer that installed the plow.


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## wyldman (Jan 18, 2001)

The left headlamp problem is most likely a relay,or wiring problem related to the plow.

The tailights aren't really wired to the plow harness feeds at all,except you usually have to tap into the marker lamp circuit somewhere up front.If you had a problem there,it would most likely be one front marker not working,or all the marker\tails lamps would be on when they aren't supposed to be.


The radio problem sounds like just a bad radio.It's a fairly common problem on some GM radio's.Dealer should warranty it.

If the dealer contracted the plow install,then they should be responsible for any problems with the plow wiring,or at least subbing it back to the installing plow dealer.


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## wxmn6 (May 23, 2001)

It does sound like a bad relay in your plow light harness. I would take the truck back to whomever did the install for you. But if you don't want or feel like taking it back to the outfitter, then you could try and trace the problem yourself. Pop up the hood and find the relays for the plow lights. Try changing one with a new relay, one at a time. If you tried changing all relays with the new relay and it still don't solve the problem, then it could be a bad ground or loose wiring connection or a nick in wiring causing it to short out. You could try to trace all the wires, but it would not hurt to take it back to the outfitter, let them take the headache, not you.


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## BigRedBarn (Jan 4, 2003)

Thank you for the quick replies. 

I don't even want to get close to jeopardizing either my vehicle or plow warranty. 

I'll ask the dealer to have the truck serviced by the plow installer. The reason I had the dealer handle (coordinate) the plow installation is so there'd be no finger pointing. 

The dealer stated when I bought the truck they'd work with the plow installer for any warranty work or problems (I hope those aren't famous last words).


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## Crash935 (Sep 3, 2003)

Hey bigred, the problem with the headlights is that you have an early edition of the harness, western didnt catch the problem in time and has sent out service bulletins to all the dealers . What is happening is that the relays are back feeding on the ground side of the relays, Your western dealer just needs to install a jumper wire with a diode in line in the proper place on the ground leg of the relays. Oh yeah, this will be covered under warranty by western.


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## Little Jay (Dec 12, 2001)

To expand on Crash's comment a bit...
I had similar problem without the radio issue...
The outfitter used an older version of the wiring harness, and used an additional factory given harnesses to make the old one work. (does that make sense?) Instead of having one new complete harness, they have older versions and add sections to make it all work on newer trucks. 
These combinations often have problems and are worked out slowly since production moves forward and fixes to older stuff does bring in as much $...
My problem was finally fixed by finding that the added section had an extra ground and bla bla bla.- it was fixed.
I would offer the advice of standing in the shop as the outfitter trys his hardest to track down the problem-he wont unless he's a very informed about the electrical skematic of all of the versions, and additions to Western's components. After he fails to find the problem, have him order a new complete wiring harness and throw it on.


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## easthavenplower (Aug 21, 2003)

it almost sounds like a bad ground to me weather its the plow or not thats the question


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## BigRedBarn (Jan 4, 2003)

Again, thanks for all the suggestions and information.

I don't know where else I'd go to get info on truck problems caused, possibly, by a plow installation.

Now, if I can just motivate myself to get that nice new urethane blade installed before it snows. Anyone got any recommendations as a result of their installation experience? Should I leave the extra 3 inches at each edge? I only do rural driveways, so I don't need to snug up against curbs.


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