# Truck and plow lights on at same time



## mattpiotrowski (Jan 7, 2010)

Hello All, Hopefully somebody can help me here. I have a newer Western Uni mount on my 86 GMC 2500. it has the 9 pin, 2 relay wiring harness. when i plug my plow in both my truck lights and plow lights are on. I know on westerns when you plug in the lights it switches one to the other. I replaced both relays with napa(192d) 87a relays and that still did not solve the problem. should the wiring harness be grounded anywhere? Any information is appreciated Thanks

i forgot to mentioned that it seems like after the truck gets warmed up with the plow on the lights start to flash like they are trying to switch over. if i unplug the head light harness to the truck light harness under the hood it acts fine for a while and does it again and sometimes it will be fine all night


----------



## 2006Sierra1500 (Dec 28, 2011)

Is the extra light really a bad thing?


----------



## mattpiotrowski (Jan 7, 2010)

2006Sierra1500;1690506 said:


> Is the extra light really a bad thing?


No its not. Im sorry i forgot to mentioned that it seems like after the truck gets warmed up with the plow on the lights start to flash like they are trying to switch over. if i unplug the head light harness to the truck light harness under the hood it acts fine for a while and does it again and sometimes it will be fine all night


----------



## dieselss (Jan 3, 2008)

Well you said you got the 87a relays. Did you put the pins back in the same way and on the same relay number as per westerns wiring diag?


----------



## mattpiotrowski (Jan 7, 2010)

dieselss;1690522 said:


> Well you said you got the 87a relays. Did you put the pins back in the same way and on the same relay number as per westerns wiring diag?


Yessir, I went to Westerns website and got a diagram what wire goes to what prong on the relay prior to disconnecting


----------



## dieselss (Jan 3, 2008)

Well test light time. Start cking the wires to see what you have and don't have. Start with the gnd wire first. The blk/og one. With plow hooked up it sends gnd signal to the relays and the contacts close sending pwr to pin 87 out to the plow lights


----------



## mattpiotrowski (Jan 7, 2010)

dieselss;1690530 said:


> Well test light time. Start cking the wires to see what you have and don't have. Start with the gnd wire first. The blk/og one. With plow hooked up it sends gnd signal to the relays and the contacts close sending pwr to pin 87 out to the plow lights


ok. does that ground tie into the same black-orange wire that goes to the selonid? i have the tower style one and the 2 small prongs one wire is black/red(i belive) and the other is black/og. should there be a jumper wire type that goes from any of those wires to the ground on the battery?


----------



## dieselss (Jan 3, 2008)

No its ground comes from the blk/og on the plow motor the relays that is


----------



## mattpiotrowski (Jan 7, 2010)

Ok. i get what your saying so the ground goes to the motor on the plow side (pump motor). But just out of curiosity, what would ground the harness for the lights when the plow is not on the truck?


----------



## dieselss (Jan 3, 2008)

Nothing. That's what the pin 87a is for. It goes pin 86 to 87a. When you gnd out the relst it goes pun 86 to pin 86 and plow lights ate lit


----------



## mattpiotrowski (Jan 7, 2010)

dieselss;1690577 said:


> Nothing. That's what the pin 87a is for. It goes pin 86 to 87a. When you gnd out the relst it goes pun 86 to pin 86 and plow lights ate lit


ok. so what pins should have power when i hook the plow lights up


----------



## dieselss (Jan 3, 2008)

Ok. Gimmie a min and ill look it up


----------



## mattpiotrowski (Jan 7, 2010)

dieselss;1690666 said:


> Ok. Gimmie a min and ill look it up


ok. can you send the link also? thanks


----------



## dieselss (Jan 3, 2008)

Western plows .com. libary. And 3 and 4 port and relay wiring. 
Without plow
Pin 30 yel to pin 87a org 
Pin 86 brn is parking 

Plow hooked up.
Pin 85 blk/og gets gnded 
Pin 30 yel sends pwr to pin 87 blk out to plow


----------



## Fixx (Dec 20, 2013)

check the brown wire feeding all the releys,,it they dont have power from the parking lights all the lights will come on...or the plow plug is not completeing a ground to turn off the truck lightd..


----------



## mattpiotrowski (Jan 7, 2010)

Fixx;1691045 said:


> check the brown wire feeding all the releys,,it they dont have power from the parking lights all the lights will come on...or the plow plug is not completeing a ground to turn off the truck lightd..


I Checked all the wires and have power going to the ones that should have power to them when lights are activated. I put a jumper wire from the ground straight to the negative to the battery and still have nothing.


----------



## Fixx (Dec 20, 2013)

mattpiotrowski;1691195 said:


> I Checked all the wires and have power going to the ones that should have power to them when lights are activated. I put a jumper wire from the ground straight to the negative to the battery and still have nothing.


that is the most commn problems i see,,if the parking lights are not worklng on yhe plow then iys the brown wire that goes ti fire all releys.


----------



## dieselss (Jan 3, 2008)

What gnd wire? The blk/og at the relay?


----------



## dieselss (Jan 3, 2008)

Are you 100% sure you got the right relays. Sometimes the 87a (5pin relays ) have a jumper for 87 and 87a to be active at the same time. 
With plow hooked up. Test light both 87 and 87a pins to see if you have pwr at both


----------

