# Truck and plow lights flashing



## DeltaT (Dec 12, 2015)

I am having an issue with the lights on my Ultramount. I did quite a bit of searching, but didn't really see anyone with the same problem. I have a 2002 2500HD. I traded some HVAC work for the ultramount, but had to put all the truck side stuff onto my truck. After I installed a 3 port 3 plug isolation module onto my truck, I realized the plow was only 2 plug. So I bought the conversion harness to adapt it. Today I finally got everything installed and hooked the plow up. The plow control works fine, but when I turn the lights on, the plow lights and truck lights just flash back and fourth. I will also add that the isolation module I bought was a used unit 

This is my first plow, so I am new to all of this. I have good electrical knowledge. Is there something stupid I may have done or overlooked. I appreciate any and all help I can get from here.


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## dieselss (Jan 3, 2008)

sounds like a ground issue.
where did you hook the ground for the lights? have the wiring diagrams?


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## DeltaT (Dec 12, 2015)

I have the main ground bolted to the grounding bracket that the Chevy's have. Everything is grounded back to that location right? 

I will say that I can hear a clicking noise coming from the module when the lights are flashing back and fourth. It's not a sporadic flashing, but a constant flashing almost like a blinker.


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## dieselss (Jan 3, 2008)

the plow light grounds. 
the ultras have differnt lights then your older ultra.

what grounding bracket?


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## Randall Ave (Oct 29, 2014)

I assume its a gasser, driver's side left front corner of engine there is a bracket that says ground on it. Just did an install on a chevy. I ran the grounds directly to the battery.


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## dieselss (Jan 3, 2008)

Ok I know which one your talking about. Alt bracket, aluminum.


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## DeltaT (Dec 12, 2015)

To the right of the motor there is a junction box that houses the positive connections for the alternator and right above that is a metal bracket labeled GND. Seemed pretty convienent since the side terminal batteries are a pain. 

I did a little more research and saw something about the 2002 Chevy having a switched grounding system? Could this be an issue?


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## DeltaT (Dec 12, 2015)

Randall Ave;2073062 said:


> I assume its a gasser, driver's side left front corner of engine there is a bracket that says ground on it. Just did an install on a chevy. I ran the grounds directly to the battery.


It's on my Duramax


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## Randall Ave (Oct 29, 2014)

dieselss;2073066 said:


> Ok I know which one your talking about. Alt bracket, aluminum.


Yup, even if this isn't his problem he should run a ground strap from the battery to that bracket. 
Don't no if my install works, customer never brought me the used plow he bought, and he ain't answering his phone. Probably a money thing.


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## dieselss (Jan 3, 2008)

I did a little more research and saw something about the 2002 Chevy having a switched grounding system? Could this be an issue?

The easiest way would be to test light the headlights and verify.


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## DeltaT (Dec 12, 2015)

Sorry I worded my question badly. If my truck has a switched ground system, is there something I have to do in the wiring to adjust for it?


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## Randall Ave (Oct 29, 2014)

In your directions for the headlamp connections, it said to check for where your grounds were, and to connect per there instructions, on the plow side headlamp adapters, the ground, or common wire jumped from one plug to the other. You should have connected to the corresponding headlamp plugs with the grounds to the grounds on the plow harness plugs.


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## RamdyB (Sep 22, 2021)

Sorry to awake the old thread. Did you ever figure out the problem? My 07 just started doing this after I pulled it out of storage


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## Mike_PS (Feb 28, 2005)

RamdyB said:


> Sorry to awake the old thread. Did you ever figure out the problem? My 07 just started doing this after I pulled it out of storage


maybe someone can/will assist you but you may be better suited to start your own thread as the thread starter hasn't been back since starting this thread


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## RamdyB (Sep 22, 2021)

come to find out. My running lights weren't working. Turned out to be my parking light relay.


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