# Lights Dim, bad ground?



## sdplowing (Oct 7, 2006)

Truck is an 04 2500HD D-Max, plow is a MM2. This is the 5th year I've had this truck and plow and this just started last week. When I run the plow all lights dim; head lights, interior, backup, and the plow slows slightly. I had the batts checked and they're fine. I ran an additional ground from the batt the plow is wired to, no better. Any ideas? Bad alt?


----------



## South Seneca (Oct 22, 2010)

It's gonna snow man! You better get that alternator checked and fixed fast. It sounds like that is the problem.


----------



## sdplowing (Oct 7, 2006)

The alt or the fusible wire that goes from the alt to the batt?


----------



## mwalsh9152 (Dec 30, 2008)

is the plow moving slow? You could be having problems with the motor and thats putting a huge draw on your system


----------



## sdplowing (Oct 7, 2006)

Plow moves slightly slower but not much. When I work the plow it drops the volt gauge way down.


----------



## mwalsh9152 (Dec 30, 2008)

It could be a bad alt, or a bad plow motor. What happens if you put all the accessories in the truck on at once, fan and wipers on high, lights on etc? Does the voltage drop out then?


----------



## sdplowing (Oct 7, 2006)

Voltage only drops when I run the plow. I've turned on everything at once and it didn't affect it.


----------



## no lead (Dec 10, 2008)

you have a bad connection somewhere. i would start at the battery and make sure every connection is excellent. check all at the solenoid and then the motor. run the plow a bunch of times and see if any connections heat up. that is where your problem is.


----------



## forbidden (Dec 22, 2010)

Disconnect the plow + and - from your truck. Connect to a set of jumper cables to a different truck. Run plow. If the second vehicle is dying, chances are it is the plow. If the second vehicle is running fine, chances are that it is the alternator in your truck.

Read these two links on the importance of a proper ground and upgrading wiring. While it is car audio related for high current demands, substitute plow for the car audio device that is the load.

http://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1
http://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1


----------



## mwalsh9152 (Dec 30, 2008)

I doubt its ground related, he stated that he ran an additional ground circuit directly from the battery. 

If youre mechanically inclined and have the time, you could try taking off the plow motor and opening it up and checking for corrosion. If you find any, you can clean it up with a wire brush, or sandpaper, blow it out and reassemble it. Fairly easy way to determine if that is in fact your problem without spending any money. I had never opened an electric motor before, and I had mine back on the truck in less than half an hour.


----------



## s. donato (Dec 9, 2010)

i had the same issue - still do a bit - but my alt was on its way out. 

right now it only dims as i get to the top inch of the lift ram. side to side no issues.


----------



## MrSnow (Oct 31, 2010)

I too had a problem this season with the lights dimming out and the plow running slightly slower. I found my problem to be the truck side power wire, it had a small bad spot in it. I changed the wire and everything is back to normal now. The bad spot in the wire was small and I overlooked it 3 times. Trace down your wires real good, might be as simple as that. If not, keep checking out the other ideas posted on here. 

Good luck and I hope you get it fixed soon. I know I was aggrivated when mine reacted that way.


----------



## jklawn&Plow (Jan 8, 2011)

MrSnow;1223733 said:


> I too had a problem this season with the lights dimming out and the plow running slightly slower. I found my problem to be the truck side power wire, it had a small bad spot in it. I changed the wire and everything is back to normal now. The bad spot in the wire was small and I overlooked it 3 times. Trace down your wires real good, might be as simple as that. If not, keep checking out the other ideas posted on here.
> 
> Good luck and I hope you get it fixed soon. I know I was aggrivated when mine reacted that way.


MrSnow can you describe the bad spot, was it frayed, isulation worn?


----------



## forbidden (Dec 22, 2010)

Read the link I posted on what is a proper ground. If you have a dmm you can check any line, + or - in this fashion to ensure that your connections are as solid as possible. CCA wire is a culprit in many occasions. Improperly guaged wire is another. Just because a wire says it is such and such a guage does not mean that it is. The more connections in the wire, the more the resistance there will be through it. If you have a crimped on terminal for example and the crimp is corroded or loose yet, it would also be a prime culprit.


----------



## MrSnow (Oct 31, 2010)

*The bad spot description*

The bad spot was on the truck side of the wiring. The wire had discoloring and showed sign of corrosion. When I took a knife and peeled the coating away, I found the wire to be full of corrosion. I couldn't find a butt connector that large, so I had to improvise until I bought a new power line for $35. I wish I took a picture of it so I could show you. I hope this helps you. Sorry it took so long for me to answer, but with the past and current weather conditions, I was unable to turn on the computer.


----------



## Plow man Foster (Dec 10, 2010)

Hey my buddy has a GMC 4500 with a boss plow he doesnt use the plow lights only the truck lights....and his head lights dim too.....
We think its just because hes running the truck with one battery instead of 2....


----------



## forbidden (Dec 22, 2010)

The alternator in any given vehicle was designed to run the vehicle and it's standard or optional factory installed accessories. It was not designed to operate the vehicle and a high current draw from say a snowplow or car audio system as well. The culprit is the availability of power. No number of extra batteries in the world is any good if they can not be recharged. Look to a larger alternator and not a rewind that is "higher output" in the same small case. That equals more heat which equals a failure of the alternator right when you need power the most.

We notice things the most in lighting circuits as it is something we can see. I have a 25 year background in 12volt audio, for me, I can hear it in the performance of an audio system before I even see it in the lighting circuits. Excessive draw affects everything in the vehicle that is drawing current, heaters run slower, lights dim, an audio system won't go as loud or fuses start to pop......


----------

