Suggestions take truck for hook up repair battery connection

I had the same problem. Plugged in to shore power, the trailer battery charged and all was fine. Trailer lights and brakes worked fine when plugged in to the truck. Traveling for several hours with the fridge on produced arrival with a dead battery. Granted, the single camper battery was 5 years old. The RV tech checked the truck output with this:


The truck was producing the 12V on the charging line, but the camper battery was not taking it. Then he found a bad ground in the camper. Problem solved. Now with a new battery, all is well.

K3WE wrote:

good_w2 wrote:
...Everything else works; i.e. lights..., turn signals, breaks etc. But, the battery isn't getting a charge. Really frustrating when I stop somewhere and no 12v power.

I am reading these comments different from most everyone else.

What do you mean "the lights work"? The lights INSIDE of the camper?

...and then you say you stop and there's no 12V power.

These two comments are suspicious- and make me ask "is your battery in the camper connected?"

For most of us, when we stop, there's 12V power because it's fed from the camper battery.

AND, if the inside lights work when the truck is on- then there IS 12V getting to your camper (and making it everywhere BUT the battery).

The tow vehicle has no 12V wire for the battery THAT IS SEPARATE FROM the 12V wire to power "everything" else in the camper (inside stuff).

Maybe you have said something wrong- but from what I quote you on, it's possible the tow vehicle is fine and the problem is with the camper.

(By the way 1- If you have some sort of battery disconnect switch, you disconnect it from charging)

(By the way 2- Folks often "lecture" that the TV does a bad job charging a battery- it does take a good while)

(By the way 3, If I'm right, you are most likely in a dangerous scenario where your brakes won't work if a breakaway occurs (Important safety feature for others)).

If your RV battery is charged and you do not have lights look for a battery disconnect and make sure it's on, has to be on for the battery to charge as well.

It also appears that the charge wire is only energized (somehow) when the tow/haul button is on or when the headlights are fully on (not just the DRL's)...it is not a constant hot 12V.

May be true for OP truck but not for my 2008 with dual batteries.
My trailer battery will go dead in 2 days when not plugged in. Hook up the truck and everything is fine, including slides and jacks.

K3WE wrote:

good_w2 wrote:
...Everything else works; i.e. lights..., turn signals, breaks etc. But, the battery isn't getting a charge. Really frustrating when I stop somewhere and no 12v power.

I am reading these comments different from most everyone else.

What do you mean "the lights work"? The lights INSIDE of the camper?

...and then you say you stop and there's no 12V power.

These two comments are suspicious- and make me ask "is your battery in the camper connected?"

For most of us, when we stop, there's 12V power because it's fed from the camper battery.

AND, if the inside lights work when the truck is on- then there IS 12V getting to your camper (and making it everywhere BUT the battery).

The tow vehicle has no 12V wire for the battery THAT IS SEPARATE FROM the 12V wire to power "everything" else in the camper (inside stuff).

Maybe you have said something wrong- but from what I quote you on, it's possible the tow vehicle is fine and the problem is with the camper.

(By the way 1- If you have some sort of battery disconnect switch, you disconnect it from charging)

(By the way 2- Folks often "lecture" that the TV does a bad job charging a battery- it does take a good while)

(By the way 3, If I'm right, you are most likely in a dangerous scenario where your brakes won't work if a breakaway occurs (Important safety feature for others)).

As I was falling asleep last night I was thinking the same thing as you. Something doesn't sound right in the OP's post.

to the OP,

Do you have a wire connected at stud near fuseblock under hood as needed? Does it have 12v? trace that wire to the 7 pin connector, does it have voltage? if it does, check trailer wiring (including ground), if not, check the wire between the stud under the hood and the 7 pin connector at the back of the truck.

If you don't have these skills, then you will need to find a friend that does or open your checkbook or ignore the problem.

Iraqvet05 wrote:
From the 2009 Silverado manual page 4-79.

"The fuse for
the battery feed is not required if the vehicle has
an auxiliary battery. If the vehicle does not have an
auxiliary battery, have your dealer/retailer or authorized
service center install the required fuse.
If charging a remote (non-vehicle) battery, press the
tow/haul mode button located at the end of the
shift lever. This will boost the vehicle system voltage
and properly charge the battery. If the trailer is too light
for tow/haul mode, turn on the headlamps as a
second way"

I'm assuming since the OP has a Duramax there is a second battery installed and the fuse is not needed like it is with the gas engine Silverados. It also appears that the charge wire is only energized (somehow) when the tow/haul button is on or when the headlights are fully on (not just the DRL's)...it is not a constant hot 12V.

It provides voltage without the tow/haul engaged, but engaging tow/haul or turning on headlights will signal computer to provide higher voltage from alternator, improving chances of high enough voltage and current to reach the trailer battery and make a difference.

good_w2 wrote:
...Everything else works; i.e. lights..., turn signals, breaks etc. But, the battery isn't getting a charge. Really frustrating when I stop somewhere and no 12v power.

I am reading these comments different from most everyone else.

What do you mean "the lights work"? The lights INSIDE of the camper?

...and then you say you stop and there's no 12V power.

These two comments are suspicious- and make me ask "is your battery in the camper connected?"

For most of us, when we stop, there's 12V power because it's fed from the camper battery.

AND, if the inside lights work when the truck is on- then there IS 12V getting to your camper (and making it everywhere BUT the battery).

The tow vehicle has no 12V wire for the battery THAT IS SEPARATE FROM the 12V wire to power "everything" else in the camper (inside stuff).

Maybe you have said something wrong- but from what I quote you on, it's possible the tow vehicle is fine and the problem is with the camper.

(By the way 1- If you have some sort of battery disconnect switch, you disconnect it from charging)

(By the way 2- Folks often "lecture" that the TV does a bad job charging a battery- it does take a good while)

(By the way 3, If I'm right, you are most likely in a dangerous scenario where your brakes won't work if a breakaway occurs (Important safety feature for others)).

""I'm assuming since the OP has a Duramax there is a second battery installed and the fuse is not needed like it is with the gas engine Silverados. It also appears that the charge wire is only energized (somehow) when the tow/haul button is on or when the headlights are fully on (not just the DRL's)...it is not a constant hot 12V. ""

Yes, my truck (Duramax) has 2 batteries. I'm pretty sure the hot wire is hooked up to the correct stud as I watched 2 different guys from the RV shop check it for the correct connection. They seemed to know right away what to look for.

I know there is a button at the end of the gear shift that sets the tow/haul, but I don't think it make a difference regarding getting power back to the plug/battery on the RV. I'm not sure. I will have to try that. It seems like the hot wire from the battery is a direct shot and not sure if there is a relay in between somewhere.

The RV tech in Tucson thought about the DRL as well and had me turn on the head lights when checking for power at the plug, so it didn't seem to make a difference. I will double check that.

From the 2009 Silverado manual page 4-79.

"The fuse for
the battery feed is not required if the vehicle has
an auxiliary battery. If the vehicle does not have an
auxiliary battery, have your dealer/retailer or authorized
service center install the required fuse.
If charging a remote (non-vehicle) battery, press the
tow/haul mode button located at the end of the
shift lever. This will boost the vehicle system voltage
and properly charge the battery. If the trailer is too light
for tow/haul mode, turn on the headlamps as a
second way"

I'm assuming since the OP has a Duramax there is a second battery installed and the fuse is not needed like it is with the gas engine Silverados. It also appears that the charge wire is only energized (somehow) when the tow/haul button is on or when the headlights are fully on (not just the DRL's)...it is not a constant hot 12V.

Just to confirm, there are two studs at the fuse box, you need the wire to be connected to the stud on the left as you stand at the front of the truck. The wire that is connected at the stud, IS the wire that runs back to the hitch. This is pretty simple....check for power at the stud....if you have power, trace that wire for a break or run a new one!