Dual Battery not charging

[M60A3MG]

I have a 2011 Sierra 2500 HD with 6.0L. I bought it from the original owner. It has the Factory Dual Battery setup. I started noticing a problem with My snowplow and then the external Jumper cables, Both of which are connected to the Secondary Battery. I had Replaced Both batteries with New ones thinking one of the batteries were older and I just like to make sure I always have a good battery.

 

a couple months after replacing them I noticed a problem I was having with a Ham Radio that I just ran a power line from the secondary battery. I ended up putting a meter on the second battery and got about 10 Volts. The Primary is 12V when sitting and 14V when the engine is running. So traced the wire from the primary to the secondary and identified the solenoid / coil "part number 12135194" that keeps the battery separate when the truck is not running so the primary won't get drained.

 

On the solenoid I have 14V on the primary battery side and 10V on the secondary side with engine running. This made me believe the solenoid was bad and not opening to allow the 14V to pass through to the secondary. Only $60 so not bad.

 

Problem is I still don't get the 14V being passed through the solenoid. The next part I'm looking at is a Relay 21997407

 

Am I barking up the wrong tree or Is there something I should check first??

 

 

[M60A3MG]

The Voltages are rounded off

[bgbdwlf2500]

If it were me if run a new power wire from the main to the secondary and bypass the solenoid altogether. You can add one later of need be

[anumber1]

Clean the connections! That ground looks terrible in the picture...

[last truck]

I have replaced more than a couple of the solenoids on the firewall, I would make sure it is getting power on the small wire while running and it it is then replace the slenoid.

Edited September 25, 2016 by last truck

[M60A3MG]

I already replaced the solenoid, I didn't know it was grounding where it is bolted to chasis, Also The 2 small wires the connect to solenoid, will just one be positive or both especially if it is grounded through the mounting?

 

I prefer to keep the solenoid as I like the idea that if I run down the Aux battery , I still have power on the primary to start.

 

I have been looking for schematics but no luck,

[sdeeter19555]

I would replace, or at least test, that relay...you should get 14v at at least one of the trigger terminals on the solenoid from the relay. That solenoid is likely externally grounded, meaning one of the small terminals is positive and the other is a ground. At least one should have 14v to operate.

 

Also check your grounds...

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Cosmic Charlie]

On my 11 HD the second battery was for the trailer ... OEM from the factory

 

When my starting battery got weak the other battery was was just sitting there charged and I had to use a jumper cable from the that battery to my starting battery ... my 2015 HD is the same way

 

2 separate systems so the 2nd battery does nothing for the snow plow set up ... or anything else except related to the trailer

 

I believe they are not linked in any way except the solenoid between makes sure they charge separately

 

read up on it

 

If I'm wrong I want to hear ... not really clear to me

[last truck]

I already replaced the solenoid, I didn't know it was grounding where it is bolted to chasis, Also The 2 small wires the connect to solenoid, will just one be positive or both especially if it is grounded through the mounting?

 

I prefer to keep the solenoid as I like the idea that if I run down the Aux battery , I still have power on the primary to start.

 

I have been looking for schematics but no luck,

 

It isn't grounded thru the base one small wire will be 12 volts with engine running other small one will be ground.

 

Page A12

https://www.gmupfitter.com/files/media/photo/482/2011_LD_ElectricalPickupsChassisCabs_100813.pdf

Edited September 27, 2016 by last truck

[intheburbs]

On my 11 HD the second battery was for the trailer ... OEM from the factory

 

When my starting battery got weak the other battery was was just sitting there charged and I had to use a jumper cable from the that battery to my starting battery ... my 2015 HD is the same way

 

2 separate systems so the 2nd battery does nothing for the snow plow set up ... or anything else except related to the trailer

 

I believe they are not linked in any way except the solenoid between makes sure they charge separately

 

read up on it

 

If I'm wrong I want to hear ... not really clear to me

 

Well, I did the TP2 dual battery install in both of my trucks. I used factory GM parts, so everything works as if the TP2 option was checked when the vehicles were built.

 

If you trace the wires from the positive cables of both batteries, you should see that they eventually are joined by the bus bar on the mega fuse holder on the passenger side of the firewall.

 

Now, if you have a fuse in location 68/stud 1 in the underhood load center, that fuse basically parallels the batteries to power the trailer plug. So that fuse needs to be pulled to truly isolate the batteries when the ignition is off. Not sure if that's changed from on the K2XX platform.

 

Here's where the two batteries are electrically connected at the mega fuse holder:

Edited September 27, 2016 by intheburbs

[M60A3MG]

On Mine whomever installed the Plow and front grille jumper cable system wired them to the Aux Battery probably cause it was closer.

 

The PDF with the schematic was helpful. I believe my fuse holder is on top of the main battery though.

 

I will check out replacing the relay next

[Thomas Mulder]

Did replacing the relay fix this problem?