# 2008 Chevy 2500hd ?



## Ray C (Apr 4, 2007)

I just got a 2008 Chevy 2500hd with the duramax and allison I was testing out the trailer wiring plug i found i have no 12 volts to the battery terminal on both the rear plug and the 5th wheel wiring. The manual said i need to add a fuse but there is a fuse in position 68 in the under hood fuse block. Is there something else I am missing or should i contact the dealer?


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## huntr70 (Jul 8, 2005)

Is it an actual fuse or a dummy??

I think I remember someone saying there is a dummy fuse in there that needs to be replaced.

Steve


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## nynethead (Sep 23, 2005)

There is a small red wire that is curled up next to the fuse box and it needs to be plugged in. the fuse is already in from the factory. My cousin just purchased an 08 3500 dually and he had the same problem 2 days ago. stopped by a dealer and they fixed it in 5 minutes and he was on his way.


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## MI Outback (Sep 24, 2007)

Take a look at this post...I did a similar write up but this one is way better.

http://www.outbackers.com/forums/index.php...amp;hl=suburban


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## Ray C (Apr 4, 2007)

After looking yesterday for a few hours trying to find any wires or missing fuses I contacted the dealer today. I got a service tech on the phone and he had a pickup in on friday with the same problem. Seems Chevy has added a third wire that has to be attached to the stud 2. The wire is in the main wire loom under the brake cylinder. He was able to talk me over the phone to exactly where the third wire was. He said that some time in 2008 models they added the third wire and didn't tell anybody. The owners manual says nothing about a third wire I read it many times yesterday.
Just for everybody to know just check that you have power to your plug on the batt. terminal.


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## malibutay (Sep 5, 2007)

Do you have the brake controerl that comes with the truck from the factory? This concerns me since I thought it would just work when I pluged into it with my tt.


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## Wolfpackers (May 31, 2007)

I have the 07 Silverado 2500HD, Duramax/Allison with the new body style, so presume it's identical to the 08 in regards to this topic. I too had the same discovery and found out that the wire below the brake cylinder is for use if you use an aftermarket brake controller. Not needed to hook up if you have the integrated brake controller. There is a second wire hidden between the fuse box and fender wall that needs to be connected to send 12V to the 7 pin plug for battery charging. The wires connect to the two studs at the front of the fuse box and each wire goes to the opposite stud, thus they will cross each other.

If I can find the link, I'll edit this and add it, but it shows photos with good detail and explanation of this setup.

Brent

Edit: here is the Link to the best explanation I've seen or heard yet and it has great photos. Unless you are installing an aftermarket brake controller, skip down to step 18 and start there.


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## Ray C (Apr 4, 2007)

malibutay said:


> Do you have the brake controerl that comes with the truck from the factory? This concerns me since I thought it would just work when I pluged into it with my tt.


yes i have the factory brake controller


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## luv2rv (Jun 21, 2004)

I had the same issue. The wiring is there ... why not simply make the connections at the factory when the truck comes with a tow package !!!!

Anyway, once hooked up the whole system works great brake controller and battery charger.

Wayne


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