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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #1 · (Edited)
I have a 2007 lbz and I can not get the front axle to engage when I try to put it into 4hi or 4lo. The 3 button switch on the dash flashes when it's in 4hi and 4lo and it will pop up the service 4 wheel drive light. The 2wd light is solid. I can hear the transfer case motor shift. I have so far cleaned the body ground by the drivers door, replaced the front actuator, replaced the push button switch. I can hear the front actuator but it will not move. I have also done an ohm test on the 4 wires from the actuator to the connector on the wheel well liner and then from that connector to the transfer case control module. All the wires are showing very little to no resistance.
 

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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #2 ·
So quick update, I bought a different code scanner and pulled a c0379 only when I try to engage 4hi or 4lo. My front actuator is brand new and is functional when I tested it. The wire harness from the front actuator all the way to the tccm are still good. I have completely rerouted the 3 wires that were on that body mount now.
 

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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #3 ·
Just did a little more testing on my push button 4wd selector and I'm getting some resistance on the bule with plugged into the switch and also unpluged. When I push the button for 4hi it shows OL with it plugged into the switch. Would the switch be bad? I'm at a loss and not sure where to look next.
 

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1,159 Posts
Are you in gear when you're trying to switch it? Maybe something just isnt lining up perfectly on the inside.

I remember on my trailblazer the actuator sent power to a shift fork. The fork used to crack on people alllllllll the time. Bitch of a repair too. I would assume our trucks are different but I wonder if its something comparable
 

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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #5 ·
I have tried it in park and neutral. I'm thinking that I have an issue with the blue wire. I tested the resistance again on the switch unplugged and it's in the good range. When I hooked up my DMM to the blue wire and to ground I'm still getting voltage when I try to engage the 4wd. I thought the blue wire ground out after putting it into 4wd?
 

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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #6 ·
Here is a video of what is going on. Maybe this will help.

 

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2007 chevy 2500hd classic 6.6 lbz
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6 Posts
Discussion Starter · #7 ·
In 2wd the brown wire is 11.66v and the blue wire is 14v. In 4hi brown wire stays at 11.66v and the blue wire drops to 13.8v. Could this be a sign of a faulty tccm?
 
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