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Chevy Truck Question - 4x4 Actuator Wiring

kingOFgEEEks

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Good morning gearheads.

I'm stumped with this one, and need more ideas of what to be checking.

My 2011 Chevy 2500 HD isn't working right - the 4x4 actuator isn't engaging when I shift into 4x4. The truck is a 2500 WT with the 4x4 shifter on the floor.

What I've checked so far:

- 4x4 shift lever IS engaging the transfer case (front driveshaft can't spin when engaged, can spin when not)
- All fuses in the truck tested good
- Installed new 4x4 actuator
- I tested the wires on the actuator - ground has continuity. red wire has 12v when key is on, at all times.

There are 2 more wires on the actuator - tan/white and blue/white. Neither of these wires has power at any time - key on or off, 4x4 lever in 2wd or 4wd doesn't matter.

Where's my next look. I tried to trace the other two wires, but lost them in the wiring harness, but I can keep at it if that's the right thing to do.


Thanks!
 

5155

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Had a similar clusterflop on a 91. It was a NEW BAD actuator.
Took it back, they tested it on a car battery, said yep new part is junk.
Good luck.

I been through 4 of those in my time. I don't think they like creek water.
 

redline4

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Good morning gearheads.

I'm stumped with this one, and need more ideas of what to be checking.

My 2011 Chevy 2500 HD isn't working right - the 4x4 actuator isn't engaging when I shift into 4x4. The truck is a 2500 WT with the 4x4 shifter on the floor.

What I've checked so far:

- 4x4 shift lever IS engaging the transfer case (front driveshaft can't spin when engaged, can spin when not)
- All fuses in the truck tested good
- Installed new 4x4 actuator
- I tested the wires on the actuator - ground has continuity. red wire has 12v when key is on, at all times.

There are 2 more wires on the actuator - tan/white and blue/white. Neither of these wires has power at any time - key on or off, 4x4 lever in 2wd or 4wd doesn't matter.

Where's my next look. I tried to trace the other two wires, but lost them in the wiring harness, but I can keep at it if that's the right thing to do.


Thanks!

I will get you a wiring schematic and trouble chart a bit later once I get to work.
 

sawnami

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Did you check your shift fork and collar?
5661b991423d5b7b74f74b75b432942c.jpg
17410a3b3fb7857cbaa37145510c3e6f.jpg


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ktmtigger

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I just had an 08 in the shop for the same thing. Turned out to be the tccm. The t case has its own computer and gets stuck in sleep mode I pulled the fuse under the hood for it. Then put it back in and working fine for a week now

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ktmtigger

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I went through every part of that stupid system before I googled it and it showed the tccm gets stuck in sleep mode

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redline4

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Thanks guys! That's what I'll check next. I'll re- check the TCCM fuse and leave it out for a few minutes to be sure, then test that wire.

I knew y'all would have the answers for me!
Which transfer case do you have? If you have the manual lever on the floor, there is no transfer case control module...
 

kingOFgEEEks

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It's the floor shifter, so no TCCM? What powers the 4x4 actuator when I shift?

I miss lockout hubs and everything being mechanical.
 

redline4

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The actuator is supplied constant voltage. It gets its ground to activate it through the switch on the t-case.
 

kingOFgEEEks

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The actuator is supplied constant voltage. It gets its ground to activate it through the switch on the t-case.
I see. So, the other two wires should be going back to the t-case, and when the lever is pulled back, they connect the circuit there, engaging the actuator?
 

redline4

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I see. So, the other two wires should be going back to the t-case, and when the lever is pulled back, they connect the circuit there, engaging the actuator?

Basically, yes. It will close the switch, giving a ground to the "logic" part of the actuator.
 

kingOFgEEEks

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View attachment 208218

If the light doesnt illuminate, its either the switch on the t/case or wiring.
I got a chance to work on it tonight. I traced some things around, and cut the grey wire and temporarily spliced it to ground. The actuator worked. It looks like the switch to me, so once I get a new one, I should be in business.

Am I right in looking at that transfer case switch, that it should be powered in 2 wheel drive, and when I shift to 4 wheel drive, it grounds out?

Thanks again for pointing me in the right direction.
 

redline4

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I got a chance to work on it tonight. I traced some things around, and cut the grey wire and temporarily spliced it to ground. The actuator worked. It looks like the switch to me, so once I get a new one, I should be in business.

Am I right in looking at that transfer case switch, that it should be powered in 2 wheel drive, and when I shift to 4 wheel drive, it grounds out?

Thanks again for pointing me in the right direction.

Yes and no. One side of the transfer case switch is simplyva ground path.
The other side receives a reference voltage from the ECM, which is pulled low when the switch is closed to tell it 4wd is engaged.

Yes, if you ground that circuit and the actuator engages, the fault is either the switch or the wiring "beyond " where you cut it.. and at least use a heat shrink connector to repair that
 

kingOFgEEEks

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Yes and no. One side of the transfer case switch is simplyva ground path.
The other side receives a reference voltage from the ECM, which is pulled low when the switch is closed to tell it 4wd is engaged.

Yes, if you ground that circuit and the actuator engages, the fault is either the switch or the wiring "beyond " where you cut it.. and at least use a heat shrink connector to repair that
Perfect. And yes, my brother who was a USAF aircraft maintainer did a good heat shrink splice for me.
 
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