NEED HELP 07 Trailblazer Trasfercase issue?

Buzzstpoint

Member
Been having an issue with my 4wd. Flashing selector switch, and 4wd service light.

Been through 4 different transfercase motors. All seemed to do a different issue. Flashes and stick in 4 high, or flash and stick in auto.. After checking wiring and replacing switches, actuator and tccm. Nothing has fixed my 4wd problems.

So while under the truck I fired it up and tried to turn the shaft where the transfercase motor bolts on, the shaft will turn clockwise about an 1/8 turn and spring back. If I go counter clock wise it will turn a little more then 1/8 and stop. Doesnt want to engage in to 4hi or lo.

Unless I'm doing something wrong, do I see a transfercase in my future?
 

Mooseman

Moderator
What has the maintenance of the TC been like? The fluid should be changed every 50k miles, which is a relatively short period. When you drain the fluid, check for bits of metal.

With the encoder motor off, how does it move when you move the selector? Does it turn?
 

budwich

Well-Known Member
not sure that "firing up" and trying the turn by hand is valid.... depending on what position the transfer case actually is in.
 
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Buzzstpoint

Buzzstpoint

Member
What has the maintenance of the TC been like? The fluid should be changed every 50k miles, which is a relatively short period. When you drain the fluid, check for bits of metal.

With the encoder motor off, how does it move when you move the selector? Does it turn?
I bought the TB 2 years ago, dealership said they changed all fluids on the truck.. I put on about 30k already, currently sitting at 195k on the truck.

With the encoder off the motor will turn.
On the case it will small buzzing sounds about 2 second apart for a short time then stop.
 
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Buzzstpoint

Buzzstpoint

Member
not sure that "firing up" and trying the turn by hand is valid.... depending on what position the transfer case actually is in.
I thought if the truck was running , if I turn by hand, I may be able to determine if the transfer case has an internal problem.
 

seanpooh

Well-Known Member
By any chance you scan for codes? It helps.

Draining the transfer case would aid in identifying if anything is wrong internal, but not all the time. Where did you obtain the four different encoder motors?

To get into 4LO you have to be in neutral and engine running.
 
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budwich

Well-Known Member
who installed the encoder(s)? how were the encoder(s) installed? Is the truck currently "motive"?
 
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Buzzstpoint

Buzzstpoint

Member
By any chance you scan for codes? It helps.

Draining the transfer case would aid in identifying if anything is wrong internal, but not all the time. Where did you obtain the four different encoder motors?

To get into 4LO you have to be in neutral and engine running.
I'll have to wait a couple of weeks before I have time to change the fluid.
As far as the encoder motors, 1 is orginal, 2 junk yards, and 1 remaned from my work.

I'll scan the codes in the morning.
 

budwich

Well-Known Member
OK... have you scanned / are you able to scan for codes.... note: they are not likely P codes but C codes. IF not, you then need to get a meter out and verify the electrical conditions are the connector of the motor / transfer case.
 
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Buzzstpoint

Buzzstpoint

Member
Sorry for the delay... work is just kicking me and inky have every other weekend off.

But new developments.
The transfercase decided not to work anymore. Horrible grinding sound.
I swapped the transfer case with a used one. But the 4wd still doesnt work.

It's been in the shop for 2 weeks. A buddies shop that was trying to help me out in the spare time. So far he narrowed down there is only 9v going to the encoder motor. I picked up the truck tonight.

That's as far as we got. Hopefully I'll get some time to look at it this weekend and see if I can narrow it down.
 

Mooseman

Moderator
What year is your truck? The TCCM in 02 and some 03 had defects but it would be evident with the selector lights flashing and the service 4wd light coming on.

So what does it do? Does it drive in 2wd? What happens when you move the selector?
 
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Buzzstpoint

Buzzstpoint

Member
I have 2007 trailblazer LT

It's in 2wd, and yes you can drive it just fine..
If I pull the fwd fuses for a few minutes.
I can flip the selector switch to 4HI, turn the key on and the selector switch will flash, then jump to Auto. But it will not got back to 2hi. Only way to get it back to 2hi is repeat this process with the selection on 2hi.

*before the transfercase swap. Here were the codes in the truck.
C0455 - history code
U1000 - history code
U1026 - history code
C0306 - history code
C0321 - current code
C0326 - history code
C0379 - current code
P0420 - current code
 

budwich

Well-Known Member
the "9v" going to the motor isn't going to help the motor turn properly. That would appear to indicate a wiring issue which needs to be traced back to the source... assuming that the measurement was done correctly.... you measure voltage from the test point back to a KNOWN good ground.... if you don't follow this procedure, then the measurement is "unreliable" in that the "reference point" ("fake ground") may also be the issue.
 

TJBaker57

Well-Known Member
C0379 - current code
In the first post of this thread you state you replaced the "actuator". Typically the term actuator is used to refer to the FRONT axle disconnect actuator. The current code C0379 code refers to this apparatus. I sort of skimmed through this thread and didn't see any more talk of front axle disconnect, might have missed it though. Have you in fact replaced this item or were you speaking of the transfer case encoder/motor assembly?
 
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Buzzstpoint

Buzzstpoint

Member
In the first post of this thread you state you replaced the "actuator". Typically the term actuator is used to refer to the FRONT axle disconnect actuator. The current code C0379 code refers to this apparatus. I sort of skimmed through this thread and didn't see any more talk of front axle disconnect, might have missed it though. Have you in fact replaced this item or were you speaking of the transfer case encoder/motor assembly?
Sorry, when I was saying actuator, I was referring to the tcase encoder motor.
I'm hearing the garage and going to start testing wires to see where he found the 9v the trace back.
 

TJBaker57

Well-Known Member
So then you also have a current code for the front axle disconnect which needs investigation and resolution before the 4wd will be functional even if the transfer case shifting is resolved.

In a nutshell, if the front axle disconnect engages properly, no single shaft (left front wheel, right front wheel, or front driveshaft) should be able to be turned without a second shaft also turning. Most often recommended test is shift to 4wd (not likely to work in your case) then jack up ONE front wheel and see if it will turn.
 

jmonica

Well-Known Member
Hate to hijack but how did you install your TC? Did you lift it up yourself to install it? I'm stuck at this point and too f'ing weak to lift it into place myself I'm ashamed to say. Thank You
 
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Buzzstpoint

Buzzstpoint

Member
I was under my truck for 3 hours trying every I could to get that beast in.
2 people and brute force I how I ended getting it in. Had my wife grab the front output shaft and lift while I lifted the passenger side. We got it slid in there in less then 5 minutes.
 

jmonica

Well-Known Member
I was under my truck for 3 hours trying every I could to get that beast in.
2 people and brute force I how I ended getting it in. Had my wife grab the front output shaft and lift while I lifted the passenger side. We got it slid in there in less then 5 minutes.
Hey! I just wanted to say Thank You for your reply. I feel so inept and useless because I couldn't get the thing up there on my own. I can lift it when I am not under the car on my back but not using just my minimal arm strength. I've been trying to get back to it for two weeks now, but haven't had a day of in weeks to try the ratchet strap method I have planned. Anyway, thanks again and Happy Holidays!
 

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