06 Trailblazer 4wd failure to engage

RayP(MI) · Feb 7, 2018

Electrical engagement via dash mounted
switch. When tryingg to engage, switch in
any 4wd position will cause indicator
lights to flash, return to 2wd and throw a
"fix 4wd" code. Code translates to "replace
front differential actuator." So I had
mechanic replace it. Worked for a little
while and no back to working part time.
First time it failed, took it back to
mechanic in the morning. Sat outside his
shop until after lunch, and he could not
get it NOT to work. Now it fails
intermittently. Usually if is driven a bit
it will start working again. Thinking it
needs to be warmed up a bit to work.. Maybe
ice in front differential preventing it
from engaging? Anyone have similar
experiences? Appears all other functions of
4wd mechanism working OK

Paul Shuler · Feb 7, 2018

My 08 duramax truck has done the same. I changed my front diff oil and it was full of water. But it still did it after oil change. I have had to take the large fuse out under the hood and put it right back in and then it will work fine. I also have learned not to take it out of 4 wd if there is any stress on the drive line at all or it will do the same flashing thing. I will pull up to a flat place and let it roll a bit and it will come of just fine. Tried to take it out of 4 wd last fall while turning off of a muddy slippery road onto pavement and it would just flash and wouldnt come out of 4 wd. Found a flat gravel lot and let it roll a bit and it came right out. Hope this helps.

rrlund · Feb 7, 2018

Can't speak to the Chevy,but on Kim's Ford we had to step on the brake pedal,put it in neutral then turn the switch. That's how my F250 works too when trying to get it out of 4 wheel low.

dpendzic · Feb 7, 2018

I had to have my 08 actuator replaced and its working fine---when was the last time you changed the front differential oil?

mj · Feb 7, 2018

(quoted from post at 13:53:03 02/07/18) My 08 duramax truck has done the same. I changed my front diff oil and it was full of water. But it still did it after oil change. I have had to take the large fuse out under the hood and put it right back in and then it will work fine. I also have learned not to take it out of 4 wd if there is any stress on the drive line at all or it will do the same flashing thing. I will pull up to a flat place and let it roll a bit and it will come of just fine. Tried to take it out of 4 wd last fall while turning off of a muddy slippery road onto pavement and it would just flash and wouldnt come out of 4 wd. Found a flat gravel lot and let it roll a bit and it came right out. Hope this helps.

A 4x4 will build torsional stress between the front and rear axles which is noticeable when trying to make a sharp turn or when trying to shift out of 4wd. The 'bind-up torque' won't allow you to shift the transfer case without relieving the torque. BACKING-UP, to relieve this torque IS STANDARD PROCEDURE IN THIS PART OF THE COUNTRY. I'll bet that your manual recommends this procedure.

RayP(MI) · Feb 7, 2018

This transmission allows 2WD, 4 Auto, 4WD shift on the go. 4 LOW requires less than 2mph, and transmission in neutral.

GordoSD · Feb 7, 2018

Can you get it into heated shop overnight? Then do some tests? Look for white fluid in there which is water.
Also double check the part number of the new actuator. There are several for that model and he may have the wrong one in there. Ford dealer put a Explorer actuator in y 150 an it didn't like that at all.

rrc300 u · Feb 7, 2018

I can't say for sure but I bet it works the same. My 05 Chev had the 4 4low 2wd or auto 4 function. I left it in auto almost bthe entire life of that truck. The only time I ever took it out was on a trip to my brothers house(220 miles) I ran it one way in auto and the way back in 2wd and saw no change in mileage. I only ever had that thing in 4 hi a handful of times. I live in the sticks in nwpa, we get serious snow. I think auto mode kept it all excerxised year round.

big daddy · Feb 7, 2018

I HAVE had trouble with my 05 sliverado, same problems , my mechanic replaced a sensor on both front wheel hubs , seems to have fixed it so far, but I will keep my fingers crossed, I hate all the new electronic devicves

omahagreg · Feb 7, 2018

On our 02 Trailblazer, it was doing that exactly. Found there was a TSB (technical service bulletin) about that. It stated that you were to remove the 30 amp fuse for the traction control out of the panel under the hood for 30 seconds and then reinstall. Ours worked after doing that for several years, and then it did not...! Our mechanic said it was not worth throwing money at it, as he had worked on a Suburban once. He had $1300 in it, with it still not working, owner took it to Chevy, spent another $1300 before it worked. So, we owned a 2wd, rear wheel drive Trailblazer for almost 4 years!

showcrop · Feb 8, 2018

The clutch packs in any of those transfer cases need not just good and correct oil to work properly, it needs to be within the change spec. I had a new to me Explorer that was just three years old but high miles, that started to hop when turning sharply. All it took to fix it was new oil. If the packs don't slip as they are supposed to it keeps your actuator loaded.

06 Trailblazer 4wd failure to engage

RayP(MI)

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Paul Shuler

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rrlund

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dpendzic

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mj

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RayP(MI)

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GordoSD

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rrc300 u

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big daddy

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omahagreg

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showcrop

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