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TCBCK
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567 Posts
Discussion Starter · #1 ·
What are the common problems with 2000 GMC sierra Z71 4WD? I was driving to the beach and the light just came on and hasn’t went off, been about 4 days now. I checked the fluid which was somewhat low. Should I restart the computer since it needed fluid and see if that was it? Are these trucks so smart that if the fluid in t-case is low it will show SERVICE 4WD light? Last time I used the 4wd it worked fine no problems so what do yall think? Thanx for any help....W/F
 

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TCBCK
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567 Posts
Discussion Starter · #2 ·
Someone has got to know something on this issue, am I the only z71 4x4? :think::think::think:
 

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VA Z71
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13 Posts
I have had the same problem for almost a year now. The light started to come on again after a few months...I have no idea what the problem is. Everytime I want to take the truck in to hook the computer up and find the problem the light goes away, go figure! If you find out anything let me know!
 

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Resident Guinea ***
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14,535 Posts
Sounds like a communication glitch. Occasionally the data bus these trucks use to transport data from the various sensors and actuators throughout the vehicle becomes congested.

If the warning message is no longer present, I wouldn't worry. You can go to Auto Zone/Advance Auto and have a diagnostic scan done for free. They use an OBDII scan tool to interface with the trucks PCM and it will retrieve any stored trouble codes. You can further troubleshoot from there if codes are present.
 

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QuadraSteernado
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8,385 Posts
I hear it's a problem with the 4wd button control unit.

It pops up on my cluster about 2 times a month and I just ignore it :jester:
 

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TCBCK
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567 Posts
Discussion Starter · #6 ·
Im going to restart the computer tonight and see what that does. The 4wd wont even work while that dam light is on, this shit sux dude. :pissed: I will let ya know if this works out.....W/F
 

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QuadraSteernado
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8,385 Posts
Im going to restart the computer tonight and see what that does. The 4wd wont even work while that dam light is on, this shit sux dude. :pissed: I will let ya know if this works out.....W/F
It's a problem with the buttons then

Mine doesn't work when I get the code.

Sometimes the unit will say I'm in 4lo when I'm in 2hi :rofljest:
 

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TCBCK
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567 Posts
Discussion Starter · #8 ·
It's a problem with the buttons then

Mine doesn't work when I get the code.

Sometimes the unit will say I'm in 4lo when I'm in 2hi :rofljest:

How many miles you got on urs? Mine well.....239,693!!!:eek: nothing bad has messed up just alt,starter,rear end, normal stuff. (knock on wood) Changed oil always and tranny fluid, still going strong. Will know in the morning about computer restart, if not then it may be the damn buttons :flame:
 

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63 Posts
the buttons usually mess up
it is easy to take out and resolder all the points on the board. U can usually see which ones are cracked.
If the switch seems ok try the ground wire below the drivers door by the body mount. I read that this causes loads of troubles with the 4wd system too. After these 2 checks then id look toward the encoder on the transfer case.
process of illimination will find the culprit.
 

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4,856 Posts
kenny had a similar problem. It turned out to be the electric module on the front diff. The piece where the electrical connector connects. Take a crecent wrench and unscrew it. Once its out, check to see if the pin is in. If its all the way out then that module is messed up. if thats the case swap in a new one and it should be good to go.
 

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TCBCK
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567 Posts
Discussion Starter · #12 ·
the buttons usually mess up
it is easy to take out and resolder all the points on the board. U can usually see which ones are cracked.
If the switch seems ok try the ground wire below the drivers door by the body mount. I read that this causes loads of troubles with the 4wd system too. After these 2 checks then id look toward the encoder on the transfer case.
process of illimination will find the culprit.
Damn thanks for the info man, Sounds like you know a lot about these trucks. Will do tomorrow for sure if the restart doesn’t work. :shake:
 

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TCBCK
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567 Posts
Discussion Starter · #13 ·

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TCBCK
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567 Posts
Discussion Starter · #14 ·
kenny had a similar problem. It turned out to be the electric module on the front diff. The piece where the electrical connector connects. Take a crecent wrench and unscrew it. Once its out, check to see if the pin is in. If its all the way out then that module is messed up. if thats the case swap in a new one and it should be good to go.

Kenny ever post any pics of the fix? Either the switch, ground wire, or electric module on front diff. got it. I hope one of these are it cuz Sunday I’m going to Davis landing with some buddies and getting muddied up Bro!
 

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VA Z71
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13 Posts
Mine has about 98,000 miles. The 4wd switch light goes dim and sometimes just doesnt light up. Yeah, I think it's just the selector going out. I heard thats a common problem. Gm parts direct has them for around 40-50 bucks.
 

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TCBCK
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567 Posts
Discussion Starter · #16 ·
Mine has about 98,000 miles. The 4wd switch light goes dim and sometimes just doesnt light up. Yeah, I think it's just the selector going out. I heard thats a common problem. Gm parts direct has them for around 40-50 bucks.
Damn I never heard of this site!!! Thanks for the heads up bro.... :cheers:
 

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TCBCK
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567 Posts
Discussion Starter · #17 ·
Oh by the way I did restart my computer last night. When I first cranked it up truck ran like shit for about 5 min. (guess it was re-learning) But the light did go off and now the 4wd works!!!! Im sure I still have some sort of a problem if the light comes back on. As for now Im good to go, all I did was put fluid in it cuz it was low then restarted computer
 

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VA Z71
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13 Posts
How did you restart the computer? Did you just add fluid in the front diff or both?
 

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TCBCK
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567 Posts
Discussion Starter · #19 ·
How did you restart the computer? Did you just add fluid in the front diff or both?
Put fluid in the diff. then before I went to bed disconnected the battery cable from battery. When I cranked it up in the morning before work it did run a lil rough but only for a few. That’s just the system is re-learning itself!!!! What going on with yours?
 

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VA Z71
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13 Posts
Well the other day I changed the fluid in the front and rear diff. so that is good. Im thinking that it's just a bad connection in the 4WD switch. I just need to bite the bullet and buy a new one...hopefully that fixes the problem.
 
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