- #9 of 90
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Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
by repairdog
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Dec 10, 2006 (3:03 am)
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Replying to: johnnyd69 (Dec 09, 2006 10:18 am)
Which part the encoder motor? Is this a 3 button dash switch? Problem depends on case type and exact area and did a GM dealer work on it?
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- #10 of 90
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Re: 2003 Chevy Blazer recurring 4wd problem [repairdog]
by johnnyd69
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Dec 10, 2006 (10:02 am)
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Replying to: repairdog (Dec 10, 2006 3:03 am)
It is a 3-button dash switch, and each time a GM dealer has worked on it; they've replaced the unit each time.
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- #11 of 90
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Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
by
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Dec 10, 2006 (1:13 pm)
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Replying to: johnnyd69 (Dec 10, 2006 10:02 am)
If they are just changing the dash switch thats why it keeps craping on you - there is a vac line to the transfer case 3 port switch that the encoder motor for 4HI directs vac to the front actuator and engages the front driveshaft. Sensors tell the TCCM (4wd computer) status and allows all to occur. 4Lo then has the encoder motor further engage the low gear. Someone isn't finishing the complete fix.
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- #12 of 90
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Re: 2003 Chevy Blazer recurring 4wd problem []
by johnnyd69
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Dec 11, 2006 (10:21 am)
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Replying to: unknown (Dec 10, 2006 1:13 pm)
Actually, they've replaced the switch as well as the transfer case (which is always the problem). When it's gone on me it has made a grinding noise and then it gets stuck in 4WD (as it is now). It seems to happen when it's cold; I live in the Northeast and need the 4WD for winter, so this is a huge problem. I'm just wondering if anyone has heard of this being a chronic problem, i.e. that the transfer case units are junk. I'm thinking they are, since this has happened to me 3 times in 4 years, two of them when I really needed the 4WD (in major snow storms). I'm thinking that it's time to let this car go at the end of lease and get something reliable.
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- #13 of 90
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2003 Chevy Blazer - SAME 4wd problems too!
by watertank
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Feb 02, 2007 (2:42 pm)
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I had mine into the dealership (full extended warranty  ) last week. Thumped into 4hi on the fly and stuck. Got it back out in neutral only to have it stuck there. They changed the transfer case control module. Switched to 4hi once then tried on the morning I needed it. Tried in neutral moving, neutral still, in gear and both 4hi and 4lo lights would only blink at me. Then in the parking lot in neutral I tried again to go into 4hi and it thumped into 4lo. Ok enough of that.
Back to the dealership. They called and said my battery wasn't good enough to engage the motor (my volt meter never wavered...seemed to hold a charge ok). I said go ahead and replace it. They called back and said there was another problem with the encoder motor.....they are in the process of replacing that now. Seems to me diagnostics would have shown that right away. I questioned the need for a new battery but not having tested it myself have to succumb.
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- #14 of 90
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Re: 2003 Chevy Blazer - SAME 4wd problems too! [watertank]
by repairdog
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Feb 02, 2007 (3:18 pm)
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Replying to: watertank (Feb 02, 2007 2:42 pm)
Yep, they were winging it. How much for that Delco battery - ask them to put the original back if that wasn't the problem or just pay it (only battery cost as that was NOT the problem you brought it in for and did not fix it - but you're a good guy so ....) As for a 2003 encoder motor if you are in a wet salt use state thats possible and that was free so ... sounds good if it now works.
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- #15 of 90
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Re: 2003 Chevy Blazer - SAME 4wd problems too! [repairdog]
by watertank
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Feb 02, 2007 (3:27 pm)
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Replying to: repairdog (Feb 02, 2007 3:18 pm)
They just called and said with the new encoder motor, they still can't get it to go into 4hi (just 4lo). I gave them some info from here, wiring harness and vacuum line and they said that's where there going next. They also said the battery failed on the diagnostics........I'm on my way over to get a loaner. Thanks for the forum and the info. Will keep you posted.
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- #16 of 90
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Re: 2003 Chevy Blazer - SAME 4wd problems too! [watertank]
by repairdog
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Feb 03, 2007 (4:19 am)
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Replying to: watertank (Feb 02, 2007 3:27 pm)
I looked back and never saw if this was a 3 or 4 button dash switch - 4 is Autotrac case. If it went into 4Lo then the front axle coupler worked. 3 button np233 case the encoder steps once to 4HI and sends vac to front actuator via a 3 port vac switch on the case and engages the front drive shaft. Steps again for 4Lo.
Autotrac np 236 case is different and front driveshaft always on. For 4Hi you have a firewall solenoid that the TCCM energizes to supply vac to the front actuator and the encoder only steps for 4LO.
Would look at TCCM,dash switch, 3port or firewall solenoid (by type) or a cut wire/loose connector. First I hope they tried to reset the TCCM by removing power for 30 minutes.
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- #17 of 90
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2004 Blazer 4wd problem
by 2004blazer
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Feb 08, 2007 (2:46 pm)
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Sounds like the same problem I am having with my 2004 Blazer. It will go into 2 hi and 4 low the lights will blink but WILL NOT go into 4 hi. Chevy dealership stated that I had to put it on the computer to find out what the exact problem is. ANYBODY KNOW WHAT IT IS AND HOW I CAN FIX IT WITHOUT SPENDING A FORTUNE ?
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- #18 of 90
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Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
by grose67
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Jul 25, 2007 (9:38 am)
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Replying to: johnnyd69 (Dec 08, 2006 9:36 am)
I had the type of issue happen on my 95 Blazer. What I found was a kink in the vacum line. Once that was fixed, the 4 wheel drive worked great and has ever since. That was two years ago.
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