Last post on Feb 12, 2012 at 1:46 PM
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Chevrolet Blazer, GMC Jimmy, Auto Repair, SUV
#6 of 115 2003 Chevy Blazer recurring 4wd problem
Dec 08, 2006 (8:36 am)
I have a 2003 2dr. Chevy Blazer and the 4wd just went for the third time (once a year for the past three years). Since I'm leasing it, it is being fixed free of charge, but my lease is running out in March and I have to decide whether or not to keep it (and won't if this is a chronic problem with the 4wd). Has anyone heard of this being a chronic problem (i.e. bad units being produced)?
#7 of 115 Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
Dec 09, 2006 (3:49 am)
All newer 4wd systems seem to have some quirks due to the move to shift on the fly smart systems. You never said what problems you had but if you read the posts most are small things that the owner can easily fix. Search other forums and see if your "next" vehicle has any problems. If not, then turn it in. The ZR 2dr was pretty good off road but not the best on road and the back seat is terrible so if any family now or planned dump it.
#8 of 115 Re: 2003 Chevy Blazer recurring 4wd problem 
Dec 09, 2006 (9:18 am)
Thanks! The problem I have had three times so far is: when I clicked the button to shift into 4WD from 2WD it made a grinding noise and then went dead (i.e. it was in 4WD high and I was unable to shift back into 2WD). Each time they've replaced the the unit and once the dashboard switch (although that has gone once as well). I was just wondering if anyone's heard of these 4WD units being defective. I love the truck otherwise and have not had one problem in 4 years other than this, but since I need the 4WD, if it is I'll dump it for something else.
#9 of 115 Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
Dec 10, 2006 (2:03 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?
#10 of 115 Re: 2003 Chevy Blazer recurring 4wd problem [repairdog]
Dec 10, 2006 (9:02 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.
#11 of 115 Re: 2003 Chevy Blazer recurring 4wd problem [johnnyd69]
Dec 10, 2006 (12:13 pm)
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.
#12 of 115 Re: 2003 Chevy Blazer recurring 4wd problem 
Dec 11, 2006 (9:21 am)
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.
#13 of 115 2003 Chevy Blazer - SAME 4wd problems too!
Feb 02, 2007 (1:42 pm)
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.
#14 of 115 Re: 2003 Chevy Blazer - SAME 4wd problems too! [watertank]
Feb 02, 2007 (2:18 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.
#15 of 115 Re: 2003 Chevy Blazer - SAME 4wd problems too! [repairdog]
Feb 02, 2007 (2:27 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.