Flashing 4wd switch lights - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 5.3L V8 Engine and Drivetrain > 4x4 Drivetrain

4x4 Drivetrain 4x4 Repairs & Problems

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  #1  
Old 02-06-2010, 08:38 PM
kip45223 kip45223 is offline
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2005 Chevy TrailBlazer LS
White 4.2L I6 4X4
Join Date: Jan 2010
Location: Hamilton, OH
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Flashing 4wd switch lights

Last year when it got cold my 05 Traillazer LS started having issues. When it got cold and snowy, the 4wd switch lights would all flash when the car was started and then go to the 2hi or whatever was selected and that light would flash then after 15-20 flashes all lights go out and have no ability to use the 4wd. The weather broke in 2 days and all was good until it got cold and snowy this month and it started again. I finally broke down and took to dealer. Was diagnosed as the actuator on the front axle.......replaced. this did not fix it. They replaced a spider gear in the front axle area that the actuator engages, and thought was fixed. But was inside the warm shop. They parked it outside overnight and you guessed it, same issue. Took it back inside and can't find what is problem. Said they checked the TCCM (?) but it was not that. I feel this is electrical issue as the trans/4wd works great in warm times......ANY IDEAS FOR ME TO RUN BY THE DEALER? They have had it for a week so far. I feel they are making honest effort but its a mystery...
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  #2  
Old 02-06-2010, 10:08 PM
the roadie's Avatar
the roadie the roadie is offline
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2004 GMC Envoy SLT "Roadiemobile"
Extreme Offroad Pewter 4.2L I6 4X4
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It should be obvious to a trained and experienced mechanic, but they need to drag their Tech II tool out to the truck while it's cold and misbehaving. If it isn't the TCCM (transfer case control module) which is behind the dash near the driver's left knee, then it's the wiring or the switch. The Tech II tool can command the TCCM to exercise the front axle actuator PLUS the encoder motor that changes the modes on the transfer case itself.

If the Service 4WD light never comes on, then that rules out a communication issue from the PCM to the TCCM.

Are you paying them to go through this guessing game, or do you have an extended warranty? They should have access to better tech support engineers at GM than we are at trailvoy, you'd think.
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  #3  
Old 02-07-2010, 02:20 PM
kip45223 kip45223 is offline
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Paid 500 bucks for initial repair, that didnt do it. They havent said anything yet. Gave me a loaner 03 TB til they figure it out. Never a service 4wd light
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  #4  
Old 02-08-2010, 09:27 PM
kip45223 kip45223 is offline
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2005 Chevy TrailBlazer LS
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The dealer finally listened a bit to me. They let it sit outside and checked the TB after sitting in cold, voila, encoder motor sensor bad. Works great now............. SO Far...... no extra charge for troubleshooting a whole week but still got 475 bucks but I got my car back.....I'll take it!
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  #5  
Old 02-22-2015, 03:41 PM
PackFan4 PackFan4 is offline
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2004 Chevy TrailBlazer LS EXT
Burgandy 4.2L I6 4X4
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Location: Minneapolis, mn
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Free fix

FREE FIX. Hi. I have the same issue with my 2004 Trailblazer. In the cold, sometimes the 4wd selector switch lights flash at start up, and after 10-15 seconds, they go off. After thinking about it, I wondered if the Encoder motor was having a syncing/positioning problem. The next time I started it up, when the selector lights began to flash, I quickly pushed the brake pedal and shifted the gear lever to Neutral. BINGO, it worked!!! The selector light locked solid and functioned normally. I live in a snowy climate, so yes, the transfer case is shifting into AWD and 4HI after doing this.
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  #6  
Old 03-03-2015, 12:59 PM
robcrum robcrum is offline
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2004 Isuzu Ascender
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thank you!

I had same problem with my 04 isuzu ascender( identical to 04 tb) I read your post about shifting into neuteral, and, like you explained, it resolved instantly! thank yiu so much for saving me what was sure to be big bucks at the stealership!!
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  #7  
Old 03-07-2015, 01:18 PM
PackFan4 PackFan4 is offline
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2004 Chevy TrailBlazer LS EXT
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Happy I could help robcrum.

Stealership, I love it!!!
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  #8  
Old 03-07-2015, 10:06 PM
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EnvoyBoy2004 EnvoyBoy2004 is online now
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2004 GMC Envoy SLT
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Not to burst anyone's bubble, but this may be a temporary solution. It sounds to me that something is binding either in the transfer case or the splined disconnect causing the encoder motor or the actuator not to complete its action. Selecting neutral eases some tension and allows the action to complete. Normally, going into or coming out of 4HI or A4WD can be done in gear and moving. Eventually this problem may become worse.
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  #9  
Old 03-08-2015, 07:12 PM
PackFan4 PackFan4 is offline
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2004 Chevy TrailBlazer LS EXT
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EnvoyBoy2004,

Thank you for your reply, but This problem occurs when the temp dips below 10-20 degrees F. Sometimes as little as a 5 to 10 degree dip will render the 4wd inoperable. Also, why would the gears bind with this temp change? Also, what is the tension difference from when the TB is in neutral compared to Park? I have an electronics background. When the temp goes down, resistance goes up. There is a reason the problem is resolved when the actuator motor sensor is changed (electronic). I understand and respect your concern. This is not a fix for all 4wd problems, but it seems to work in this situation. I will save the $500.
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  #10  
Old 03-09-2015, 04:42 PM
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EnvoyBoy2004 EnvoyBoy2004 is online now
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2004 GMC Envoy SLT
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I am talking about mechanical tension in the driveline.
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